Vir Biotechnology (VIR) 10-K 25 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Feb. 22, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Trading Symbol	VIR
Title of 12(b) Security	Common Stock, $0.0001 par value
Security Exchange Name	NASDAQ
Entity Registrant Name	Vir Biotechnology, Inc.
Entity Central Index Key	0001706431
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		127,836,816
Entity Public Float			$ 2.3
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Document Annual Report	true
Document Transition Report	false
Entity File Number	1-39083
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-2730369
Entity Address, Address Line One	499 Illinois Street, Suite 500
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94158
City Area Code	415
Local Phone Number	906-4324
ICFR Auditor Attestation Flag	true
Documents Incorporated by Reference	Portions of the definitive proxy statement, or the Proxy Statement, for the Registrant’s 2021 Annual Meeting of Stockholders are incorporated by reference into Part III of this Annual Report on Form 10-K. The Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the Registrant’s fiscal year ended December 31, 2020.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 436,575	$ 109,335
Short-term investments	300,286	274,101
Restricted cash and cash equivalents, current	7,993	6,181
Prepaid expenses and other current assets	27,511	13,378
Total current assets	772,365	402,995
Intangible assets, net	33,820	35,694
Goodwill	16,937	16,937
Property and equipment, net	17,946	16,308
Operating right-of-use assets	61,947
Restricted cash and cash equivalents, noncurrent	6,919	7,300
Long-term investments		24,290
Other assets	8,827	8,547
TOTAL ASSETS	918,761	512,071
CURRENT LIABILITIES:
Accounts payable	5,077	5,881
Accrued and other liabilities	76,936	26,495
Deferred revenue, current portion	6,451	6,181
Contingent consideration, current portion	10,600	8,200
Derivative liability		12,449
Total current liabilities	99,064	59,206
Deferred revenue, noncurrent	3,815	12,670
Operating lease liabilities, noncurrent	66,556
Contingent consideration, noncurrent	25,374	9,380
Deferred tax liability	3,253	3,305
Other long-term liabilities	3,847	3,568
TOTAL LIABILITIES	201,909	88,129
Commitments and contingencies (Note 9)
STOCKHOLDERS’ EQUITY:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized as of December 31, 2020 and 2019, respectively; no shares issued and outstanding as of December 31, 2020 and 2019
Common stock, $0.0001 par value; 300,000,000 shares authorized as of December 31, 2020 and 2019, respectively; 127,416,740 and 107,648,925 shares issued and outstanding as of December 31, 2020 and 2019, respectively	13	11
Additional paid-in capital	1,385,301	793,051
Accumulated other comprehensive loss	(1,278)	(601)
Accumulated deficit	(667,184)	(368,519)
TOTAL STOCKHOLDERS’ EQUITY	716,852	423,942
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 918,761	$ 512,071

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	127,416,740	107,648,925
Common stock, shares outstanding	127,416,740	107,648,925

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue:
Total revenue	$ 76,368	$ 8,091	$ 10,668
Operating expenses:
Research and development	302,411	148,472	100,229
General and administrative	70,937	37,598	29,131
Total operating expenses	373,348	186,070	129,360
Loss from operations	(296,980)	(177,979)	(118,692)
Other income (expense):
Interest income	2,836	8,511	2,540
Other expense, net	(4,467)	(5,061)	(212)
Total other income (expense)	(1,631)	3,450	2,328
Loss before (provision for) benefit from income taxes	(298,611)	(174,529)	(116,364)
(Provision for) benefit from income taxes	(54)	(154)	480
Net loss	$ (298,665)	$ (174,683)	$ (115,884)
Net loss per share, basic and diluted	$ (2.51)	$ (5.76)	$ (15.12)
Weighted-average shares outstanding, basic and diluted	119,159,424	30,349,920	7,666,463
Grant Revenue [Member]
Revenue:
Total revenue	$ 9,123	$ 7,380	$ 9,800
License
Revenue:
Total revenue	22,747
Contract Revenue [Member]
Revenue:
Total revenue	$ 44,498	$ 711	$ 868

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Net loss	$ (298,665)	$ (174,683)	$ (115,884)
Other comprehensive income (loss):
Unrealized gains (losses) on investments	(50)	149	(14)
Amortization of actuarial loss	23
Adjustment to projected benefit obligations, net of tax	(650)	(736)
Other comprehensive loss	(677)	(587)	(14)
Comprehensive loss	$ (299,342)	$ (175,270)	$ (115,898)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	IPO	Follow-on Offering	Convertible Preferred Stock	Series A-1 Convertible Preferred Stock	Series A-2 Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Common StockIPO	Common StockFollow-on Offering	Additional Paid-in Capital	Additional Paid-in CapitalIPO	Additional Paid-in CapitalFollow-on Offering	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance at Dec. 31, 2017	$ (68,916)							$ 1			$ 9,035				$ (77,952)
Beginning balance (in shares) at Dec. 31, 2017				65,944,430
Beginning balance at Dec. 31, 2017				$ 292,525
Beginning balance (in shares) at Dec. 31, 2017								6,210,325
Issuance of convertible preferred stock, net of issuance cost					$ 14,269	$ 2,343
Issuance of convertible preferred stock, net of issuance cost (in Shares)					3,222,220	743,870
Vesting of restricted common stock (in shares)								2,247,673
Exercise of stock options	584										584
Exercise of stock option (in shares)								400,801
Stock-based compensation	5,053										5,053
Other comprehensive loss	(14)													$ (14)
Net loss	(115,884)														(115,884)
Ending balance at Dec. 31, 2018	(179,177)							$ 1			14,672			(14)	(193,836)
Ending balance (in shares) at Dec. 31, 2018				69,910,520
Ending balance at Dec. 31, 2018				$ 309,137
Ending balance (in shares) at Dec. 31, 2018								8,858,799
Issuance of convertible preferred stock, net of issuance cost							$ 327,475
Issuance of convertible preferred stock, net of issuance cost (in Shares)							18,202,213
Conversion of convertible preferred stock into common stock	$ 636,612							$ 9			636,603
Conversion of convertible preferred stock into common (in shares)	(88,112,733)
Conversion of convertible preferred stock into common stock	$ (636,612)
Conversion of convertible preferred stock into common stock (in shares)								88,112,733
Issuance of common stock		$ 126,411							$ 1			$ 126,410
Issuance of common stock (in shares)									7,142,858
Reclassification of warrant liability to additional paid-in capital	3,073										3,073
Settlement of fractional shares from reverse stock split	(3)										(3)
Issuance of common stock in connection with a license agreement	617										617
Issuance of common stock in connection with a license agreement (in shares)								38,888
Repayment of promissory notes, net of unvested shares	1,355										1,355
Repayment of promissory notes, net of unvested shares (in shares)								1,390,925
Vesting of restricted common stock	476										476
Vesting of restricted common stock (in shares)								1,348,297
Exercise of stock options	1,129										1,129
Exercise of stock option (in shares)								756,425
Stock-based compensation	8,719										8,719
Other comprehensive loss	(587)													(587)
Net loss	(174,683)														(174,683)
Ending balance at Dec. 31, 2019	$ 423,942							$ 11			793,051			(601)	(368,519)
Ending balance (in shares) at Dec. 31, 2019	107,648,925							107,648,925
Reclassification of derivative liability to addition paid-in-capital	$ 29,245										29,245
Issuance of common stock in connection with the achievement of a milestone (in shares)								1,111,111
Issuance of common stock in connection with a collaboration agreement	206,699							$ 1			206,698
Issuance of common stock in connection with a collaboration agreement (in shares)								6,626,027
Issuance of common stock for cashless exercise of warrant (in shares)								211,774
Issuance of common stock			$ 323,214							$ 1			$ 323,213
Issuance of common stock (in shares)										8,214,285
Vesting of restricted common stock	1,435										1,435
Vesting of restricted common stock (in shares)								1,986,250
Exercise of stock options	4,059										4,059
Exercise of stock option (in shares)								1,618,368
Stock-based compensation	27,600										27,600
Other comprehensive loss	(677)													(677)
Net loss	(298,665)														(298,665)
Ending balance at Dec. 31, 2020	$ 716,852							$ 13			$ 1,385,301			$ (1,278)	$ (667,184)
Ending balance (in shares) at Dec. 31, 2020	127,416,740							127,416,740

Consolidated Statements of Co_2

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Initial public offering costs		$ 16,446
Common stock issuance cost	$ 21,786
Series A-1 Convertible Preferred Stock
Convertible preferred stock, net of issuance cost			$ 232
Series B Convertible Preferred Stock
Convertible preferred stock, net of issuance cost		$ 165

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (298,665)	$ (174,683)	$ (115,884)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	4,400	3,294	1,618
Amortization of intangible assets	1,042	1,223	1,138
Impairment of intangible assets	832
Amortization of premiums (accretion of discounts) on investments, net	1,548	(179)	(328)
Noncash lease expense	3,371
Change in estimated fair value of contingent consideration	38,394	8,330	250
Payment of contingent consideration in excess of acquisition date fair value	(15,752)
Initial fair value of derivative liability		13,599
Change in estimated fair value of derivative liability	16,796	(1,150)
Change in estimated fair value of convertible preferred stock warrant liability		2,049	95
Preferred stock issued in connection with asset acquisition			1,750
Common stock issued in connection with license agreement		617
Change in deferred income taxes	(52)		(480)
Stock-based compensation	27,600	8,719	5,053
Loss on write-off and disposal of property and equipment		345	198
Other	23
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(4,475)	(4,619)	(4,172)
Other assets	(1,100)	(1,881)	151
Accounts payable	(790)	964	1,471
Accrued liabilities and other long-term liabilities	46,614	10,211	7,171
Operating lease liabilities	(3,684)
Deferred revenue	(7,043)	3,529	7,873
Net cash used in operating activities	(190,941)	(129,632)	(94,096)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(6,549)	(8,940)	(8,192)
Purchases of investments	(403,841)	(643,898)	(123,105)
Maturities of investments	400,348	396,680	72,574
Proceeds from sale of property and equipment			25
Asset acquisitions			(1,743)
Proceeds from disposal of an asset held for sale	180
Net cash used in investing activities	(9,862)	(256,158)	(60,441)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	323,214	126,411
Proceeds from issuance of convertible preferred stock, net of issuance costs		317,335	14,254
Proceeds received from financing lease obligation		1,202
Payment of contingent consideration	(4,248)
Payment of principal on financing lease obligations	(250)	(95)
Proceeds from repayment of promissory notes		3,265
Proceeds from exercise of stock options	4,059	1,129	584
Cash paid in lieu of fractional shares related to reverse stock split		(3)
Advanced proceeds from convertible preferred stock financing			10,140
Net cash provided by financing activities	529,474	449,244	24,978
Net increase (decrease) in cash, cash equivalents and restricted cash and cash equivalents	328,671	63,454	(129,559)
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	122,816	59,362	188,921
Cash, cash equivalents and restricted cash and cash equivalents at end of period	451,487	122,816	59,362
NONCASH INVESTING AND FINANCING ACTIVITIES:
Property and equipment purchases included in accounts payable and accrued liabilities	382	892	1,996
Issuance of preferred stock in connection with asset acquisition			593
Conversion of preferred stock into common stock upon completion of initial public offering		636,612
Operating lease liabilities obtained in exchange of right-of-use asset	48,495
Advanced proceeds applied to convertible preferred stock issuance		10,140
Reclassification of derivative liability to additional paid-in capital	29,245
Reclassification of preferred stock warrant liability to additional paid-in capital		3,073
RECONCILIATION OF CASH, CASH EQUIVALENTS AND RESTRICTED CASH TO THE CONSOLIDATED BALANCE SHEETS:
Cash and cash equivalents	436,575	109,335	47,598
Restricted cash and cash equivalents, current	7,993	6,181	10,761
Restricted cash and cash equivalents, noncurrent	6,919	7,300	1,003
Cash, cash equivalents and restricted cash and cash equivalents at end of period	451,487	$ 122,816	$ 59,362
Collaboration Agreement
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	$ 206,699

Organization

Organization	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Organization	1. Vir Biotechnology, Inc. (“Vir” or the “Company”) is a clinical-stage immunology company focused on combining immunologic insights with cutting-edge technologies to treat and prevent serious infectious diseases. Its development pipeline consists of product candidates targeting the current coronavirus disease 2019 (“COVID-19”), hepatitis B virus (“HBV”), influenza A virus, and human immunodeficiency virus (“HIV”). Vir has assembled four technology platforms that are designed to stimulate and enhance the immune system by exploiting critical observations of natural immune processes. Reverse Stock Split On September 16, 2019, the Company’s board of directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a 1-for-4.5 reverse split (“Reverse Split”) of shares of the Company’s common and convertible preferred stock, which was effected on September 27, 2019. The par value per share and authorized shares of common stock and convertible preferred stock were not adjusted as a result of the Reverse Split. All of the share and per share information included in the accompanying consolidated financial statements has been adjusted to reflect the Reverse Split. Initial Public Offering On October 10, 2019, the Company completed its initial public offering (“IPO”) of its common stock. In connection with its IPO, the Company issued and sold 7,142,858 shares of its common stock at $20.00 per share. As a result of the IPO, the Company received $126.4 million in net proceeds, after deducting underwriting discounts, commissions and offering expenses. At the closing of the IPO, 88,112,733 shares of outstanding convertible preferred stock were automatically converted into 88,112,733 shares of common stock and a warrant to purchase 244,444 shares of convertible preferred stock was converted into a warrant to purchase 244,444 shares of common stock. Follow-On Offering On July 10, 2020, the Company issued and sold 8,214,285 shares of the Company’s common stock pursuant to a registration statement on Form S-1 (File No. 333-239689) and a registration statement on Form S-1 filed pursuant to Rule 462(b) under the Securities Act of 1933, as amended (the “Securities Act”) (File No. 333-239747) (collectively, the “Registration Statements”). The Registration Statements became effective on July 7, 2020. The price of the shares sold in the follow-on offering was $42.00 per share and the Company received total gross proceeds from the offering of approximately $345.0 million. After deducting underwriting discounts and commissions of $20.7 million and offering expenses of $1.1 million, the net proceeds were $323.2 million. Sales Agreement In November 2020, the Company entered into a sales agreement (the “Sales Agreement”) with Cowen and Company, LLC (“Cowen”), under which the Company may from time to time offer and sell shares of its common stock, par value $0.0001 per share, having an aggregate offering price of up to $300.0 million, through or to Cowen, acting as sales agent or principal. The shares will be offered and sold under the Company’s shelf registration statement on Form S-3 (the “S-3 Registration Statement”) and a related prospectus filed with the Securities and Exchange Commission on November 10, 2020. The Company will pay Cowen a commission of up to 3.0% of the aggregate gross proceeds from each sale of shares, reimburse legal fees and disbursements and provide Cowen with customary indemnification and contribution rights. As of December 31, 2020, no shares have been issued under the Sales Agreement. Need for Additional Capital The Company has incurred net losses since inception and expects such losses to continue over the next several years. At December 31, 2020, the Company had an accumulated deficit of $667.2 million. Management expects to incur additional losses in the future to conduct research and development and recognizes the need to raise additional capital to fully implement its business plan. The Company had, excluding restricted cash, $736.9 million of cash, cash equivalents, and short-term investments at December 31, 2020. Based on the Company’s business plans, management believes that its cash, cash equivalents, and short-term investments as of December 31, 20 20 will be sufficient to fund its operations for at least the next 12 months from the issuance date of these consolidated financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Basis of Presentation The Company’s consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and include all adjustments necessary for the fair presentation of the Company’s financial position for the periods presented. The consolidated financial statements include the accounts of Vir and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated upon consolidation. Foreign Currency The functional currency of the Company’s foreign subsidiaries is the U.S. dollar. Monetary assets and liabilities of foreign subsidiaries are translated into U.S. dollars at period-end exchange rates and non-monetary assets and liabilities are translated to U.S. dollars using historical exchange rates. Revenue and expenses are translated at average rates throughout the respective periods. Transaction gains and losses are included in other income (expense), net on the consolidated statements of operations and were immaterial for the years ended December 31, 2020, 2019 and 2018. Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expense during the reporting periods. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could materially differ from those estimates. Segments The Company has one operating segment. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for purposes of allocating resources. Concentration of Credit Risk, Credit Loss and Other Risks and Uncertainties With the global spread of the current COVID-19 pandemic, the Company has implemented a number of plans and policies designed to address and mitigate the impact of the COVID-19 pandemic on its business. The Company anticipates that the COVID-19 pandemic will have an impact on the clinical development timelines for some of its clinical programs. The extent to which the COVID-19 pandemic impacts the Company’s business, clinical development and regulatory efforts, corporate development objectives and the value of and market for its common stock, will depend on future developments that are highly uncertain and cannot be predicted with confidence at this time, such as the ultimate duration of the pandemic, travel restrictions, quarantines, social distancing and business closure requirements in the United States, Europe and other countries, and the effectiveness of actions taken globally to contain and treat the disease. In addition, the Company is subject to a number of other challenges and risks similar to other biopharmaceutical companies in the early stage, including, but not limited to, the need to obtain adequate additional funding, possible failure of preclinical testing or clinical trials, the need to obtain marketing approval for its product candidates, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of the Company’s products and protection of proprietary technology. If the Company does not successfully obtain regulatory approval, commercialize or partner any of its product candidates, it will be unable to generate revenue from product sales or achieve profitability. Also, to the extent the current COVID-19 pandemic adversely affects the Company’s business and results of operations, it may also have the effect of heightening many of the other risks and uncertainties discussed above. Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents and short and long-term investments. Cash and cash equivalents are deposited in checking and sweep accounts at a financial institution. Such deposits may, at times, exceed federally insured limits. The Company has not experienced any losses on its deposits of cash and cash equivalents. The Company’s investment policy limits investments to certain types of securities issued by the U.S. government, its agencies and institutions with investment-grade credit ratings and places restrictions on maturities and concentration by type and issuer. The Company is exposed to credit risk in the event of a default by the financial institutions holding its cash, cash equivalents and investments, and issuers of the investments to the extent recorded on the consolidated balance sheets. As of December 31, 2020, the Company has no off-balance sheet concentrations of credit risk. Effective January 1, 2020, the Company adopted Accounting Standards Update (ASU) 2016-13, Financial Instruments — Credit Losses, (Topic 326): Measurement of Credit Losses on Financial Instruments, which changed the impairment model for most financial assets and certain other instruments. For receivables, the Company uses a new forward-looking expected loss model that generally results in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, the losses are recognized as allowances rather than as reductions in the amortized cost of the securities. The Company’s expected loss allowance methodology for the receivables is developed using historical collection experience, current and future economic market conditions, a review of the current aging status and financial condition of the entities. Specific allowance amounts are established to record the appropriate allowance for customers that have a higher probability of default. Balances are written off when determined to be uncollectible. The Company’s expected loss allowance methodology for the debt securities is developed by reviewing the extent of the unrealized loss, the size, term, geographical location, and industry of the issuer, the issuers’ credit ratings and any changes in those ratings, as well as reviewing current and future economic market conditions and the issuers’ current status and financial condition. The Company considered the current and expected future economic and market conditions surrounding the COVID-19 pandemic and determined that the estimate of credit losses was not significantly impacted. The adoption of the guidance did not have a material impact on the consolidated financial statements and related disclosures and there was no allowance for losses on available-for-sale debt securities which were attributable to credit risk for the year ended December 31, 2020. Cash and Cash Equivalents The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash and cash equivalents. Cash equivalents, which consist of amounts invested in money market funds, are stated at fair value. Investments Investments include available-for-sale securities and are carried at estimated fair value. The Company’s valuations of marketable securities are generally derived from independent pricing services based on quoted prices in active markets for similar securities at period end. Generally, investments with original maturities beyond three months at the date of purchase and which mature at, or less than 12 months from, the consolidated balance sheet date are considered short-term investments, with all others considered to be long-term investments. Unrealized gains and losses deemed temporary in nature are reported as a component of accumulated comprehensive income (loss). The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in interest income on the consolidated statements of operations. The Company, through its investment in Brii Biosciences Limited, holds privately held equity securities in which the Company does not have a controlling interest or significant influence. The Company’s investment in Brii Biosciences Limited is recorded at cost and adjusted for impairments and observable price changes with the same or similar security from the same issuer. The valuation of the Company’s investment in Brii Biosciences Limited utilizes significant unobservable inputs or data in an inactive market and the valuation requires the Company’s judgment due to the absence of market prices and inherent lack of liquidity. Additionally, the determination of whether an orderly transaction is for the same or similar investment requires significant management judgment including the nature of the rights and obligations of its investments, the extent to which differences in those rights and obligations would affect the fair values of those investments, and the impact of any differences based on the stage of operational development of the investee. See Note 7—Collaboration and License Agreements for additional information on the Company’s investment in Brii Biosciences Limited. Restricted Cash and Cash Equivalents Restricted cash and cash equivalents represent money market funds to secure standby letters of credit and security deposits with financial institutions, both under office and laboratory space lease agreements. Additionally, funds received from certain grants are restricted as to their use and are therefore classified as restricted cash and cash equivalents. Property and Equipment, Net Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized over the lesser of their useful lives or the remaining life of the lease. When assets are retired or otherwise disposed of, the cost and related accumulated depreciation and amortization are removed from the balance sheet and the resulting gain or loss is reflected in operations in the period realized. Maintenance and repairs are charged to operations as incurred. The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparing the carrying amount to the future net undiscounted cash flows which the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the asset. No material impairment losses have been incurred to date. Acquired Intangible Assets The Company’s intangible assets were acquired via business combinations or asset acquisitions. Indefinite-lived intangible assets represent the estimated fair value assigned to in-process research and development (“IPR&D”) acquired in a business combination. The Company reviews indefinite-lived intangible assets for impairment at least annually or more frequently if events or changes in circumstances indicate that the carrying value of the assets might not be recoverable. If the carrying value of an indefinite-lived intangible asset exceeds its fair value, then it is written down to its adjusted fair value. As of December 31, 2020, there have been no such impairments. For IPR&D, if a product candidate derived from the indefinite-lived intangible asset is developed and commercialized, the useful life will be determined, and the carrying value will be amortized prospectively over that estimated useful life. Alternatively, if a product candidate is abandoned, the carrying value of the intangible asset will be charged to research and development expenses. IPR&D assets acquired as part of an asset acquisition are recorded at cost and expensed immediately if they have no alternative future uses. Finite-lived intangible assets acquired are initially recognized at their fair value at the acquisition date. Amortization is computed using the straight-line method over the estimated useful lives of the respective finite-lived intangible assets, generally seven to 15 years. Finite-lived intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Goodwill Goodwill represents the excess of the purchase price over the estimated fair value of the net tangible and intangible assets acquired in a business combination. The Company tests goodwill for impairment at least annually or more frequently if events or changes in circumstances indicate that this asset may be impaired. Revenue Recognition Grant Revenue Grants received, including cost reimbursement agreements, are assessed to determine if the agreement should be accounted for as an exchange transaction or a contribution. An agreement is accounted for as a contribution if the resource provider does not receive commensurate value in return for the assets transferred. Contributions are recognized as grant revenue when all donor-imposed conditions have been met. License and Cont . ract Revenue In accordance with Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“ASC 606”), the Company recognizes revenue when the Company’s customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods and services. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when or as the Company satisfies a performance obligation. For collaborative arrangements that fall within the scope of ASC 808, Collaborative Arrangements (“ASC 808”), the Company first determines which elements of the collaboration are deemed to be a performance obligation with a customer within the scope of ASC 606. For elements of collaboration arrangements that are accounted for pursuant to ASC 808 and are not subject to the guidance in ASC 606, the Company applies the revenue recognition model under ASC 606 or other guidance, as deemed appropriate. The Company has entered into a number of license and collaboration agreements that fall within the scope of ASC 606. The Company evaluates the promised goods or services in these agreements to determine which ones represent distinct performance obligations. These agreements may include the following types of promised goods or services: (i) grants of licenses, (ii) performance of research and development services, and (iii) participation on joint research and/or development committees. They also may include options to obtain licenses to the Company’s intellectual property. Prior to recognizing revenue, the Company makes estimates of the transaction price, including variable consideration that is subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. These estimates are re-assessed each reporting period as required. These agreements may include the following types of consideration: non-refundable upfront payments, reimbursement for research services, research, development or regulatory milestone payments, and royalty and commercial sales milestone payments. If there are multiple distinct performance obligations, the Company allocates the transaction price to each distinct performance obligation based on their estimated standalone selling prices. For performance obligations satisfied over time, the Company estimates the efforts needed to complete the performance obligation and recognizes revenue by measuring the progress towards complete satisfaction of the performance obligation using an input measure. For arrangements that include sales-based royalties, including commercial milestone payments based on pre-specified level of sales, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Achievement of these royalties and commercial milestones may solely depend upon performance of the licensee. Research and Development Expenses To date, research and development expenses have related primarily to discovery efforts and preclinical and clinical development of product candidates. Research and development expenses are recognized as incurred and payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods or services are received. Research and development expenses include expenses related to license and collaboration agreements; contingent consideration from business acquisitions; personnel-related expenses, including salaries, benefits, and stock-based compensation for personnel contributing to research and development activities; expenses incurred under agreements with third-party contract manufacturing organizations, contract research organizations, and consultants; clinical costs, including laboratory supplies and costs related to compliance with regulatory requirements; and other allocated expenses, including expenses for rent, facilities maintenance, and depreciation and amortization. The Company has and may continue to acquire the rights to develop and commercialize new product candidates from third parties. Upfront payments and research and development milestone payments made in connection with acquired license or product rights are expensed as incurred, provided that they do not relate to a regulatory approval milestone or assets acquired in a business combination. The Company’s expense accruals for clinical trials and manufacturing are based on estimates of contracted services provided by third-party vendors not yet billed. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of its outstanding obligations to those third parties as of the period end. The accrual estimates are based on a number of factors, including the Company’s knowledge of the research and development programs and clinical manufacturing activities, the status of the programs and activities, invoicing to date, and the provisions in the contracts. The Company obtains information regarding unbilled services directly from these service providers and performs procedures to support its estimates based on its internal understanding of the services provided to date. However, the Company may also be required to estimate these services based on information available to its internal clinical and manufacturing administrative staff if such information is not able to be obtained timely from its service providers. Stock-based Compensation The Company recognizes stock-based compensation to employees and non-employees over the requisite service period based on the estimated grant-date fair value of the awards. The Company calculates the fair value of stock options using the Black-Scholes valuation model. Stock-based compensation is recognized using the straight-line method for awards that vest only upon the employee’s or non-employee’s continued service to the Company. Forfeitures are recognized as they occur. Acquisitions Business combinations are accounted for using the acquisition method of accounting. Under the acquisition method, assets acquired, including IPR&D projects, and liabilities assumed are recorded at their respective fair values as of the acquisition date. Any excess fair value of consideration transferred over the fair value of the net assets acquired is recorded as goodwill. Contingent consideration obligations incurred in connection with the business combination are recorded at their fair values on the acquisition date and are remeasured each subsequent reporting period until the related contingencies are resolved and are classified as contingent consideration on the consolidated balance sheets. The changes in fair values of contingent consideration related to the achievement of various milestones related to product candidates are recorded within research and development expense. When the Company determines that entities acquired do not meet the definition of a business, the transaction is accounted for as an acquisition of assets. Therefore, the consideration paid to acquire IPR&D is expensed, and no goodwill is recorded. Any contingent consideration is generally recognized only when it becomes payable or is paid. Embedded Derivatives The Company evaluates its acquisitions, collaborative arrangements and other business development transactions to determine if embedded components of these contracts meet the definition of a derivative under ASC 815, Derivatives and Hedging. In general, embedded derivatives are required to be bifurcated from the host instrument if (i) the embedded feature is not clearly and closely related to the host contract and (ii) the embedded feature, if considered a freestanding instrument, meets the definition of a derivative. Embedded derivatives are reported on the consolidated balance sheets at their estimated fair values. Contingent consideration related to asset acquisitions that meet the definition of an embedded derivative is classified as contingent consideration on the consolidated balance sheets. Any change in estimated fair values, as determined at each measurement period, are recorded in the consolidated statements of operations based on the nature of the related contingencies. Leases In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, Leases (“ASC 842”). ASC 842 requires lessees to recognize all leases, including operating leases, on the balance sheet as a right-of-use (“ROU”) asset and a lease liability, unless the lease is a short-term lease, defined as having a term of 12 months or less. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements. In issuing ASU 2018-11, the FASB decided to provide another transition method by allowing entities to initially apply the new leases standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. ASC 842 is effective for the Company for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020, with early adoption permitted. The Company early adopted the standard on January 1, 2020 using the optional modified retrospective transition method by recognizing a cumulative effect adjustment to the opening balance of accumulated deficit as of that date. Results for the year ended December 31 , 2020 are presented under ASC 842. The prior period amounts were not adjusted and continue to be reported in accordance with previous lease guidance, ASC 840, Leases. The Company elected the package of practical expedients allowed under ASC 842, which permits the Company to account for its existing operating leases as operating leases under the new guidance, without reassessing the Company’s prior conclusions about lease identification, lease classification and initial direct cost. Adoption of ASC 842 resulted in the recognition of operating lease ROU assets and operating lease liabilities of $16.8 million and $17.5 million, respectively, on the Company’s consolidated balance sheet as of January 1, 2020. The difference between the ROU assets and lease liabilities is attributed to the elimination of deferred rent. The adoption of the new standard did not have an impact on the Company's beginning accumulated deficit or statement of operations. The Company determines if an arrangement is or contains a lease at inception by assessing whether the arrangement contains an identified asset and whether it has the right to control the identified asset. ROU assets represent the Company's right to use an underlying asset for the lease term and lease liabilities represent the Company's obligation to make lease payments arising from the lease. Lease liabilities are recognized at the lease commencement date based on the present value of future lease payments over the lease term. ROU assets are based on the measurement of the lease liability and also include any lease payments made prior to or on lease commencement and exclude lease incentives and initial direct costs incurred, as applicable. On the lease commencement date, the Company estimates and includes in its lease payments any lease incentive amounts based on future events when (1) the events are within the Company’s control and (2) the event triggering the right to receive the incentive is deemed reasonably certain to occur. If the lease incentive received is greater or less than the amount recognized at lease commencement, the Company recognizes the difference as an adjustment to right-of-use asset and/or lease liability, as applicable. As the implicit rate in the Company's leases is generally unknown, the Company uses an incremental borrowing rate estimated based on the information available at the lease commencement date in determining the present value of future lease payments. When calculating its estimated incremental borrowing rates, the Company considers its credit risk, the lease term, the total lease payments and the impact of collateral, as necessary. The lease terms may include options to extend or terminate the lease when the Company is reasonably certain it will exercise such options. ROU assets and lease liabilities are remeasured upon certain modifications to leases using the present value of remaining lease payments and estimated incremental borrowing rate upon lease modification. Rent expense for the Company's operating leases is recognized on a straight-line basis within operating expenses over the reasonably assured lease term. The Company elected to not separate lease and non-lease components for any leases within its existing classes of assets and, as a result, accounts for the lease and non-lease components as a single lease component. The Company has also elected to not apply the recognition requirement to any leases within its existing classes of assets with a term of 12 months or less. Pension Benefits Accounting for the defined pension benefit plan for the Company’s Swiss subsidiary requires actuarial valuations based on significant assumptions for discount rates and expected long-term rates of return on plan assets. These and other assumptions such as salary growth, retirement, and mortality rates are evaluated and selected based on expectations or actual experience during each remeasurement date. Actual results in any given year may differ from those estimated because of economic and other factors. The Company recognizes a liability for the underfunded status of its defined benefit pension plan as a component of other long-term liabilities. Actuarial gains or losses and prior service costs or credits are deferred in accumulated other comprehensive income (loss) and amortized over the remaining service attribution periods of the employees under the corridor method. Income Taxes The Company uses the asset and liability method of accounting for income taxes. Current income tax expense or benefit represents the amount of income taxes expected to be payable or refundable for the current year. Deferred income tax assets and liabilities are determined based on differences between the financial statement reporting and tax bases of assets and liabilities and net operating losses and credit carryforwards and are measured using the enacted tax rates and laws that will be in effect when such items are expected to reverse. Deferred income tax assets are reduced, as necessary, by a valuation allowance when management determines it is more likely than not that some or all of the tax benefits will not be realized. The Company’s tax positions are subject to income tax audits. The Company recognizes the tax benefit of an uncertain tax position only if it is more likely than not that the position is sustainable upon examination by the taxing authority, based on the technical merits. The tax benefit recognized is measured as the largest amount of benefit which is more likely than not to be realized upon settlement with the taxing authority. The Company evaluates uncertain tax positions on a regular basis. The evaluations are based on several factors, including changes in facts and circumstances, changes in tax law, correspondence with tax authorities during the course of the audit, and effective settlement of audit issues. The provision for income taxes includes the effects of any accruals that the Company believes are appropriate, as well as any related net interest and penalties. Net Loss Per Share Basic net loss per common share is computed by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration of common stock equivalents. Diluted net loss per common share is computed by dividing the net loss by the sum of the weighted average number of common shares outstanding during the period plus any potential dilutive effects of common stock equivalents outstanding during the period calculated in accordance with the treasury stock method. Diluted net loss per share is the same as basic net loss per share since the effect of potentially dilutive securities is anti-dilutive. Recently Adopted Accounting Pronouncements In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other: Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), which simplifies the current requirements for testing goodwill for impairment by eliminating the second step of the two-step impairment test to measure the amount of an impairment loss. ASU 2017-04 is effective for the Company’s interim and annual reporting periods beginning after December 31, 2021. The Company early adopted ASU 2017-04 on January 1, 2020 and the adoption had no impact on its consolidated financial statements. In August 2018, the FASB issued ASU 2018‑13, Fair Value Measurement (Topic 820) (“ASU 2018-13”), which modifies, removes and adds certain disclosure requirements on fair value measurements. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The Company adopted ASU 2018-13 on January 1, 2020 and the adoption resulted in additional disclosures related to the Company’s Level 3 financial instruments. See Note 3—Fair Value Measurements. In August 2018, the FASB issued ASU No. 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans (“ASU 2018-14”), which removes certain disclosures and added additional disclosures around weighted-average interest crediting rates for cash balance plans and explanation for significant gains and losses related to change in the benefit obligation for the period. The ASU will be effective for fiscal years ending after December 15, 2020 with a retrospective application for all periods presented. The Company adopted ASU 2018-14 at December 31, 2020 and the adoption had no material impact on its notes to consolidated financial statements. In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606 (“ASU 2018-18”). The amended guidance precludes presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. The Company determines the fair value of financial and non-financial assets and liabilities using the fair value hierarchy, which establishes three levels of inputs that may be used to measure fair value, as follows: • Level 1: Inputs which include quoted prices in active markets for identical assets and liabilities. • Level 2: Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. • Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The carrying amounts of the Company’s financial instruments, including accounts payable and accrued liabilities approximate fair value due to their relatively short maturities. The following tables summarize the Company’s Level 1 and Level 2 financial assets measured at fair value on a recurring basis by level within the fair value hierarchy: December 31, 2020 Valuation Hierarchy Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value (in thousands) Assets: Money market funds (1) Level 1 $ 421,835 $ — $ — $ 421,835 U.S. government treasuries Level 2 300,201 91 (6 ) 300,286 Total financial assets $ 722,036 $ 91 $ (6 ) $ 722,121 (1) Includes $14.9 million of restricted cash equivalents. December 31, 2019 Valuation Hierarchy Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value (in thousands) Assets: Money market funds (1) Level 1 $ 106,127 $ — $ — $ 106,127 U.S. government treasuries (2) Level 2 298,256 140 (5 ) 298,391 Bank time deposits Level 2 2,500 — — 2,500 Total financial assets $ 406,883 $ 140 $ (5 ) $ 407,018 (1) Includes $13.5 million of restricted cash equivalents. (2) Includes $24.3 million classified as long-term investments As of December 31, 2020 and 2019, there were no investments that have been in a continuous unrealized loss position for longer than 12 months. Total net unrealized gains of $0.1 million and $0.1 million were recorded in accumulated other comprehensive income (loss) at December 31, 2020 and 2019, respectively. As of December 31, 2020, no securities have contractual maturities of longer than one year. Level 3 liabilities consist of contingent consideration and derivative liability as of December 31, 2019. As of December 31, 2020, Level 3 liabilities consist of contingent consideration. Contingent Consideration Contingent consideration includes potential milestone payments in connection with the acquisitions of Humabs Biomed SA (“Humabs”) and TomegaVax, Inc. (“TomegaVax”). See further discussion in Note 4 — The estimated fair value of the contingent consideration related to the Humabs acquisition was determined by calculating the probability-weighted clinical, regulatory, and commercial milestone payments based on the assessment of the likelihood and estimated timing that certain milestones would be achieved. During the year ended December 31, 2020, the Company achieved two of the specified clinical milestones. As such, the Company paid a total of $20.0 million related to these milestones in 2020. As of December 31, 2020, the Company calculated the estimated fair value of the remaining clinical and regulatory milestones using the following significant unobservable inputs: Unobservable input Value or Range (Weighted-Average) 1 Discount rates 7% - 9% (8%) Probability of achievement 14% - 32% (27%) (1) Unobservable inputs were weighted based on the relative fair value of the underlying milestones. For the commercial milestones, the Company used a Monte Carlo simulation because of the availability of a discrete revenue forecast and the increased likelihood that the clinical trials would commence. As of December 31, 2020, the Monte Carlo simulation assumed a commercial product launch and associated discrete revenue forecast, as well as the following significant unobservable inputs: Unobservable input Value or Range (Weighted-Average) 1 Volatility 60% Discount rate 11% Probability of achievement 14% - 32% (28%) (1) Unobservable inputs were weighted based on the relative fair value of the commercial milestone payments. The discount rate captures the credit risk associated with the payment of the contingent consideration when earned and due. As of December 31, 2020 and December 31, 2019, the estimated fair value of the contingent consideration related to the Humabs acquisition was $29.2 million and $14.9 million, respectively, with changes in the estimated fair value recorded in research and development expense in the consolidated statements of operations. The estimated fair value of the contingent consideration related to the TomegaVax acquisition was determined by using a Monte Carlo simulation model which included estimates of both the probability and timing to achieve the required per share price of the Company’s common stock and incorporates assumptions as to expected volatility and discount rate. The discount rate captures the credit risk associated with the payment of the contingent consideration when earned and due. Although the TomegaVax acquisition was accounted for as an asset acquisition, such contingent consideration met the definition of an embedded derivative financial instrument. As of December 31, 2020, the fair value of the contingent consideration was estimated using the following significant unobservable inputs: Unobservable input Range (Weighted-Average) 1 Volatility 85% Discount rates 0% - 0.1% (0.1%) (1) Unobservable inputs were weighted based on the relative fair value of the underlying milestones. As of December 31, 2020 and December 31, 2019, the estimated fair value of the contingent consideration related to the TomegaVax acquisition was $6.8 million and $2.7 million, respectively, with changes in the estimated fair value recorded in other income (expense), net in the consolidated statements of operations. The estimated fair value of the contingent consideration related to the Humabs and TomegaVax acquisitions involves significant estimates and assumptions which give rise to measurement uncertainty. Derivative Liability The derivative liability relates to the Milestone Shares (as defined in Note 7) in connection with the collaboration and license agreement (the “Alnylam Agreement”) with Alnylam Pharmaceuticals, Inc. (“Alnylam”). See Note 7—Collaboration and License Agreements. The estimated fair value of the derivative liability was calculated based on the estimated probabilities of the likelihood and timing to achieve the development milestone, a discount for lack of marketability, and the fair value of the Milestone Shares using the Company’s closing stock price as of December 31, 2019 and March 10, 2020, the date the Company achieved the development milestone. As of December 31, 2019, the estimated fair value of the derivative liability was $12.4 million. On March 10, 2020, the Company remeasured and reclassified the derivative liability of $29.2 million to additional paid-in capital upon achievement of the development milestone. The following table sets forth the changes in the estimated fair value of the Company’s Level 3 financial liabilities (in thousands): Contingent Consideration Derivative Liability Total Balance at December 31, 2019 $ 17,580 $ 12,449 $ 30,029 Changes in fair value 38,394 16,796 55,190 Payment of contingent consideration related to Humabs acquisition (20,000 ) — (20,000 ) Reclassification of derivative liability to additional paid-in capital upon achievement of development milestone — (29,245 ) (29,245 ) Balance at December 31, 2020 $ 35,974 $ — $ 35,974

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Acquisitions	4. Acquisition of TomegaVax In September 2016, the Company entered into an agreement and plan of merger (“TomegaVax Merger Agreement”) to acquire all of the equity interests of TomegaVax. The primary asset purchased in the acquisition was an in-process cytomegalovirus (“CMV”) vector-based vaccine platform for use in HBV, HIV, and TB. The acquisition was accounted for as an asset purchase and the Company recorded the cash purchase price of $5.2 million in research and development expenses in 2016. The Company incurred transaction costs of $0.5 million. In connection with the entry into the TomegaVax Merger Agreement, the Company also entered into a letter agreement with TomegaVax (the “TomegaVax Letter Agreement”), which provides for certain payments to TomegaVax’s former stockholders before September 2024, in each case so long as the Company is continuing to pursue the development of the TomegaVax technology. Under the terms of the TomegaVax Letter Agreement, the Company will be required to pay to the former stockholders of TomegaVax milestone payments of up to an aggregate of $30.0 million if the per-share price of the Company’s publicly traded common stock, or implied price per-share of the Company’s Series A-1 convertible preferred stock (or common stock upon conversion) upon a certain asset sale, merger or stock sale, is at least $45 (as adjusted in the case of any stock dividend, stock split or other similar recapitalization), with the amount of such payments determined by the share price and the stage of the Company’s clinical development at the time of the relevant event triggering the payment. The share price of the Company’s publicly traded common stock will be determined using the average of the daily volume-weighted average trading price of the Company’s common stock for each trading day during a consecutive 90-day period. The foregoing payments are payable (i) during any date after the completion of an initial public offering by the Company or any successor or affiliate controlling the TomegaVax technology, provided that no payment will be due before the first anniversary of the initial public offering, (ii) upon the sale of all assets related to the TomegaVax technology or (iii) upon a merger or stock sale of the Company or any successor or affiliate controlling the TomegaVax technology, in each case subject to certain conditions with respect to the timing of the payments. The payments under the TomegaVax Letter Agreement can be made in cash or shares of the Company’s common stock, at the discretion of the Company’s board of directors. The Company determined that the future milestone payments contain net settlement provisions and therefore, they were required to be accounted for as embedded derivatives under the relevant accounting guidance. As of December 31, 2020, the fair value of the embedded derivative was $6.8 million and is included in the contingent consideration liability on the consolidated balance sheet. In February 2021, the Company achieved the specified share price resulting in a $10.0 million payable to TomegaVax’s former stockholders within 90 business days. Acquisition of Humabs In August 2017, the Company acquired all of the outstanding equity of Humabs, a private Swiss company which discovers and develops monoclonal antibodies (“mAbs”) derived from individuals whose immune systems have successfully responded to major diseases. The Company acquired all of Humabs’ rights, title and interest in and to substantially all of the assets of Humabs except for rights under certain license agreements with third-parties. The Company is obligated to pass-through to the former Humabs shareholders any amounts received by Humabs under such license agreements, net of any program expenses. The transaction was accounted for as an acquisition of a business. The consideration paid consisted of $30.0 million in cash and 1,666,656 shares of common stock, valued at $2.5 million as of the date of the transaction, to former Humabs shareholders. In addition to the cash payment and issuance of common stock to the former Humabs shareholders at the acquisition date, the Company also agreed to pay additional amounts in cash upon the achievement of specified milestone events: (i) up to $135.0 million upon the achievement of clinical, regulatory and commercial milestones for an HBV product; and (ii) up to $105.0 million upon the achievement of clinical, regulatory and commercial milestones for another product, which the Company elected as a severe acute respiratory syndrome coronavirus 2 (“SARS-CoV-2”) product. In May 2020, the Company achieved one of the specified clinical milestones for the HBV product. As such, the Company paid $10.0 million related to this milestone event in June 2020. In October 2020, the Company achieved another specified clinical milestone for the SARS-CoV-2 product and paid $10.0 million related to this milestone event. The acquired developed technologies that have associated patents issued are classified as finite-lived intangible assets and are amortized on a straight-lined basis over their estimated remaining useful lives, generally between seven to 12 years. The Company also acquired indefinite-lived intangible assets consisting of IPR&D. These assets will not be amortized until regulatory approval is obtained in a major market. At that time, the Company will determine the useful life of the asset and begin amortization. If the associated research and development effort is abandoned or otherwise impaired, the related IPR&D assets will be written-off and an impairment charge recorded. As of December 31, 2020, there have been no such impairments related to the IPR&D assets. The estimated fair value of the intangible assets was determined using the replacement cost method. The excess of the purchase price over the estimated fair value of the net assets acquired was recorded as goodwill. None of the goodwill is expected to be deductible for income tax purposes. Acquisition of Agenovir In January 2018, the Company entered into an agreement and plan of merger (the “Agenovir Merger Agreement”) with Agenovir Corporation (“Agenovir”), under which the Company purchased all equity interests of Agenovir. The primary assets purchased in the acquisition were IPR&D programs in human papillomavirus (“HPV”) and HBV using CRISPR/Cas9. The Company concluded that the assets acquired and liabilities assumed did not meet the definition of a business as a limited number of inputs were acquired but no substantive processes were acquired. As such, the acquisition was accounted for as an asset purchase. As purchase consideration, the Company paid cash of $11.5 million, issued an aggregate of 555,537 shares of Series A-2 convertible preferred stock valued at $1.8 million on the transaction date, assumed certain liabilities of $1.3 million, and incurred transaction costs of $0.7 million. The Company allocated the purchase price of $15.3 million between property and equipment of $0.8 million and in-process research and development of $14.5 million, based on the relative fair values of the assets acquired, which was expensed as research and development expenses in the accompanying consolidated statement of operations for the year ended December 31, 2018. During a specified period following the closing of the Agenovir acquisition, the Company will be required to pay Agenovir’s former stockholders additional consideration up to $135.0 million in the aggregate for the achievement of specified development, regulatory and commercial milestones for the first HBV product. None of the milestones have been achieved as of December 31, 2020, therefore no amounts were recognized relating to the contingent consideration.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	5. Goodwill Goodwill of $16.9 million represents the excess of the purchase price over the estimated fair value of the net assets acquired from Humabs. The Company tests goodwill for impairment on an annual basis or sooner, if deemed necessary. There was no impairment for the year ended December 31, 2020. Intangible Assets The following table summarizes the carrying amount of the Company’s finite-lived intangible assets (in thousands): December 31, Weighted- Average Remaining Useful 2020 2019 Life (Years) Developed technology $ 7,000 $ 7,000 6.6 Contract-based intangible asset 502 — 14.9 Finite-lived intangible assets, gross 7,502 7,000 Less accumulated amortization (3,581 ) (2,539 ) Less impairment of intangible assets (832 ) — Finite-lived intangible assets, net $ 3,089 $ 4,461 Finite-lived intangible assets are carried at cost less accumulated amortization. The contract-based intangible asset resulted from the product approval of a sublicensed intellectual property right. The intellectual property right was previously accounted for as IPR&D. Amortization expense related to finite-lived intangible assets, included in research and development expenses on the consolidated statements of operations, totaled $1.0 million, $1.2 million and $1.1 million for the years ended December 31, 2020, 2019 and 2018, respectively. Management reviews finite-lived intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable, like that of property and equipment. During the third quarter of 2020, as a result of the availability of other research and analytics platforms, the Company abandoned certain of its acquired developed technologies and concluded that the full remaining book values of the assets were impaired. Therefore, $0.8 million was written off as an impairment charge which was classified as research and development expenses. Based on the finite-lived intangible assets recorded as of December 31, 2020, the estimated future amortization expense for the next five years is as follows (in thousands): Year Ending December 31: 2021 $ 532 2022 532 2023 532 2024 260 2025 213 Total $ 2,069 Indefinite-Lived Intangible Assets As of December 31, 2020 and 2019, the Company had indefinite-lived intangible assets of $30.7 million and $31.2 million, respectively, related to the purchased IPR&D from the Humabs acquisition. In December 2020, $0.5 million was reclassed as a finite-lived intangible asset due to the product approval of a sublicensed intellectual property right. No impairment losses have been recorded for the years ended December 31, 2020 and 2019.

Grant Agreements

Grant Agreements	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Grant Agreements	6. Bill & Melinda Gates Foundation Grants Campylo/EPEC/EAEC Grant As part of the Company’s acquisition of Humabs in August 2017, the Company acquired a grant agreement with the Bill & Melinda Gates Foundation under which it was awarded a grant totaling up to $4.7 million (the “2017 Grant”). The 2017 Grant supported the Company’s discovery, characterization and selection of human monoclonal antibodies with pre-clinical efficacy against three enteric pathogens responsible for life-threatening diarrhea in neonates. The 2017 Grant expired on May 31, 2019. Payments received in advance that were related to future research activities were deferred and recognized as revenue when the donor-imposed conditions were met, which was as the research and development activities were performed. The Company recognized grant revenue of zero, $0.9 million and $2.0 million for the years ended December 31, 2020, 2019 and 2018, respectively. Human Immunodeficiency Virus (“HIV”) Grant On January 26, 2018, the Company entered into a grant agreement with the Bill & Melinda Gates Foundation under which it was awarded a grant totaling up to $12.2 million for its HIV program (the “HIV Grant”). In February 2020, the parties amended the HIV Grant under which the Company was awarded a supplemental grant of $8.6 million. Under the amendment, the HIV Grant will remain in effect until December 31, 2021, unless earlier terminated by the Bill & Melinda Gates Foundation for the Company’s breach, failure to progress the funded project, in the event of the Company’s change of control, change in the Company’s tax status, or significant changes in the Company’s leadership that the Bill & Melinda Gates Foundation reasonably believes may threaten the success of the project. In December 2020, the Company achieved a specified milestone under the HIV Grant which triggered a $1.9 million payment due to the Company from the Bill & Melinda Gates Foundation. As of December 31, 2020, the Company recorded a receivable, which is included within prepaid expenses and other current assets, and current portion of deferred revenue for the $1.9 million, which was subsequently received in January 2021. Payments received in advance that are related to future research activities are deferred and recognized as revenue when the donor-imposed conditions are met, which is as the research and development activities are performed. The Company recognized grant revenue of $6.4 million, $3.7 million and $4.4 million for the years ended December 31, 2020, 2019 and 2018, respectively. Tuberculosis (“TB”) Grant On March 16, 2018, the Company entered into a grant agreement with the Bill & Melinda Gates Foundation under which it was awarded a grant totaling up to $14.9 million for its TB program (the “TB Grant”). The parties amended the agreement in May 2020 under which the grant term was extended to February 28, 2021, unless earlier terminated by the Bill & Melinda Gates Foundation for the Company’s breach, failure to progress the funded project, in the event of the Company’s change of control, change in the Company’s tax status, or significant changes in the Company’s leadership that the Bill & Melinda Gates Foundation reasonably believes may threaten the success of the project. The Company estimates that $3.5 million of the funds received in advance and previously recorded as deferred revenue would not be earned by February 2021 and is therefore included within accrued and other liabilities as of December 31, 2020. Payments received in advance that are related to future research activities are deferred and recognized as revenue when the donor-imposed conditions are met, which is as the research and development activities are performed. The Company recognized grant revenue of $2.2 million, $1.9 million and $2.3 million for the years ended December 31, 2020, 2019 and 2018, respectively. National Institutes of Health As part of the Company’s acquisition of TomegaVax in September 2016, the Company acquired grant agreements related to TomegaVax’s research effort in infectious diseases and cancer that entitled them to several awards under the Small Business Innovation Research Program from the National Institutes of Health (“NIH”). Through December 31, 2020, the Company has acquired or been awarded grants from NIH totaling $5.1 million. These grants are cost plus fixed fee agreements in which the Company is reimbursed for its direct and indirect costs. Only costs that are allowable under certain government regulations and NIH’s supplemental policy and procedure manual may be claimed for reimbursement, subject to government audit. The Company recognized grant revenue of $0.6 million, $0.9 million and $1.1 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Collaboration and License Agree

Collaboration and License Agreements	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration and License Agreements	7. Collaboration and License Agreements GSK On June 9, 2020, the Company, Glaxo Wellcome UK Limited and Beecham S.A. (referred to individually and t For four years following the Effective Date, the parties will conduct certain research and development activities under mutually agreed development plans and associated budgets for each of the three programs, and under the oversight of a joint steering committee (“JSC”). The Company will be primarily responsible for the development and clinical manufacturing activities for the Antibody Program, and for conducting the initial development activities directed to a vaccine in the Vaccine Program. GSK will be primarily responsible for the commercialization activities for the Antibody Program (except in connection with sales of antibody products licensed to WuXi Biologics (Hong Kong) Limited in greater China), the later-stage development, manufacturing and commercialization activities for the Vaccine Program and the development, manufacturing and commercialization activities for the Functional Genomics Program. Subject to an opt-out mechanism, the parties will share all development costs, manufacturing costs and costs and expenses for the commercialization of the collaboration products, with the Company bearing 72.5% of such costs for the antibody products, 27.5% of such costs for the vaccine products, and equal sharing of such costs for the functional genomics products. On a collaboration product-by-collaboration product basis, each party will have the one-time right, at specified points in development, to opt-out of its co-funding obligations, and the other party may, at its election, either pursue such program unilaterally, or also cease research and development activities and funding of such collaboration product. If the opt-out provisions are not exercised by either party subject to the terms of the GSK Agreement, the parties would share all profits and losses arising from any collaboration product in the same ratios in which the parties bore development costs for such collaboration program. For each collaboration product as to which a party exercises its opt-out right, the commercializing party will pay to the opt-out party royalties on net sales of the applicable collaboration product at rates based on factors such as the stage of development of such collaboration product at the time the opt-out party exercises such right, and whether the opt-out party is the lead party, or a portion of the sublicense revenue if the commercializing party chooses to sublicense or otherwise divest rights to such collaboration product. On an antibody product-by-antibody product basis, the Company has a co-promotion right for such antibody product in the United States, under which the Company will have the right to perform up to 20 % of details in connection with such antibody product. The GSK Agreement will remain in effect with respect to each collaboration program for as long as there is a collaboration product being developed or commercialized by the lead party, or the non-opt-out party, in such program. Either party has the right to terminate the GSK Agreement in the case of the insolvency of the other party, an uncured material breach of the other party with respect to a collaboration program or collaboration product, or as mutually agreed by the parties. The GSK Agreement superseded and replaced the Preliminary Agreement between the parties. The Company considered the ASC 606 criteria for combining contracts and determined that the GSK Agreement and 2020 Stock Purchase Agreement should be combined into a single contract because they were negotiated and entered into in contemplation of one another. The fair market value of the common stock issued to GGL was $206.7 million, based on the closing stock price of $36.70 on the date of execution of the Preliminary Agreement and 2020 Stock Purchase Agreement and taking into account a discount for the lack of marketability due to the restrictions in place on the underlying shares, resulting in a $43.3 million premium received by the Company. The Company concluded that the GSK Agreement contained four units of account: (i) the license granted to GSK under the Antibody Program (the “Antibody License”); (ii) the research and development activities (including clinical manufacturing) under the Antibody Program; (iii) the research and development activities under the Vaccine Program; and (iv) the research and development activities under the Functional Genomics Program. The Company considered the guidance in ASC 606 to determine which of these elements of the GSK Agreement are performance obligations with a customer. The Company determined that the Antibody License is within the scope of ASC 606 and accordingly, accounted for the Antibody License as a distinct performance obligation under ASC 606. The Antibody License is a functional intellectual property and is distinct from the associated research and development activities to be performed under the program due to its significant standalone functionality. All other elements of the GSK Agreement including the research and development activities and participation in the JSC and subcommittees for each collaboration program were not determined to be distinct performance obligations with a customer. The transaction price for the Antibody License at inception was determined to be $43.3 million, representing the premium on the sale of common stock to GSK. The Company determined that GSK can benefit from the Antibody License at the time of grant and therefore, the related performance obligation is satisfied at a point in time. As such, the Company recognized the $43.3 million as contract revenue during the second quarter of 2020. Additionally, the Company is entitled to consideration from GSK related to profit and loss sharing arrangements (including royalties) contingent upon future sales of collaboration products under the Antibody Program. Under ASC 606, the Company will recognize the revenue when the related sales occur as these amounts have been determined to relate predominantly to the Antibody License granted to GSK. The Company will re-evaluate the transaction price in each reporting period. The remaining units of account of the GSK Agreement were determined to be within the scope of ASC 808 as the Company and GSK are both active participants in the development, manufacturing and commercialization activities and are exposed to significant risks and rewards that are dependent on the commercial success of the activities of the arrangement. Furthermore, the Company and GSK participate in the commercial profit and loss sharing arrangement for each program commensurate with each party’s cost-sharing responsibilities during research and development. Because ASC 808 does not provide recognition and measurement guidance, the Company determined that the guidance in ASC 730, Research and Development, was appropriate to analogize to based on the nature of the cost-sharing provisions of the agreement. The Company has concluded that payments to or reimbursements from GSK related to these services will be accounted for as an increase to or reduction of research and development expenses, respectively. The Company also concluded that any payments from GSK related to the profit and loss sharing arrangement (including royalties) contingent upon the commercialization of the products under the Vaccine and Functional Genomics Programs will be analogized to ASC 606 and therefore, will be recognized when the related sales occur. Costs associated with co-development activities performed under the agreement are included in research and development expenses on the consolidated statements of operations, with any reimbursement of costs by GSK reflected as a reduction of such expenses. During the year ended December 31, 2020, the Company recognized $25.4 million as research and development expense under the GSK Agreement. The Company has a payable to GSK of $28.0 million included in accrued liabilities and other liabilities as of December 31, 2020. Brii Biosciences In May 2018, the Company entered into a collaboration, option and license agreement (the “Brii Agreement”) with Brii Biosciences Limited (previously named BiiG Therapeutics Limited) (“Brii Bio Parent”) and Brii Biosciences Offshore Limited (“Brii Bio”), pursuant to which the Company granted to Brii Bio, with respect to up to four of the Company’s programs, an exclusive option to obtain exclusive rights to develop and commercialize compounds and products arising from such programs in China, Taiwan, Hong Kong and Macau (collectively, the “China Territory”) for the treatment, palliation, diagnosis, prevention or cure of acute and chronic diseases of infectious pathogen origin or hosted by pathogen infection (the “Field of Use”). The Company’s HBV siRNA program being developed under the Alnylam Agreement (described below) is included within the Brii Agreement as a program for which Brii Bio may exercise one of its options. In partial consideration for the options granted by the Company to Brii Bio, Brii Bio Parent and Brii Bio granted the Company, with respect to up to four of Brii Bio Parent’s or Brii Bio’s programs, an exclusive option to be granted exclusive rights to develop and commercialize compounds and products arising from such Brii Bio programs in the United States for the Field of Use. The number of options that the Company may exercise for a Brii Bio program is limited to the corresponding number of options that Brii Bio exercises for a Vir program. As partial consideration for the Company’s entry into the Brii Agreement, upon closing of Brii Bio Parent’s Series A preferred stock financing, the Company received ordinary shares equal to 9.9% of the outstanding shares in Brii Bio Parent. As a result of Brii Bio’s right to exercise one of its options for the Company’s HBV siRNA program, under the terms of the Alnylam Agreement, as amended, the Company transferred to Alnylam a specified percentage of such equity consideration allocable to such program as discussed below. With respect to programs for which Brii Bio exercises its options, Brii Bio will be required to pay the Company an option exercise fee for each such Vir program ranging from the mid-single-digit millions up to $20.0 million, determined based on the commercial potential of the licensed program. Brii Bio will also be required to pay regulatory milestone payments on a licensed product-by-licensed product basis ranging from the mid-single-digit millions up to $30.0 million, also determined based on the commercial potential of such program. Following commercialization, Brii Bio will be required to make sales milestone payments based on certain specified levels of aggregate annual net sales of products arising from each licensed program in the China Territory, up to an aggregate of $175.0 million per licensed program. Brii Bio also will pay royalties to the Company that range from the mid-teens to the high-twenties, as described below. Upon exercise of each option for a Brii Bio program, the Company will be required to pay to Brii Bio an option exercise fee ranging from the low tens of millions to up to $50.0 million, determined based on the commercial potential of the licensed program. The Company will be required to make regulatory milestone payments to Brii Bio on a licensed product-by-licensed product basis ranging from the low tens of millions up to $100.0 million, also determined based on the commercial potential of such program. The Company will also be required to make sales milestone payments based on certain specified levels of aggregate annual net sales of products in the United States arising from each licensed program, up to an aggregate of $175.0 million per licensed program. In addition, the Company is obligated under the Brii Agreement to pay Brii Bio tiered royalties based on net sales of products arising from the licensed programs in the United States, and Brii Bio is obligated to pay the Company tiered royalties based on net sales of products arising from the licensed programs in the China Territory. The rates of royalties payable by the Company to Brii Bio, and by Brii Bio to the Company, on net sales range from mid-teens to high-twenties. Each party’s obligations to pay royalties expires, on a product-by-product and territory-by-territory basis, on the latest of 10 years after the first commercial sale of such licensed product in the United States or China Territory, as applicable; the expiration or abandonment of licensed patent rights that cover such product in the United States or China Territory, as applicable; and the expiration of regulatory exclusivity in the United States or the China Territory, as applicable. Royalty rates are subject to specified reductions and offsets. The Brii Agreement will remain in force until the expiration of all options or, if any option is exercised, expiration of all royalty payment obligations for all licensed products within such licensed program, unless terminated in its entirety or on a program-by-program basis by either party. Each party may terminate for convenience all rights and obligations with respect to any program for which it has an option, with 30 days’ written notice (if the terminating party has not exercised an option for such program) or 180 days’ notice (following the exercise of an option for such program). The Brii Agreement may also be terminated by either party for insolvency of the other party, and either party may terminate the Brii Agreement in its entirety or on a program-by-program basis for the other party’s uncured material breach on 60 days’ written notice (or 30 days’ notice following failure to make payment). The Company has determined that Brii Bio Parent and its wholly-owned subsidiary Brii Bio are variable interest entities due to their reliance on future financing and having insufficient equity at risk. However, the Company does not have the power to direct activities that most significantly impact the economic success of these entities and is not considered the primary beneficiary of these entities. Therefore, the Company does not consolidate Brii Bio Parent or Brii Bio. The Company also determined that it does not exercise significant influence over Brii Bio Parent or Brii Bio. The investment in Brii Bio Parent was recorded at its initial estimated fair value of $6.6 million. The Company also recorded a contract liability of $6.6 million within deferred revenue which represents deferred consideration for the four options that the Company granted to Brii Bio. The deferred consideration will be recognized when Brii Bio exercises its options or the options expire. The Company accounts for its investment in Brii Bio Parent’s ordinary shares at cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment in Brii Bio Parent. In February 2020, the Company, Alnylam and Brii Bio Parent executed a share transfer agreement under the terms of the Alnylam Agreement (see Alnylam section below). Under the share transfer agreement, the Company transferred a portion of its ordinary shares held in Brii Bio Parent to Alnylam in connection with the execution of the Brii Agreement. As of December 31, 2020 and 2019, the carrying value of the investment in Brii Bio was $5.7 million and $6.6 million, respectively, which is included in other assets on the consolidated balance sheets. The Company’s maximum exposure to loss under the Brii Agreement is represented by options to acquire licenses to develop and commercialize potential products and future milestone payments. The ultimate expense that the Company incurs under the Brii Agreement cannot be quantified at this time as the amount will vary based on the timing and outcome of research activities. Option Exercise by Brii Bio In June 2020, Brii Bio exercised its option to obtain exclusive rights to develop and commercialize compounds and products arising from VIR-2218 in the China Territory. In consideration of the Company’s grant to Brii Bio of an exclusive license related to VIR-2218 in the China Territory, the Company received a $20.0 million option exercise fee in connection with the option exercise. Also, the Company is eligible to receive the following payments related to VIR-2218 in the China Territory: a $30.0 million regulatory milestone payment, up to $175.0 million in sales-based milestone payments, and royalties on net sales ranging from high-teens to high-twenties. The Company evaluated the transaction under ASC 606 and identified one performance obligation consisting of the license granted to Brii Bio. Under the Brii Agreement, Brii Bio is responsible for performing all research and development activities and the Company does not have any other performance obligations within the context of ASC 606 under the arrangement after the option exercise. The transaction price is determined to be $22.7 million which consists of the $20.0 million option exercise fee and $2.7 million of the deferred revenue allocated to the VIR-2218 option at the inception of the Brii Agreement. The Company determined that the license is considered a functional intellectual property that is a distinct performance obligation. Specifically, the Company believes the license is capable of being distinct, as Brii Bio has the capabilities to develop the license either on its own or by contracting other third-parties. Brii Bio can benefit from the license at the time of grant and therefore, the related performance obligation is satisfied at a point in time. Additionally, all potential future milestones and other payments are constrained because the Company cannot conclude it is probable that a significant reversal in the amount recognized would not occur. The Company will re-evaluate the transaction price in each reporting period. During the second quarter of 2020, the Company recognized the $22.7 million as license revenue from a related party. The Company separately paid $10.0 million, half of the option exercise proceeds, to Alnylam in connection with the Alnylam Agreement that was recognized as research and development expense during the same period. Alnylam October 2017 Agreement In October 2017, the Company entered into the Alnylam Agreement for the development of siRNA products for the treatment of HBV and following the exercise of certain program options, the development and commercialization of siRNA therapeutic products directed to up to four other infectious disease targets selected by the Company. The technology licensed under the Alnylam Agreement forms the basis of the Company’s siRNA technology platform. Under the Alnylam Agreement, the Company obtained a worldwide, exclusive license to develop, manufacture and commercialize the HBV siRNA product candidates, including VIR-2218, for all uses and purposes other than agricultural, horticultural, forestry, aquaculture and other residential applications, such excluded fields, the Excluded Fields. In addition, Alnylam granted the Company an exclusive option, for each of the infectious disease siRNA programs directed to the Company’s selected targets, to obtain a worldwide, exclusive license to develop, manufacture and commercialize siRNA products directed to the target of each such program for all uses and purposes other than the Excluded Fields. On a product-by-product basis for each product arising from the HBV and, following the Company’s option exercise, the infectious disease programs, Alnylam has an exclusive option, exercisable during a specified period prior to the initiation of a Phase 3 clinical trial for each such product, to negotiate and enter into a profit-sharing agreement for such product. The Company and Alnylam are jointly responsible for funding the initial research and development activities for VIR-2218 through the completion of proof of concept trials. Prior to the exercise of the Company’s option for each siRNA program directed to one of the Company’s selected infectious disease targets, Alnylam is responsible for conducting all development activities, at the Company’s expense, in accordance with an agreed upon development plan. Following the Company’s exercise of an option for a program and payment of the program option exercise fee and any outstanding program costs due to Alnylam, the Company is solely responsible, at the Company’s expense (subject to Alnylam’s exercise of a profit-sharing option), for conducting all development, manufacture and commercialization activities for products arising from each such program. If Alnylam exercises a profit-sharing option for a product, the Company will negotiate the terms of such profit-sharing agreement, which will include sharing equally with Alnylam all subsequent costs associated with the development of such product, as well as the profits and losses in connection with such product, subject to reimbursement by Alnylam of a portion of specified development costs in certain circumstances. Under the Alnylam Agreement, the Company paid Alnylam an upfront fee of $10.0 million and issued to Alnylam 1,111,111 shares of the Company’s common stock. Additionally, the receipt of consideration from Brii Bio as discussed above triggered a requirement under the Alnylam Agreement to transfer a portion of the consideration, consisting of equity in Brii Bio Parent, to Alnylam. Accordingly, the Company recognized a liability of $0.8 million which remained outstanding as of December 31, 2019. In February 2020, the Company settled this liability by transferring to Alnylam a specified percentage of its equity consideration received from Brii Bio Parent. Upon the achievement of a certain development milestone, as further discussed below, the Company was obligated to issue shares of the Company’s common stock equal to the lesser of (i) 1,111,111 shares or (ii) a certain number of shares based on the Company’s stock price at the time such milestone is achieved (the “Milestone Shares”). The Company will be required to pay Alnylam up to $190.0 million in the aggregate for the achievement of specified development and regulatory milestones by the first siRNA product directed to HBV, and up to $115.0 million for the achievement of specified development and regulatory milestones by the first product directed to the target of each infectious disease siRNA program for which the Company exercised its option. Following commercialization, the Company will be required to pay to Alnylam up to $250.0 million in the aggregate for the achievement of specified levels of net sales by siRNA products directed to HBV and up to $100.0 million for the achievement of specified levels of net sales by products directed to the target of each infectious disease siRNA program for which the Company exercised its option. The Company may also be required to pay Alnylam tiered royalties at percentages ranging from the low double-digits to mid-teens on annual net sales of HBV products, and tiered royalties at percentages ranging from the high single-digits to the sub-teen double-digits on annual net sales of licensed infectious disease products, in each case subject to specified reductions and offsets. The royalties are payable on a product-by-product and country-by-country basis until the later of the expiration of all valid claims of specified patents covering such product in such country and 10 years after the first commercial sale of such product in such country. The term of the Alnylam Agreement will continue, on a product-by-product and country-by-country basis, until the expiration of all royalty payment obligations under the Alnylam Agreement. If the Company does not exercise its option for an infectious disease program directed to one of its selected targets, the Alnylam Agreement will expire upon the expiration of the applicable option period with respect to such program. However, if Alnylam exercises its profit-sharing option for any product, the term of the Alnylam Agreement will continue until the expiration of the profit-sharing arrangement for such product. The Company may terminate the Alnylam Agreement on a program-by-program basis or in its entirety for any reason on 90 days’ written notice. Either party may terminate the agreement for cause for the other party’s uncured material breach on 60 days’ written notice (or 30 days’ notice for payment breach), or if the other party challenges the validity or enforceability of any patent licensed to it under the Alnylam Agreement on 30 days’ notice. At the inception of the Alnylam Agreement, the Milestone Shares did not meet the net settlement criteria to be accounted for as an embedded derivative. Therefore, there was no liability recorded from the inception of the Alnylam Agreement through September 30, 2019. Upon completion of the Company’s IPO in October 2019, the net settlement criteria of the definition of an embedded derivative had been met for the Milestone Shares. The initial fair value of the embedded derivative was estimated to be $13.6 million and was charged to research and development expense in the fourth quarter of 2019. The estimated fair value of the derivative liability was $12.4 million as of December 31, 2019. On March 10, 2020, the Company achieved the specified development milestone relating to the Milestone Shares. Consequently, the Company remeasured and reclassified the derivative liability to additional paid-in capital. The estimated fair value of the derivative liability was $29.2 million as of March 10, 2020. In addition to these Milestone Shares, the Company paid Alnylam $15.0 million in April 2020 in connection with the achievement of the specified development milestone. Second and Third Amendments In March and April 2020, the Company and Alnylam entered into a second and third amendments to the Alnylam Agreement (as amended, the “Amended Alnylam Agreement”) to expand the parties’ existing collaboration to include the development and commercialization of siRNA products targeting SARS-CoV-2, and potentially other related coronaviruses, and up to three targeting human host factors for SARS-CoV-2 (collectively, the “COVID Collaboration Targets”). Under both amendments, the parties agreed to be each responsible for the pre-clinical development costs incurred by each party in performing its allocated responsibilities under an agreed-upon initial pre-clinical development plan for COV Products. Following the completion of initial pre-clinical development activities, the Company had a pre-agreed program option to progress one or more candidates from the COVID Collaboration Targets into further development, subject to Alnylam’s right to opt-in, during a specified period, to share equally with the Company the profits and losses in connection with development and commercialization of a coronavirus product. In December 2020, the Company and Alnylam entered into a letter amendment (the “Letter Agreement”), amending the Amended Alnylam Agreement, to modify certain funding and governance provisions in connection with the siRNA products directed to the COVID Collaboration Targets, including VIR-2703 (the “COV Target”), and to modify certain rights of each party with respect to products arising from such programs. Pursuant to the Letter Agreement, Alnylam will be responsible for conducting pre-clinical research activities set forth in the existing workplan for the COV Target (the “COV Workplan”) at its discretion and sole expense, and the Company will no longer have the obligation to reimburse Alnylam for any share of costs incurred by Alnylam in conducting activities under the COV Workplan after July 1, 2020. In connection with the Letter Agreement, the Company will no longer have a pre-agreed program option, but, if Alnylam selects a development candidate arising from the COV Workplan, the Company and Alnylam have agreed to negotiate in good faith an agreement with respect to the COV Target and siRNA products directed thereto. If Alnylam terminates the COV Workplan, does not select a development candidate, or the Company is unable to agree upon the terms of a definitive agreement, then the COV Target and related siRNA program will no longer be included within the Amended Alnylam Agreement and all rights to the siRNA program directed to VIR-2703 will revert to Alnylam. Research and Development Expenses Recognized for the Period In addition to the Milestone Shares, $15.0 million milestone payment to Alnylam, and the $10.0 million payment resulting from Brii Bio’s option exercise in the first half of 2020, the Company incurred expenses under the Alnylam Agreement of $ 11.5 million for the year ended December 3 1 , 2020. For the year s ended December 3 1 , 2019 and 2018 , the Company incurred expenses under the Alnylam Agreement of $ 18.1 million and $ 8.3 million, respectively . WuXi Biologics In February 2020, the Company entered into a development and manufacturing collaboration agreement with WuXi Biologics (Hong Kong) Limited (“WuXi Biologics”) (the “WuXi Biologics Collaboration Agreement”), for the clinical development, manufacturing, and commercialization of the Company’s proprietary antibodies developed for SARS-CoV-2. Under the WuXi Biologics Collaboration Agreement, WuXi Biologics will conduct cell-line development, process and formulation development, and initial manufacturing for clinical development. WuXi Biologics will have the right to commercialize products incorporating such antibodies in greater China under an exclusive license granted for the selected antibodies that have been developed. The Company will have the right to commercialize such products in all other markets worldwide. WuXi Biologics will perform mutually agreed development and manufacturing activities, under individual statements of work. In addition, the parties agreed that WuXi Biologics will pay the Company tiered royalties at percentages ranging from the high single-digits to mid-teens on annual net sales of all products sold by WuXi Biologics in greater China. The royalties are payable for a specified, standard royalty term. In addition, if WuXi Biologics sublicenses its commercialization rights to a third party, WuXi Biologics will pay the Company a percentage of the sublicense revenue received from such third party. The WuXi Biologics Collaboration Agreement will continue until the expiration of WuXi Biologics’ payment obligations to the Company, unless terminated earlier. If terminated earlier, the WuXi Biologics Collaboration Agreement may be terminated by (i) the written agreement of both parties, (ii) WuXi Biologics following the one year anniversary of the WuXi Biologics Collaboration Agreement effective date with respect to the entire agreement or on a product by product basis with 90 days’ prior written notice or (iii) by either party if the other party materially breaches the WuXi Biologics Collaboration Agreement and fails to cure such breach within sixty days. Rockefeller University In July 2018, the Company entered into an exclusive license agreement with The Rockefeller University (“Rockefeller”), which was amended in May 2019 and in September 2020 (the “Rockefeller Agreement”). Under the Rockefeller Agreement, Rockefeller granted the Company a worldwide exclusive license under certain patent rights, and a worldwide non-exclusive license under certain materials and know-how covering certain antibody variants relating to a specified mutation leading to enhanced antibody function and utility, to develop, manufacture and commercialize infectious disease products covered by the licensed patents, or that involve the use or incorporation of the licensed materials and know-how, in each case for all uses and purposes for infectious diseases. The Company uses technology licensed under the Rockefeller Agreement in the Company’s antibody platform and the Company’s product candidates VIR-3434 and VIR-7832. The Company paid Rockefeller an upfront fee of $0.3 million for entry into the Rockefeller Agreement, and is required to pay annual license maintenance fees of $1.0 million. In addition, for the achievement of specified development and regulatory milestone events, the Company will be required to pay up to $8.5 million for the first infectious disease product for the HIV indication, up to $7.0 million for each of the first four other infectious disease products with specified projected peak worldwide annual net sales, and up to $3.6 million for any other infectious disease product. Following regulatory approval, the Company will be required to pay commercial success milestones of up

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	8 . Property and Equipment, net Property and equipment, net consists of the following: December 31, 2020 2019 (in thousands) Laboratory equipment $ 16,769 $ 11,986 Computer equipment 556 540 Furniture and fixtures 1,444 1,351 Leasehold improvements 7,274 7,121 Construction in progress 1,135 142 Property and equipment, gross 27,178 21,140 Less accumulated depreciation and amortization (9,232 ) (4,832 ) Total property and equipment, net $ 17,946 $ 16,308 Depreciation and amortization expenses were $4.4 million, $3.3 million and $1.6 million for the years ended December 31, 2020, 2019 and 2018, respectively. Sale-Leaseback Transaction In August 2019, the Company entered into a lease agreement whereby the Company sold various laboratory instruments, furniture, and other equipment for gross proceeds of $1.2 million to a bank and leased them back for a five-year Accrued and Other Liabilities Accrued and other liabilities consist of the following: December 31, 2020 2019 (in thousands) Research and development expenses $ 49,384 $ 12,530 Payroll and related expenses 17,060 9,410 Excess funds payable under grant agreements 3,467 94 Operating lease liabilities, current 3,625 — Restricted stock liability — 1,434 Financing lease obligation, current 265 237 Other professional and consulting expenses 2,595 1,634 Other accrued expenses 540 1,156 Total accrued and other liabilities $ 76,936 $ 26,495

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9 . Lease Agreements The Company has various operating lease arrangements for office and laboratory spaces located in California, Oregon, Missouri, and Switzerland with contractual lease periods expiring between 2021 and 2033. These leases require monthly lease payments that may be subject to annual increases throughout the lease term. Certain lease agreements also provide the Company with the option to renew for additional periods ranging from three months to five years. Most of these renewal options are not considered in the remaining lease term unless it is reasonably certain that the Company will exercise such options. Under one of the operating lease arrangements in California, the Company Throughout the term of the lease agreements, the Company is responsible for paying certain operating costs, in addition to rent, such as common area maintenance, taxes, utilities and insurance. These additional charges are considered variable lease costs and are recognized in the period in which the costs are incurred. The following table contains a summary of the lease costs recognized under ASC 842 and additional information related to operating leases: Year Ended (in thousands) December 31, 2020 Operating lease cost $ 4,591 Short-term lease cost 459 Variable lease cost 2,299 Total least cost $ 7,349 Other Information Weighted average remaining lease term (in years) 10.6 years Weighted average incremental borrowing rate 7.7 % Cash paid for amounts included in the measurement of operating lease liabilities for the year ended December 31, 2020 was $5.1 million and was included in net cash used in operating activities in the Company's consolidated statement of cash flows. During the year ended December 31, 2020, the Company entered into a new facility lease and exercised certain lease extensions, under which the Company obtained $48.5 million of ROU assets in exchange for operating lease liabilities. The maturity of the Company’s operating lease liabilities as of December 31, 2020 was as follows (in thousands): Amounts 2021 $ 6,247 2022 9,725 2023 11,399 2024 10,576 2025 8,054 Thereafter 67,503 Total lease payments 113,504 Less: imputed interest (40,949 ) Less: net tenant improvement allowance yet to be received (10,287 ) Present value of operating lease liabilities $ 62,268 The following amounts were recorded in the consolidated balance sheet as of December 31, 2020 (in thousands): Operating Leases Current operating lease liabilities, net of tenant improvement allowances (1) $ 7,913 Operating ROU assets 61,947 Accrued and other liabilities $ 3,625 Operating lease liabilities, noncurrent 66,556 Total operating lease liabilities $ 70,181 (1) Current portion of lease liabilities recorded in prepaid expenses and other current assets for which the lease incentives to be received exceed the minimum lease payments to be paid over the next twelve months. Rent expense under ASC 840 for the years ended December 31, 2019 and 2018 were Manufacturing and Supply Letter Agreements Letter Agreement, Assignment and Master Services Agreement with Samsung On April 9, 2020, the Company and Samsung Biologics Co., Ltd. (“Samsung”) entered into a binding letter agreement (the “Samsung Letter Agreement”), under which Samsung will perform development and manufacturing services for the Company’s SARS-CoV-2 antibody program. Under the terms of the Samsung Letter Agreement, the Company had committed to purchase a firm and binding capacity reservation for a specified number of manufacturing slots in 2021 and 2022. The Company was obligated to pay a total of approximately $362 million for such capacity reservation on a take-or-pay basis regardless of whether such manufacturing slots are utilized by the Company, subject to annual adjustment based on the Korean Consumer Price Index, which also includes certain fees relating to project management and technology transfer. The amounts were to be payable during 2021 and 2022 and invoiced on a per-batch basis, with shortfalls invoiced at the end of the year in which such shortfall occurs. On August 4, 2020, the Company, GlaxoSmithKline Trading Services Limited (“GSKTSL”) and Samsung entered into an Assignment and Novation Agreement effective as of July 31, 2020 under which the Company assigned and transferred to GSKTSL all of the Company’s right, title, and interest in, to and under the Samsung Letter Agreement, and GSKTSL became the Company’s successor in interest in and to all of the Company’s rights, duties, and obligations in, to and under the Samsung Letter Agreement. On August 4, 2020, GSKTSL entered into a Master Services Agreement with Samsung effective as of July 31, 2020 (the “Samsung MSA”), thereby superseding the Samsung Letter Agreement, and under which, among other things, Samsung will perform development and manufacturing services for clinical and commercial supply of antibody products under the Company’s SARS-CoV-2 antibody program. Letter Agreement, Assignment and Master Services Agreement with WuXi Biologics On June 15, 2020, the Company and WuXi Biologics entered into a binding letter of intent (the “WuXi Biologics Letter Agreement”), under which WuXi Biologics will perform certain development and manufacturing services for the Company’s SARS-CoV-2 antibody program. Under the terms of the WuXi Biologics Letter Agreement, the Company had committed to purchase a firm and binding capacity reservation for the manufacture of a specified number of batches of drug substance of the Company’s SARS-CoV-2 antibody in 2020 and 2021. In addition, the Company had the right to order an additional specified number of batches of drug substance, provided it makes such election by a specified date in the fourth calendar quarter in 2020. WuXi Biologics is obligated to reserve such manufacturing slots on a non-cancellable basis and will manufacture the agreed number of batches of drug substance per an agreed manufacturing schedule. The Company was obligated to pay a total of approximately $130.0 million for such capacity reservation, if all batches are manufactured, inclusive of estimated raw material costs, with between 70% and 80% of the batch production fees owed to WuXi Biologics on a take-or-pay basis regardless of whether such manufacturing slots are utilized by the Company. The amounts were to be payable during 2020 and 2021 and invoiced on a per-batch basis. The SARS-CoV-2 antibody drug substance contemplated to be manufactured per the terms of the WuXi Biologics Letter Agreement will be utilized in connection with progressing the development and commercialization of the SARS-CoV-2 antibody product under the Company’s collaboration with GSK. On August 4, 2020, the Company, GSKTSL and WuXi Biologics entered into an Assignment and Novation Agreement effective as of July 29, 2020 under which the Company assigned and transferred to GSKTSL all of the Company’s right, title, and interest in, to and under the WuXi Biologics Letter Agreement, and GSKTSL became the Company’s successor in interest in and to all of the Company’s rights, duties, and obligations in, to and under the WuXi Biologics Letter Agreement. On August 4, 2020, GSKTSL entered into a non-exclusive Master Services Agreement for Commercial Manufacture of Drug Substance with WuXi Biologics effective as of July 29, 2020 (the “WuXi Biologics MSA”), thereby superseding the WuXi Biologics Letter Agreement, and pursuant to which, among other things, WuXi Biologics will perform development and manufacturing services for clinical and commercial supply of antibody products under the Company’s SARS-CoV-2 antibody program. GSKTSL entered into the WuXi Biologics MSA and Samsung MSA in connection with the performance of the obligations of the Company and GSK, under the GSK Agreement. Per the terms of the GSK Agreement, the Company will continue to be responsible for 72.5% of the costs under each of the WuXi Biologics MSA and Samsung MSA, and GSK will bear 27.5% of such costs under each of the Samsung MSA and the WuXi Biologics MSA, subject to certain conditions and exceptions. Indemnification In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Under such agreements, the Company may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. In addition, the Company has entered into indemnification agreements with its directors and certain officers that may require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. To date, no demands have been made upon the Company to provide indemnification under these agreements, and thus, there are no indemnification claims that the Company is aware of that could have a material effect on the Company’s consolidated balance sheets, consolidated statements of operations, or consolidated statements of cash flows.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	10 . As a result of the Brii Agreement in May 2018, the Company holds a minority equity interest in Brii Bio through its parent company, Brii Bio Parent. Additionally, the Company’s Chief Executive Officer and member of the board of directors as well as another member of the Company’s board of directors serve on Brii Bio Parent’s board of directors. In January 2019, the Company issued 18,202,213 shares of Series B convertible preferred stock to existing Series A-1 preferred stockholders. See further discussion in Note 11—Convertible Preferred Stock.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock	1 1 . Prior to the IPO, under the Company’s amended and restated certificate of incorporation, the Company was authorized to issue two classes of shares: preferred stock and common stock. The preferred stock was issued in series. In June 2018, the Series A-1 and B Preferred Stock Purchase Agreement was amended and restated (the “Amended A&R Series A-1 and B Purchase Agreement”), under which the Company sold an aggregate of 3,222,220 shares of Series A-1 convertible preferred stock at $4.50 per share for gross proceeds of $14.5 million in three closings (the “Additional Closings”): (i) 2,777,776 shares in two closings in June 2018; and (ii) 444,444 shares in July 2018. Under the Amended A&R Series A-1 and B Purchase Agreement, after the Additional Closings, the Company was authorized to sell up to 1,111,121 additional shares of Series A-1 convertible preferred stock in one or more additional closings. In January 2019, under the Amended A&R Series A-1 and B Purchase Agreement, the Company sold an aggregate of 18,202,213 shares of Series B convertible preferred stock at $18.00 per share for net proceeds of $327.5 million in two closings. The Company was authorized to sell up to 4,020,009 additional shares of Series B convertible preferred stock in one or more additional closings. Upon closing of the IPO, all of the outstanding convertible preferred stock automatically converted into 88,112,733 shares of common stock. After the closing of the IPO, there were no shares of convertible preferred stock outstanding.

Convertible Preferred Stock War

Convertible Preferred Stock Warrant Liability	12 Months Ended
	Dec. 31, 2020
Convertible Preferred Stock Warrant Liability [Abstract]
Convertible Preferred Stock Warrant Liability	12. In September 2016, the Company issued a warrant to purchase an aggregate of 244,444 shares of the Company’s Series A-1 convertible preferred stock with an exercise price of $4.50 per share in connection with the termination of a sponsor research agreement. The warrant was fully vested upon the issuance date and had an expiration date of September 11, 2026. The warrant was initially accounted for as a liability and was subject to remeasurement at each reporting period, with changes in estimated fair value recognized as a component of other income (expense), net. Upon the completion of the IPO in October 2019, the warrant automatically converted into a warrant to purchase 244,444 shares of common stock. Therefore, the convertible preferred stock warrant liability was reclassified to additional paid-in capital. In May 2020, the holder exercised its warrant in a cashless exercise for which the Company issued an aggregate of 211,774 shares of common stock.

Stock-Based Awards

Stock-Based Awards	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Awards	1 3 . 2016 Equity Incentive Plan In September 2016, the Company adopted the 2016 Equity Incentive Plan (the “2016 Plan”) for the issuance of incentive stock options (“ISO”), non-qualified stock options (“NSO”), stock appreciation rights (“SARs”), restricted stock and other stock awards, to employees, non-employee directors, and consultants under terms and provisions established by the Company’s board of directors and approved by the stockholders. Awards granted under the 2016 Plan expire no later than ten years from the date of grant. For ISO and NSO, the option price shall not be less than 100% of the estimated fair value on the date of grant. Options granted typically vest over a four-year In conjunction with adopting the 2019 Equity Incentive Plan (the “2019 Plan”), the Company discontinued the 2016 Plan with respect to the new equity awards. 2019 Equity Incentive Plan In September 2019, the Company’s board of directors adopted, with the approval of its stockholders, the 2019 Plan for the issuance of ISO, NSO, SARs, restricted stock, other stock awards and performance cash awards, to employees, non-employee directors, and consultants. The 2019 Plan became effective concurrent with the IPO. Awards granted under the 2019 Plan expire no later than ten years from the date of grant. For ISO and NSO, the option price shall not be less than 100% of the estimated fair value on the date of grant. Options granted typically vest over a four-year 2019 Employee Stock Purchase Plan In September 2019, the Company’s board of directors adopted, with the approval of its stockholders, the 2019 Employee Stock Purchase Plan (the “2019 ESPP”). The 2019 ESPP Plan became effective on the completion of the Company’s IPO. The 2019 ESPP authorizes the issuance of 1,280,000 shares of the Company’s common stock under purchase rights granted to its employees or employees of any of the Company’s designated affiliates. The number of shares of the Company’s common stock reserved for issuance is subject to an automatic increase at each calendar year. Under the 2019 ESPP, the Company may specify offerings with durations of not more than 27 months and may specify shorter purchase periods within each offering. The 2019 ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their earnings, subject to any plan limitations. Unless otherwise determined by the Company’s board of directors, employees can purchase shares at 85% Stock Option Activity Activity under the Company’s stock option plans is set forth below: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (Years) (in thousands) Outstanding at December 31, 2019 7,186,298 $ 5.25 8.5 Granted 4,893,710 $ 32.94 Exercised (1,618,368 ) $ 2.51 Canceled (663,358 ) $ 11.56 Outstanding at December 31, 2020 9,798,282 $ 19.10 8.6 $ 109,272 Vested and expected to vest at December 31, 2020 9,798,282 $ 19.10 8.6 $ 109,272 Vested and exercisable at December 31, 2020 2,462,133 $ 5.40 7.7 $ 52,773 The aggregate intrinsic value of options exercised during the years ended December 31, 2020 and 2019 was $53.1 million and $5.5 million, respectively. The aggregate intrinsic value of options exercised During the years ended December 31, 2020, 2019, and 2018, the estimated weighted-average grant date fair value of the options granted was $25.49, $7.83, and $1.72 per share, respectively. As of December 31, 2020, the Company expects to recognize the remaining unamortized stock-based compensation expense of $117.5 million related to stock options, over an estimated weighted average period of 2.7 years. Stock Options Granted to Employees The fair value of stock options granted to employees was estimated on the date of grant using the Black-Scholes option pricing model using the following assumptions: Year Ended December 31, 2020 2019 2018 Expected term of options (in years) 5.0 – 6.1 5.9 – 6.1 6.0 Expected stock price volatility 88.8% – 108.6% 86.5% – 89.4% 86.4% – 88.0% Risk-free interest rate 0.3% – 1.2% 1.5% – 2.5% 2.5% – 3.0% Expected dividend yield — — — The valuation assumptions were determined as follows: Expected Term— The expected term represents the period that the options granted are expected to be outstanding and is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term) as the Company has concluded that its stock option exercise history does not provide a reasonable basis upon which to estimate expected term. Expected Volatility— The expected volatility was determined by examining the historical volatilities for industry peers and using an average of historical volatilities of the Company’s industry peers as the Company does not have a sufficient historical trading history for its stock. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its stock price becomes available. Risk-Free Interest Rate— The Company based the risk-free interest rate over the expected term of the options based on the constant maturity rate of U.S. Treasury securities with similar maturities as of the date of the grant. Expected Dividend Rate— The expected dividend is zero as the Company has not paid nor does it anticipate paying any dividends on its profit interest units in the foreseeable future. Restricted Stock Activity The following table summarizes restricted stock activity: Number of Shares Weighted Average Fair Value at Date of Grant per Share Unvested as of December 31, 2019 2,075,511 $ 0.95 Vested (1,986,250 ) 0.92 Unvested as of December 31, 2020 89,261 $ 1.48 The shares of restricted stock have not been included in the shares issued and outstanding. In January 2017, the Company entered into a restricted stock purchase agreement with an executive officer and a restricted stock purchase agreement with a director whereby the executive officer and the director purchased an aggregate of 3,624,355 shares of restricted stock. The consideration for the restricted stock was the issuance of promissory notes which are non-recourse in nature and are accounted for as in-substance stock options. The Company measured compensation cost for these in-substance options based on their estimated fair value on the grant date using the Black-Scholes pricing model. The Company recognized compensation cost over the requisite service period with an offsetting credit to additional paid-in capital. In August 2019, per the terms of the notes, the Company received $3.3 million as repayment of the outstanding promissory notes and accrued interest. The Company reduced the restricted stock liability as the common stock vests, which was fully vested as of December 31, 2020. As of December 31, 2020, there was $0.1 million of total unrecognized compensation cost related to unvested restricted stock, all of which is expected to be recognized over a remaining weighted-average period of 0.4 years. Stock-Based Compensation Expense The following table sets forth the total stock-based compensation expense for all awards granted to employees and non-employees, including shares sold through the issuance of non-recourse promissory notes of which all the shares are considered to be options for accounting purposes in the Company’s consolidated statements of operations: Year Ended December 31, 2020 2019 2018 (in thousands) Research and development $ 13,663 $ 3,034 $ 1,056 General and administrative 13,937 5,685 3,997 Total stock-based compensation $ 27,600 $ 8,719 $ 5,053

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Net Loss Per Share	14. Net Loss Per Share As the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share for all periods as the inclusion of all potential common securities outstanding would have been anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: As of December 31, 2020 2019 2018 Convertible preferred stock — — 69,910,520 Options issued and outstanding 9,798,282 7,186,298 5,044,924 Restricted shares subject to future vesting 89,261 2,075,511 4,814,733 Warrants to purchase convertible preferred stock — — 244,444 Warrants to purchase common stock — 244,444 — Total 9,887,543 9,506,253 80,014,621

Defined Benefit Pension and Oth

Defined Benefit Pension and Other Postretirement Plans	12 Months Ended
	Dec. 31, 2020
Defined Benefit Plans And Other Postretirement Benefit Plans Disclosures [Abstract]
Defined Benefit Pension and Other Postretirement Plans	1 5 . Defined Contribution Plan In October 2017, the Company began to sponsor a 401(k) retirement savings plan for the benefit of its employees. Eligible employees may contribute a percentage of their compensation to this plan, subject to statutory limitations. The Company made contributions to the plan for eligible participants, and recorded contribution expenses of $1.8 million, $1.2 million, and $0.7 million for the years ended December 31, 2020, 2019 and 2018, respectively. Postretirement Benefits (Pension Plans) for Humabs The Company’s subsidiary, Humabs, provides its Swiss employees with mandatory cash balance pension benefits whereby employer and employee contributions are accumulated in individual accounts with interest to retirement or withdrawal, if earlier. The benefits are financed through the Swiss Life Collective BVG Foundation with Swiss Life Asset Management through two separate plans. In addition to retirement benefits, the plans provide benefits on death or long-term disability of its employees. The first plan is a defined normal benefit plan which is funded 65% by the Company and 35% by employee contribution to a collective foundation with Swiss Life Asset Management. On retirement, the plan participant will receive his/her accumulated savings, which consist of all contributions paid by the employer and the employees, net of any withdrawals, and the interest granted on those savings at the discretion of the pension foundation. Additional funding requirements may be determined by the pension foundation in case of a severe underfunding. The second plan is a defined management plan. This plan is set up as a collective foundation with Swiss Life Contributions are expressed as an age-related percentage of pensionable salary between limits and are shared between Humabs and its employees. The contributions paid by the Company and employees were immaterial for the year ended December 31, 2020. As of December 31, 2020 and 2019, the Company has $2.9 million and $1.9 million, respectively, of net liability under the pension plans recognized in the consolidated balance sheets. All components of net periodic benefit cost recognized in the consolidated statements of operations during 2020, 2019 and 2018 were immaterial.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	1 6 . Income Taxes Loss before provision for (benefit from) income taxes consists of the following (in thousands): Year Ended December 31, 2020 2019 2018 Domestic $ (309,697 ) $ (138,724 ) $ (110,399 ) Foreign 11,086 (35,805 ) (5,965 ) Total loss before provision for (benefit from) income taxes $ (298,611 ) $ (174,529 ) $ (116,364 ) The components of income tax expense (benefit) consist of the following (in thousands): Year Ended December 31, 2020 2019 2018 Current: Federal $ — $ — $ — State — — — Foreign 106 154 20 106 154 20 Deferred: Federal (21 ) — (445 ) State (31 ) — (55 ) Foreign — — — (52 ) — (500 ) Provision for (benefit from) income taxes $ 54 $ 154 $ (480 ) A reconciliation between the expected income tax provision at the federal statutory rate and the reported income tax benefit is as follows: Year Ended December 31, 2020 2019 2018 U.S. federal statutory income tax rate 21.0 % 21.0 % 21.0 % Foreign tax at less than federal statutory rate 0.9 (0.3 ) (0.1 ) Prior year tax rate adjustment (1.9 ) — — State taxes, net of federal benefit 2.7 2.4 2.0 Research and development tax credit 1.8 2.0 2.2 Acquired IPR&D — — (2.9 ) Permanent items 1.3 (0.8 ) (0.4 ) Changes in valuation allowance - Humabs IP transfer (1.9 ) — — Changes in valuation allowance (23.4 ) (24.3 ) (21.4 ) Other (0.5 ) (0.1 ) — Effective income tax rate 0.0 % (0.1 )% 0.4 % The tax effects of temporary differences that give rise to significant portions of the Company’s deferred tax assets and liabilities as of December 31, 2020 and 2019, are related to the following: December 31, 2020 2019 (in thousands) Deferred tax assets: Net operating loss carryforwards $ 117,433 $ 67,493 Research and development tax credit carryforward 12,246 6,978 Equity compensations 4,193 1,514 Reserves and accruals 10,804 6,988 Lease liabilities 16,184 — Intangible assets 23,006 9,733 Deferred tax assets 183,866 92,706 Deferred tax liabilities: ROU assets (16,147 ) — Property and equipment (2,570 ) (1,553 ) IPR&D (8,511 ) (8,647 ) Deferred tax liabilities (27,228 ) (10,200 ) Valuation allowance (159,891 ) (85,811 ) Net deferred tax liabilities $ (3,253 ) $ (3,305 ) The Company has incurred significant tax losses since inception. Based on the available objective evidence, the Company cannot conclude it is more likely than not that the net deferred tax assets will be fully realizable. Accordingly, the Company has provided a valuation allowance against its net deferred tax assets. For the years ended December 31, 2020, 2019 and 2018, the valuation allowance increased by $74.1 million, $42.3 million, and $26.0 million, respectively. As of December 31, 2020, the Company has net operating loss carryforwards of $483.7 million for federal purposes and $216.8 million for state tax purposes. If not utilized, these carryforwards will begin expiring in 2035 for federal and in 2031 for state tax purposes. The federal net operating losses (“NOLs”) generated after December 31, 2017, have an infinite carryforward period and subject to 80% deduction limitation based upon pre-NOL deduction taxable income. As of December 31, 2020, the Company also has net operating loss carryforwards of $17.8 million for Swiss tax purposes, which begin expiring in 2022 and no net operating loss carryforward for Australian tax purposes. Under the Tax Reform Act of 1986, the amounts of and benefits from net operating loss carryforwards may be impaired or limited in certain circumstances. Events which cause limitations in the amount of net operating losses that the Company may utilize in any one year include, but are not limited to, a cumulative ownership change of more than 50% over a three-year period. The impact of any limitations that may be imposed due to such ownership changes has not yet been determined. As of December 31, 2020, the Company has research tax credit carryforwards of $9.1 million and $7.0 million for federal and state tax purposes, respectively. If not utilized, the federal carryforward will expire in various amounts beginning in 2036. The California credits can be carried forward indefinitely. If not utilized, Oregon carryforward will expire starting 2021. The Company has not undertaken a detailed analysis of all amounts claimed as research credits for federal or state tax purposes. As a result, amounts ultimately realized for research credits were included in the Company’s consideration of uncertain tax benefits. Uncertain Tax Positions As of December 31, 2020 and 2019, the Company had an unrecognized tax benefit of $4.9 million and $2.7 million, respectively, related to transfer pricing and research and development tax credits. No amount of unrecognized tax benefits as of December 31, 2020, if recognized, would reduce the Company’s effective tax rate because the benefits would be in the form of tax credit carryforwards, which would attract a full valuation allowance. There are no provisions for which it is reasonably possible that the total amounts of unrecognized tax benefits will significantly increase or decrease within 12 months of the reporting date. Because the statute of limitations does not expire until after the net operating loss and credit carryforwards are actually used, the statutes are still open on calendar years ending December 31, 2020 forward for federal and state purposes. The Company did not recognize any expense for interest and penalties related to uncertain tax positions during 2020, 2019 and 2018, and the Company does not have any amounts related to interest and penalties accrued at December 31, 2020. The Company files U.S. federal, state, Switzerland and Australia tax returns. The Company’s tax years remain open for all years. As of December 31, 2020, the Company was not under examination by the Internal Revenue Service or any state or foreign tax jurisdiction. A reconciliation of the beginning and ending amounts of the liability for uncertain tax positions is as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Gross unrecognized tax benefits at January 1 $ 2,725 $ 2,404 $ 272 Addition for tax positions taken in the prior years — 133 32 Reduction for tax positions taken in the prior years (588 ) (1,596 ) (215 ) Addition for tax positions taken in current year 2,740 1,784 2,315 Gross unrecognized tax benefits at December 31 $ 4,877 $ 2,725 $ 2,404

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	1 7 . Selected Quarterly Financial Data (Unaudited) Three Months Ended March 31, 2020 June 30, 2020 September 30, 2020 December 31, 2020 (in thousands) Total revenue $ 5,718 $ 66,988 $ 1,928 $ 1,734 Total operating expenses $ (77,628 ) $ (96,039 ) $ (89,543 ) $ (110,138 ) Net loss $ (77,240 ) $ (31,167 ) $ (84,609 ) $ (105,649 ) Net loss per share, basic $ (0.71 ) $ (0.27 ) $ (0.67 ) $ (0.83 ) Net loss per share, diluted $ (0.71 ) $ (0.27 ) $ (0.67 ) $ (0.83 ) Three Months Ended March 31, 2019 June 30, 2019 September 30, 2019 December 31, 2019 (in thousands) Total revenue $ 3,661 $ 2,047 $ 1,403 $ 980 Total operating expenses $ (34,431 ) $ (37,817 ) $ (49,083 ) $ (64,739 ) Net loss $ (28,670 ) $ (33,928 ) $ (48,314 ) $ (63,771 ) Net loss per share, basic $ (3.19 ) $ (3.64 ) $ (4.60 ) $ (0.69 ) Net loss per share, diluted $ (3.19 ) $ (3.64 ) $ (4.60 ) $ (0.71 )

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	1 8 . 2021 Expanded GSK Collaboration Preliminary Collaboration Agreement On February 14, 2021, the Company and GSK entered into a binding preliminary collaboration agreement (the “Preliminary Collaboration Agreement”), pursuant to which the parties agreed to expand their 2020 collaboration relating to research and development of therapies for coronaviruses, to include collaboration on three separate programs: (1) a program to research, develop and commercialize mAbs for the prevention, treatment or prophylaxis of the influenza virus; (2) an expansion of the parties’ current Functional Genomics Program to focus on functional genomics screens directed to targets associated with respiratory viruses; and (3) additional programs to develop neutralizing mAbs directed to up to three non-influenza target pathogens selected by GSK. For a period of three years following the effective date of the Preliminary Collaboration Agreement, the parties will conduct certain research and development activities under mutually agreed development plans and associated budgets for the programs within the expanded collaboration. The parties will continue to negotiate a more detailed collaboration agreement (the “Definitive Collaboration Agreement”), including more detailed financial terms, as well as operational provisions and consequences of any ongoing collaboration program as a result of a change of control of the Company. GSK will make an upfront payment to the Company of $225 million, 50% of which will become payable at the effective date of the Preliminary Collaboration Agreement and 50% of which will become payable at the effective date of the Definitive Collaboration Agreement. 2021 Stock Purchase Agreement Concurrently with the execution of the Preliminary Collaboration Agreement, the Company entered into a stock purchase agreement (the “2021 Stock Purchase Agreement”) with GGL, pursuant to which GGL will purchase shares of the Company’s common stock for an aggregate purchase price of approximately $120.0 million. The consummation of the transactions under each of the Preliminary Collaboration Agreement and the 2021 Stock Purchase Agreement are subject to the satisfaction of customary closing conditions, including the expiration or termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended; provided, however, that in no event will the closing of the transactions under the 2021 Stock Purchase Agreement occur prior to the Data End Date. The “Data End Date” means the tenth trading day immediately following the date that the Company makes a public announcement regarding initial Phase 3 results for the COMET-ICE (COVID-19 Monoclonal antibody Efficacy Trial—Intent to Care Early) trial for VIR-7831. Xencor amendments In February 2021, the Company and Xencor executed amendments to the 2019 Xencor Agreement and the 2020 Xencor Agreement primarily to expand the scope of the licensed technology under each agreement, which may increase the Company’s royalty payment obligations in certain circumstances. Under the amended agreements, the Company will be obligated to pay Xencor tiered royalties on net sales ranging from low- to mid-single-digits under the amended 2019 Xencor Agreement and at the mid-single-digits under the amended 2020 Xencor Agreement. Milestone Payable under the TomegaVax Letter Agreement In February 2021, pursuant to the TomegaVax Letter Agreement, the Company achieved the specified share price resulting in a $10.0 million payable to TomegaVax’s former stockholders within 90 business days.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and include all adjustments necessary for the fair presentation of the Company’s financial position for the periods presented. The consolidated financial statements include the accounts of Vir and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated upon consolidation.
Foreign Currency	Foreign Currency The functional currency of the Company’s foreign subsidiaries is the U.S. dollar. Monetary assets and liabilities of foreign subsidiaries are translated into U.S. dollars at period-end exchange rates and non-monetary assets and liabilities are translated to U.S. dollars using historical exchange rates. Revenue and expenses are translated at average rates throughout the respective periods. Transaction gains and losses are included in other income (expense), net on the consolidated statements of operations and were immaterial for the years ended December 31, 2020, 2019 and 2018.
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expense during the reporting periods. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could materially differ from those estimates.
Segments	Segments The Company has one operating segment. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for purposes of allocating resources.
Concentration of Credit Risk, Credit Loss and Other Risks and Uncertainties	Concentration of Credit Risk, Credit Loss and Other Risks and Uncertainties With the global spread of the current COVID-19 pandemic, the Company has implemented a number of plans and policies designed to address and mitigate the impact of the COVID-19 pandemic on its business. The Company anticipates that the COVID-19 pandemic will have an impact on the clinical development timelines for some of its clinical programs. The extent to which the COVID-19 pandemic impacts the Company’s business, clinical development and regulatory efforts, corporate development objectives and the value of and market for its common stock, will depend on future developments that are highly uncertain and cannot be predicted with confidence at this time, such as the ultimate duration of the pandemic, travel restrictions, quarantines, social distancing and business closure requirements in the United States, Europe and other countries, and the effectiveness of actions taken globally to contain and treat the disease. In addition, the Company is subject to a number of other challenges and risks similar to other biopharmaceutical companies in the early stage, including, but not limited to, the need to obtain adequate additional funding, possible failure of preclinical testing or clinical trials, the need to obtain marketing approval for its product candidates, competitors developing new technological innovations, the need to successfully commercialize and gain market acceptance of the Company’s products and protection of proprietary technology. If the Company does not successfully obtain regulatory approval, commercialize or partner any of its product candidates, it will be unable to generate revenue from product sales or achieve profitability. Also, to the extent the current COVID-19 pandemic adversely affects the Company’s business and results of operations, it may also have the effect of heightening many of the other risks and uncertainties discussed above. Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents and short and long-term investments. Cash and cash equivalents are deposited in checking and sweep accounts at a financial institution. Such deposits may, at times, exceed federally insured limits. The Company has not experienced any losses on its deposits of cash and cash equivalents. The Company’s investment policy limits investments to certain types of securities issued by the U.S. government, its agencies and institutions with investment-grade credit ratings and places restrictions on maturities and concentration by type and issuer. The Company is exposed to credit risk in the event of a default by the financial institutions holding its cash, cash equivalents and investments, and issuers of the investments to the extent recorded on the consolidated balance sheets. As of December 31, 2020, the Company has no off-balance sheet concentrations of credit risk. Effective January 1, 2020, the Company adopted Accounting Standards Update (ASU) 2016-13, Financial Instruments — Credit Losses, (Topic 326): Measurement of Credit Losses on Financial Instruments, which changed the impairment model for most financial assets and certain other instruments. For receivables, the Company uses a new forward-looking expected loss model that generally results in the earlier recognition of allowances for losses. For available-for-sale debt securities with unrealized losses, the losses are recognized as allowances rather than as reductions in the amortized cost of the securities. The Company’s expected loss allowance methodology for the receivables is developed using historical collection experience, current and future economic market conditions, a review of the current aging status and financial condition of the entities. Specific allowance amounts are established to record the appropriate allowance for customers that have a higher probability of default. Balances are written off when determined to be uncollectible. The Company’s expected loss allowance methodology for the debt securities is developed by reviewing the extent of the unrealized loss, the size, term, geographical location, and industry of the issuer, the issuers’ credit ratings and any changes in those ratings, as well as reviewing current and future economic market conditions and the issuers’ current status and financial condition. The Company considered the current and expected future economic and market conditions surrounding the COVID-19 pandemic and determined that the estimate of credit losses was not significantly impacted. The adoption of the guidance did not have a material impact on the consolidated financial statements and related disclosures and there was no allowance for losses on available-for-sale debt securities which were attributable to credit risk for the year ended December 31, 2020.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash and cash equivalents. Cash equivalents, which consist of amounts invested in money market funds, are stated at fair value.
Investments	Investments Investments include available-for-sale securities and are carried at estimated fair value. The Company’s valuations of marketable securities are generally derived from independent pricing services based on quoted prices in active markets for similar securities at period end. Generally, investments with original maturities beyond three months at the date of purchase and which mature at, or less than 12 months from, the consolidated balance sheet date are considered short-term investments, with all others considered to be long-term investments. Unrealized gains and losses deemed temporary in nature are reported as a component of accumulated comprehensive income (loss). The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in interest income on the consolidated statements of operations. The Company, through its investment in Brii Biosciences Limited, holds privately held equity securities in which the Company does not have a controlling interest or significant influence. The Company’s investment in Brii Biosciences Limited is recorded at cost and adjusted for impairments and observable price changes with the same or similar security from the same issuer. The valuation of the Company’s investment in Brii Biosciences Limited utilizes significant unobservable inputs or data in an inactive market and the valuation requires the Company’s judgment due to the absence of market prices and inherent lack of liquidity. Additionally, the determination of whether an orderly transaction is for the same or similar investment requires significant management judgment including the nature of the rights and obligations of its investments, the extent to which differences in those rights and obligations would affect the fair values of those investments, and the impact of any differences based on the stage of operational development of the investee. See Note 7—Collaboration and License Agreements for additional information on the Company’s investment in Brii Biosciences Limited.
Restricted Cash and Cash Equivalents	Restricted Cash and Cash Equivalents Restricted cash and cash equivalents represent money market funds to secure standby letters of credit and security deposits with financial institutions, both under office and laboratory space lease agreements. Additionally, funds received from certain grants are restricted as to their use and are therefore classified as restricted cash and cash equivalents.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized over the lesser of their useful lives or the remaining life of the lease. When assets are retired or otherwise disposed of, the cost and related accumulated depreciation and amortization are removed from the balance sheet and the resulting gain or loss is reflected in operations in the period realized. Maintenance and repairs are charged to operations as incurred. The Company reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparing the carrying amount to the future net undiscounted cash flows which the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the asset. No material impairment losses have been incurred to date.
Acquired Intangible Assets	Acquired Intangible Assets The Company’s intangible assets were acquired via business combinations or asset acquisitions. Indefinite-lived intangible assets represent the estimated fair value assigned to in-process research and development (“IPR&D”) acquired in a business combination. The Company reviews indefinite-lived intangible assets for impairment at least annually or more frequently if events or changes in circumstances indicate that the carrying value of the assets might not be recoverable. If the carrying value of an indefinite-lived intangible asset exceeds its fair value, then it is written down to its adjusted fair value. As of December 31, 2020, there have been no such impairments. For IPR&D, if a product candidate derived from the indefinite-lived intangible asset is developed and commercialized, the useful life will be determined, and the carrying value will be amortized prospectively over that estimated useful life. Alternatively, if a product candidate is abandoned, the carrying value of the intangible asset will be charged to research and development expenses. IPR&D assets acquired as part of an asset acquisition are recorded at cost and expensed immediately if they have no alternative future uses. Finite-lived intangible assets acquired are initially recognized at their fair value at the acquisition date. Amortization is computed using the straight-line method over the estimated useful lives of the respective finite-lived intangible assets, generally seven to 15 years. Finite-lived intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable.
Goodwill	Goodwill Goodwill represents the excess of the purchase price over the estimated fair value of the net tangible and intangible assets acquired in a business combination. The Company tests goodwill for impairment at least annually or more frequently if events or changes in circumstances indicate that this asset may be impaired.
Revenue Recognition	Revenue Recognition Grant Revenue Grants received, including cost reimbursement agreements, are assessed to determine if the agreement should be accounted for as an exchange transaction or a contribution. An agreement is accounted for as a contribution if the resource provider does not receive commensurate value in return for the assets transferred. Contributions are recognized as grant revenue when all donor-imposed conditions have been met. License and Cont . ract Revenue In accordance with Accounting Standards Codification (“ASC”) Topic 606, Revenue from Contracts with Customers (“ASC 606”), the Company recognizes revenue when the Company’s customer obtains control of promised goods or services, in an amount that reflects the consideration which the Company expects to receive in exchange for those goods and services. To determine revenue recognition for arrangements within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when or as the Company satisfies a performance obligation. For collaborative arrangements that fall within the scope of ASC 808, Collaborative Arrangements (“ASC 808”), the Company first determines which elements of the collaboration are deemed to be a performance obligation with a customer within the scope of ASC 606. For elements of collaboration arrangements that are accounted for pursuant to ASC 808 and are not subject to the guidance in ASC 606, the Company applies the revenue recognition model under ASC 606 or other guidance, as deemed appropriate. The Company has entered into a number of license and collaboration agreements that fall within the scope of ASC 606. The Company evaluates the promised goods or services in these agreements to determine which ones represent distinct performance obligations. These agreements may include the following types of promised goods or services: (i) grants of licenses, (ii) performance of research and development services, and (iii) participation on joint research and/or development committees. They also may include options to obtain licenses to the Company’s intellectual property. Prior to recognizing revenue, the Company makes estimates of the transaction price, including variable consideration that is subject to a constraint. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur and when the uncertainty associated with the variable consideration is subsequently resolved. These estimates are re-assessed each reporting period as required. These agreements may include the following types of consideration: non-refundable upfront payments, reimbursement for research services, research, development or regulatory milestone payments, and royalty and commercial sales milestone payments. If there are multiple distinct performance obligations, the Company allocates the transaction price to each distinct performance obligation based on their estimated standalone selling prices. For performance obligations satisfied over time, the Company estimates the efforts needed to complete the performance obligation and recognizes revenue by measuring the progress towards complete satisfaction of the performance obligation using an input measure. For arrangements that include sales-based royalties, including commercial milestone payments based on pre-specified level of sales, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). Achievement of these royalties and commercial milestones may solely depend upon performance of the licensee.
Research and Development Expenses	Research and Development Expenses To date, research and development expenses have related primarily to discovery efforts and preclinical and clinical development of product candidates. Research and development expenses are recognized as incurred and payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods or services are received. Research and development expenses include expenses related to license and collaboration agreements; contingent consideration from business acquisitions; personnel-related expenses, including salaries, benefits, and stock-based compensation for personnel contributing to research and development activities; expenses incurred under agreements with third-party contract manufacturing organizations, contract research organizations, and consultants; clinical costs, including laboratory supplies and costs related to compliance with regulatory requirements; and other allocated expenses, including expenses for rent, facilities maintenance, and depreciation and amortization. The Company has and may continue to acquire the rights to develop and commercialize new product candidates from third parties. Upfront payments and research and development milestone payments made in connection with acquired license or product rights are expensed as incurred, provided that they do not relate to a regulatory approval milestone or assets acquired in a business combination. The Company’s expense accruals for clinical trials and manufacturing are based on estimates of contracted services provided by third-party vendors not yet billed. When billing terms under these contracts do not coincide with the timing of when the work is performed, the Company is required to make estimates of its outstanding obligations to those third parties as of the period end. The accrual estimates are based on a number of factors, including the Company’s knowledge of the research and development programs and clinical manufacturing activities, the status of the programs and activities, invoicing to date, and the provisions in the contracts. The Company obtains information regarding unbilled services directly from these service providers and performs procedures to support its estimates based on its internal understanding of the services provided to date. However, the Company may also be required to estimate these services based on information available to its internal clinical and manufacturing administrative staff if such information is not able to be obtained timely from its service providers.
Stock-based Compensation	Stock-based Compensation The Company recognizes stock-based compensation to employees and non-employees over the requisite service period based on the estimated grant-date fair value of the awards. The Company calculates the fair value of stock options using the Black-Scholes valuation model. Stock-based compensation is recognized using the straight-line method for awards that vest only upon the employee’s or non-employee’s continued service to the Company. Forfeitures are recognized as they occur.
Acquisitions	Acquisitions Business combinations are accounted for using the acquisition method of accounting. Under the acquisition method, assets acquired, including IPR&D projects, and liabilities assumed are recorded at their respective fair values as of the acquisition date. Any excess fair value of consideration transferred over the fair value of the net assets acquired is recorded as goodwill. Contingent consideration obligations incurred in connection with the business combination are recorded at their fair values on the acquisition date and are remeasured each subsequent reporting period until the related contingencies are resolved and are classified as contingent consideration on the consolidated balance sheets. The changes in fair values of contingent consideration related to the achievement of various milestones related to product candidates are recorded within research and development expense. When the Company determines that entities acquired do not meet the definition of a business, the transaction is accounted for as an acquisition of assets. Therefore, the consideration paid to acquire IPR&D is expensed, and no goodwill is recorded. Any contingent consideration is generally recognized only when it becomes payable or is paid.
Embedded Derivatives	Embedded Derivatives The Company evaluates its acquisitions, collaborative arrangements and other business development transactions to determine if embedded components of these contracts meet the definition of a derivative under ASC 815, Derivatives and Hedging. In general, embedded derivatives are required to be bifurcated from the host instrument if (i) the embedded feature is not clearly and closely related to the host contract and (ii) the embedded feature, if considered a freestanding instrument, meets the definition of a derivative. Embedded derivatives are reported on the consolidated balance sheets at their estimated fair values. Contingent consideration related to asset acquisitions that meet the definition of an embedded derivative is classified as contingent consideration on the consolidated balance sheets. Any change in estimated fair values, as determined at each measurement period, are recorded in the consolidated statements of operations based on the nature of the related contingencies.
Leases	Leases In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2016-02, Leases (“ASC 842”). ASC 842 requires lessees to recognize all leases, including operating leases, on the balance sheet as a right-of-use (“ROU”) asset and a lease liability, unless the lease is a short-term lease, defined as having a term of 12 months or less. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements. In issuing ASU 2018-11, the FASB decided to provide another transition method by allowing entities to initially apply the new leases standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. ASC 842 is effective for the Company for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020, with early adoption permitted. The Company early adopted the standard on January 1, 2020 using the optional modified retrospective transition method by recognizing a cumulative effect adjustment to the opening balance of accumulated deficit as of that date. Results for the year ended December 31 , 2020 are presented under ASC 842. The prior period amounts were not adjusted and continue to be reported in accordance with previous lease guidance, ASC 840, Leases. The Company elected the package of practical expedients allowed under ASC 842, which permits the Company to account for its existing operating leases as operating leases under the new guidance, without reassessing the Company’s prior conclusions about lease identification, lease classification and initial direct cost. Adoption of ASC 842 resulted in the recognition of operating lease ROU assets and operating lease liabilities of $16.8 million and $17.5 million, respectively, on the Company’s consolidated balance sheet as of January 1, 2020. The difference between the ROU assets and lease liabilities is attributed to the elimination of deferred rent. The adoption of the new standard did not have an impact on the Company's beginning accumulated deficit or statement of operations. The Company determines if an arrangement is or contains a lease at inception by assessing whether the arrangement contains an identified asset and whether it has the right to control the identified asset. ROU assets represent the Company's right to use an underlying asset for the lease term and lease liabilities represent the Company's obligation to make lease payments arising from the lease. Lease liabilities are recognized at the lease commencement date based on the present value of future lease payments over the lease term. ROU assets are based on the measurement of the lease liability and also include any lease payments made prior to or on lease commencement and exclude lease incentives and initial direct costs incurred, as applicable. On the lease commencement date, the Company estimates and includes in its lease payments any lease incentive amounts based on future events when (1) the events are within the Company’s control and (2) the event triggering the right to receive the incentive is deemed reasonably certain to occur. If the lease incentive received is greater or less than the amount recognized at lease commencement, the Company recognizes the difference as an adjustment to right-of-use asset and/or lease liability, as applicable. As the implicit rate in the Company's leases is generally unknown, the Company uses an incremental borrowing rate estimated based on the information available at the lease commencement date in determining the present value of future lease payments. When calculating its estimated incremental borrowing rates, the Company considers its credit risk, the lease term, the total lease payments and the impact of collateral, as necessary. The lease terms may include options to extend or terminate the lease when the Company is reasonably certain it will exercise such options. ROU assets and lease liabilities are remeasured upon certain modifications to leases using the present value of remaining lease payments and estimated incremental borrowing rate upon lease modification. Rent expense for the Company's operating leases is recognized on a straight-line basis within operating expenses over the reasonably assured lease term. The Company elected to not separate lease and non-lease components for any leases within its existing classes of assets and, as a result, accounts for the lease and non-lease components as a single lease component. The Company has also elected to not apply the recognition requirement to any leases within its existing classes of assets with a term of 12 months or less.
Pension Benefits	Pension Benefits Accounting for the defined pension benefit plan for the Company’s Swiss subsidiary requires actuarial valuations based on significant assumptions for discount rates and expected long-term rates of return on plan assets. These and other assumptions such as salary growth, retirement, and mortality rates are evaluated and selected based on expectations or actual experience during each remeasurement date. Actual results in any given year may differ from those estimated because of economic and other factors. The Company recognizes a liability for the underfunded status of its defined benefit pension plan as a component of other long-term liabilities. Actuarial gains or losses and prior service costs or credits are deferred in accumulated other comprehensive income (loss) and amortized over the remaining service attribution periods of the employees under the corridor method.
Income Taxes	Income Taxes The Company uses the asset and liability method of accounting for income taxes. Current income tax expense or benefit represents the amount of income taxes expected to be payable or refundable for the current year. Deferred income tax assets and liabilities are determined based on differences between the financial statement reporting and tax bases of assets and liabilities and net operating losses and credit carryforwards and are measured using the enacted tax rates and laws that will be in effect when such items are expected to reverse. Deferred income tax assets are reduced, as necessary, by a valuation allowance when management determines it is more likely than not that some or all of the tax benefits will not be realized. The Company’s tax positions are subject to income tax audits. The Company recognizes the tax benefit of an uncertain tax position only if it is more likely than not that the position is sustainable upon examination by the taxing authority, based on the technical merits. The tax benefit recognized is measured as the largest amount of benefit which is more likely than not to be realized upon settlement with the taxing authority. The Company evaluates uncertain tax positions on a regular basis. The evaluations are based on several factors, including changes in facts and circumstances, changes in tax law, correspondence with tax authorities during the course of the audit, and effective settlement of audit issues. The provision for income taxes includes the effects of any accruals that the Company believes are appropriate, as well as any related net interest and penalties.
Net Loss Per Share	Net Loss Per Share Basic net loss per common share is computed by dividing the net loss by the weighted-average number of common shares outstanding during the period, without consideration of common stock equivalents. Diluted net loss per common share is computed by dividing the net loss by the sum of the weighted average number of common shares outstanding during the period plus any potential dilutive effects of common stock equivalents outstanding during the period calculated in accordance with the treasury stock method. Diluted net loss per share is the same as basic net loss per share since the effect of potentially dilutive securities is anti-dilutive.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other: Simplifying the Test for Goodwill Impairment (“ASU 2017-04”), which simplifies the current requirements for testing goodwill for impairment by eliminating the second step of the two-step impairment test to measure the amount of an impairment loss. ASU 2017-04 is effective for the Company’s interim and annual reporting periods beginning after December 31, 2021. The Company early adopted ASU 2017-04 on January 1, 2020 and the adoption had no impact on its consolidated financial statements. In August 2018, the FASB issued ASU 2018‑13, Fair Value Measurement (Topic 820) (“ASU 2018-13”), which modifies, removes and adds certain disclosure requirements on fair value measurements. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The Company adopted ASU 2018-13 on January 1, 2020 and the adoption resulted in additional disclosures related to the Company’s Level 3 financial instruments. See Note 3—Fair Value Measurements. In August 2018, the FASB issued ASU No. 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans (“ASU 2018-14”), which removes certain disclosures and added additional disclosures around weighted-average interest crediting rates for cash balance plans and explanation for significant gains and losses related to change in the benefit obligation for the period. The ASU will be effective for fiscal years ending after December 15, 2020 with a retrospective application for all periods presented. The Company adopted ASU 2018-14 at December 31, 2020 and the adoption had no material impact on its notes to consolidated financial statements. In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606 (“ASU 2018-18”). The amended guidance precludes presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. The new guidance is effective for the Company for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. The Company adopted ASU 2018-18 as of January 1, 2020 and the adoption had no impact on the consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13”), which requires the measurement and recognition of expected credit losses for financial assets held at amortized cost, including the Company’s financial instruments. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss methodology, which is known as the current expected credit loss, or CECL model, which generally results in more timely recognition of credit losses. The CECL model applies to most debt instruments (other than those measured at fair value), trade and other receivables, financial guarantee contracts, and loan commitments. In April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments (“ASU 2019-04”). ASU 2019-04 modified the accounting for available-for-sale debt securities, which must be individually assessed for credit losses when fair value is less than the amortized cost basis. As the Company is no longer an emerging growth company as of December 31, 2020, the Company is required to adopt Topic 326 in its consolidated financial statements, effective on January 1, 2020. The adoption of the guidance did not have a material impact on the consolidated financial statements and related disclosures and there was no allowance for losses on available-for-sale debt securities attributable to credit risk for the year ended December 31, 2020.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Summary of Financial Assets Measured at Fair Value on a Recurring Basis	The following tables summarize the Company’s Level 1 and Level 2 financial assets measured at fair value on a recurring basis by level within the fair value hierarchy: December 31, 2020 Valuation Hierarchy Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value (in thousands) Assets: Money market funds (1) Level 1 $ 421,835 $ — $ — $ 421,835 U.S. government treasuries Level 2 300,201 91 (6 ) 300,286 Total financial assets $ 722,036 $ 91 $ (6 ) $ 722,121 (1) Includes $14.9 million of restricted cash equivalents. December 31, 2019 Valuation Hierarchy Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value (in thousands) Assets: Money market funds (1) Level 1 $ 106,127 $ — $ — $ 106,127 U.S. government treasuries (2) Level 2 298,256 140 (5 ) 298,391 Bank time deposits Level 2 2,500 — — 2,500 Total financial assets $ 406,883 $ 140 $ (5 ) $ 407,018 (1) Includes $13.5 million of restricted cash equivalents. (2) Includes $24.3 million classified as long-term investments
Summary of Changes in Estimated Fair Value of Financial Liabilities	The following table sets forth the changes in the estimated fair value of the Company’s Level 3 financial liabilities (in thousands): Contingent Consideration Derivative Liability Total Balance at December 31, 2019 $ 17,580 $ 12,449 $ 30,029 Changes in fair value 38,394 16,796 55,190 Payment of contingent consideration related to Humabs acquisition (20,000 ) — (20,000 ) Reclassification of derivative liability to additional paid-in capital upon achievement of development milestone — (29,245 ) (29,245 ) Balance at December 31, 2020 $ 35,974 $ — $ 35,974
Humabs | Clinical and Regulatory Milestones
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Estimated Fair Value of Significant Unobservable Inputs	As of December 31, 2020, the Company calculated the estimated fair value of the remaining clinical and regulatory milestones using the following significant unobservable inputs: Unobservable input Value or Range (Weighted-Average) 1 Discount rates 7% - 9% (8%) Probability of achievement 14% - 32% (27%) (1) Unobservable inputs were weighted based on the relative fair value of the underlying milestones.
Humabs | Commercial Milestones
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Estimated Fair Value of Significant Unobservable Inputs	As of December 31, 2020, the Monte Carlo simulation assumed a commercial product launch and associated discrete revenue forecast, as well as the following significant unobservable inputs: Unobservable input Value or Range (Weighted-Average) 1 Volatility 60% Discount rate 11% Probability of achievement 14% - 32% (28%)
TomegaVax
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Estimated Fair Value of Significant Unobservable Inputs	As of December 31, 2020, the fair value of the contingent consideration was estimated using the following significant unobservable inputs: Unobservable input Range (Weighted-Average) 1 Volatility 85% Discount rates 0% - 0.1% (0.1%) (1) Unobservable inputs were weighted based on the relative fair value of the underlying milestones.

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The following table summarizes the carrying amount of the Company’s finite-lived intangible assets (in thousands): December 31, Weighted- Average Remaining Useful 2020 2019 Life (Years) Developed technology $ 7,000 $ 7,000 6.6 Contract-based intangible asset 502 — 14.9 Finite-lived intangible assets, gross 7,502 7,000 Less accumulated amortization (3,581 ) (2,539 ) Less impairment of intangible assets (832 ) — Finite-lived intangible assets, net $ 3,089 $ 4,461
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	Based on the finite-lived intangible assets recorded as of December 31, 2020, the estimated future amortization expense for the next five years is as follows (in thousands): Year Ending December 31: 2021 $ 532 2022 532 2023 532 2024 260 2025 213 Total $ 2,069

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment Net	Property and equipment, net consists of the following: December 31, 2020 2019 (in thousands) Laboratory equipment $ 16,769 $ 11,986 Computer equipment 556 540 Furniture and fixtures 1,444 1,351 Leasehold improvements 7,274 7,121 Construction in progress 1,135 142 Property and equipment, gross 27,178 21,140 Less accumulated depreciation and amortization (9,232 ) (4,832 ) Total property and equipment, net $ 17,946 $ 16,308
Schedule of Accrued and Other Liabilities	Accrued and other liabilities consist of the following: December 31, 2020 2019 (in thousands) Research and development expenses $ 49,384 $ 12,530 Payroll and related expenses 17,060 9,410 Excess funds payable under grant agreements 3,467 94 Operating lease liabilities, current 3,625 — Restricted stock liability — 1,434 Financing lease obligation, current 265 237 Other professional and consulting expenses 2,595 1,634 Other accrued expenses 540 1,156 Total accrued and other liabilities $ 76,936 $ 26,495

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Summary of Lease Costs and Additional Information Related to Operating Leases	The following table contains a summary of the lease costs recognized under ASC 842 and additional information related to operating leases: Year Ended (in thousands) December 31, 2020 Operating lease cost $ 4,591 Short-term lease cost 459 Variable lease cost 2,299 Total least cost $ 7,349 Other Information Weighted average remaining lease term (in years) 10.6 years Weighted average incremental borrowing rate 7.7 %
Schedule of Maturities of Operating Lease Liabilities	The maturity of the Company’s operating lease liabilities as of December 31, 2020 was as follows (in thousands): Amounts 2021 $ 6,247 2022 9,725 2023 11,399 2024 10,576 2025 8,054 Thereafter 67,503 Total lease payments 113,504 Less: imputed interest (40,949 ) Less: net tenant improvement allowance yet to be received (10,287 ) Present value of operating lease liabilities $ 62,268
Schedule of Operating Lease Amounts Recorded in Condensed Consolidated Balance Sheet	The following amounts were recorded in the consolidated balance sheet as of December 31, 2020 (in thousands): Operating Leases Current operating lease liabilities, net of tenant improvement allowances (1) $ 7,913 Operating ROU assets 61,947 Accrued and other liabilities $ 3,625 Operating lease liabilities, noncurrent 66,556 Total operating lease liabilities $ 70,181 (1) Current portion of lease liabilities recorded in prepaid expenses and other current assets for which the lease incentives to be received exceed the minimum lease payments to be paid over the next twelve months.

Stock-Based Awards (Tables)

Stock-Based Awards (Tables)	12 Months Ended
	Dec. 31, 2020
Summary of Stock Option Plans Activity	Activity under the Company’s stock option plans is set forth below: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (Years) (in thousands) Outstanding at December 31, 2019 7,186,298 $ 5.25 8.5 Granted 4,893,710 $ 32.94 Exercised (1,618,368 ) $ 2.51 Canceled (663,358 ) $ 11.56 Outstanding at December 31, 2020 9,798,282 $ 19.10 8.6 $ 109,272 Vested and expected to vest at December 31, 2020 9,798,282 $ 19.10 8.6 $ 109,272 Vested and exercisable at December 31, 2020 2,462,133 $ 5.40 7.7 $ 52,773
Summary of Restricted Stock Activity	The following table summarizes restricted stock activity: Number of Shares Weighted Average Fair Value at Date of Grant per Share Unvested as of December 31, 2019 2,075,511 $ 0.95 Vested (1,986,250 ) 0.92 Unvested as of December 31, 2020 89,261 $ 1.48
Summary of Stock-based Compensation Expense	The following table sets forth the total stock-based compensation expense for all awards granted to employees and non-employees, including shares sold through the issuance of non-recourse promissory notes of which all the shares are considered to be options for accounting purposes in the Company’s consolidated statements of operations: Year Ended December 31, 2020 2019 2018 (in thousands) Research and development $ 13,663 $ 3,034 $ 1,056 General and administrative 13,937 5,685 3,997 Total stock-based compensation $ 27,600 $ 8,719 $ 5,053
Stock Option
Summary of Assumptions Used for Estimating the Fair Value of Stock Options Granted	The fair value of stock options granted to employees was estimated on the date of grant using the Black-Scholes option pricing model using the following assumptions: Year Ended December 31, 2020 2019 2018 Expected term of options (in years) 5.0 – 6.1 5.9 – 6.1 6.0 Expected stock price volatility 88.8% – 108.6% 86.5% – 89.4% 86.4% – 88.0% Risk-free interest rate 0.3% – 1.2% 1.5% – 2.5% 2.5% – 3.0% Expected dividend yield — — —

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of Potentially Dilutive Securities Not Included in the Diluted Per Share Calculations	Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: As of December 31, 2020 2019 2018 Convertible preferred stock — — 69,910,520 Options issued and outstanding 9,798,282 7,186,298 5,044,924 Restricted shares subject to future vesting 89,261 2,075,511 4,814,733 Warrants to purchase convertible preferred stock — — 244,444 Warrants to purchase common stock — 244,444 — Total 9,887,543 9,506,253 80,014,621

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Loss Before Provision for (Benefit from) Income Taxes	Loss before provision for (benefit from) income taxes consists of the following (in thousands): Year Ended December 31, 2020 2019 2018 Domestic $ (309,697 ) $ (138,724 ) $ (110,399 ) Foreign 11,086 (35,805 ) (5,965 ) Total loss before provision for (benefit from) income taxes $ (298,611 ) $ (174,529 ) $ (116,364 )
Components of Income Tax Expense (Benefit)	The components of income tax expense (benefit) consist of the following (in thousands): Year Ended December 31, 2020 2019 2018 Current: Federal $ — $ — $ — State — — — Foreign 106 154 20 106 154 20 Deferred: Federal (21 ) — (445 ) State (31 ) — (55 ) Foreign — — — (52 ) — (500 ) Provision for (benefit from) income taxes $ 54 $ 154 $ (480 )
Reconciliation Between Expected Income Tax Provision at Federal Statutory Rate and Reported Income Tax Benefit	A reconciliation between the expected income tax provision at the federal statutory rate and the reported income tax benefit is as follows: Year Ended December 31, 2020 2019 2018 U.S. federal statutory income tax rate 21.0 % 21.0 % 21.0 % Foreign tax at less than federal statutory rate 0.9 (0.3 ) (0.1 ) Prior year tax rate adjustment (1.9 ) — — State taxes, net of federal benefit 2.7 2.4 2.0 Research and development tax credit 1.8 2.0 2.2 Acquired IPR&D — — (2.9 ) Permanent items 1.3 (0.8 ) (0.4 ) Changes in valuation allowance - Humabs IP transfer (1.9 ) — — Changes in valuation allowance (23.4 ) (24.3 ) (21.4 ) Other (0.5 ) (0.1 ) — Effective income tax rate 0.0 % (0.1 )% 0.4 %
Schedule of Deferred Tax Assets and Liabilities	The tax effects of temporary differences that give rise to significant portions of the Company’s deferred tax assets and liabilities as of December 31, 2020 and 2019, are related to the following: December 31, 2020 2019 (in thousands) Deferred tax assets: Net operating loss carryforwards $ 117,433 $ 67,493 Research and development tax credit carryforward 12,246 6,978 Equity compensations 4,193 1,514 Reserves and accruals 10,804 6,988 Lease liabilities 16,184 — Intangible assets 23,006 9,733 Deferred tax assets 183,866 92,706 Deferred tax liabilities: ROU assets (16,147 ) — Property and equipment (2,570 ) (1,553 ) IPR&D (8,511 ) (8,647 ) Deferred tax liabilities (27,228 ) (10,200 ) Valuation allowance (159,891 ) (85,811 ) Net deferred tax liabilities $ (3,253 ) $ (3,305 )
Reconciliation of Liability for Uncertain Tax Positions	A reconciliation of the beginning and ending amounts of the liability for uncertain tax positions is as follows: Year Ended December 31, 2020 2019 2018 (in thousands) Gross unrecognized tax benefits at January 1 $ 2,725 $ 2,404 $ 272 Addition for tax positions taken in the prior years — 133 32 Reduction for tax positions taken in the prior years (588 ) (1,596 ) (215 ) Addition for tax positions taken in current year 2,740 1,784 2,315 Gross unrecognized tax benefits at December 31 $ 4,877 $ 2,725 $ 2,404

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Schedule of Selected Quarterly Financial Data	Three Months Ended March 31, 2020 June 30, 2020 September 30, 2020 December 31, 2020 (in thousands) Total revenue $ 5,718 $ 66,988 $ 1,928 $ 1,734 Total operating expenses $ (77,628 ) $ (96,039 ) $ (89,543 ) $ (110,138 ) Net loss $ (77,240 ) $ (31,167 ) $ (84,609 ) $ (105,649 ) Net loss per share, basic $ (0.71 ) $ (0.27 ) $ (0.67 ) $ (0.83 ) Net loss per share, diluted $ (0.71 ) $ (0.27 ) $ (0.67 ) $ (0.83 ) Three Months Ended March 31, 2019 June 30, 2019 September 30, 2019 December 31, 2019 (in thousands) Total revenue $ 3,661 $ 2,047 $ 1,403 $ 980 Total operating expenses $ (34,431 ) $ (37,817 ) $ (49,083 ) $ (64,739 ) Net loss $ (28,670 ) $ (33,928 ) $ (48,314 ) $ (63,771 ) Net loss per share, basic $ (3.19 ) $ (3.64 ) $ (4.60 ) $ (0.69 ) Net loss per share, diluted $ (3.19 ) $ (3.64 ) $ (4.60 ) $ (0.71 )

Organization - Additional Infor

Organization - Additional Information (Details) $ / shares in Units, $ in Thousands	Nov. 30, 2020$ / shares	Jul. 10, 2020USD ($)$ / sharesshares	Oct. 10, 2019USD ($)$ / sharesshares	Sep. 16, 2019	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Oct. 11, 2019shares	Dec. 31, 2018shares	Dec. 31, 2017shares	Sep. 30, 2016shares
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Reverse stock split, conversion ratio				0.222222222
Reverse stock split, description					On September 16, 2019, the Company’s board of directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a 1-for-4.5 reverse split (“Reverse Split”) of shares of the Company’s common and convertible preferred stock, which was effected on September 27, 2019.
Net proceeds after deducting underwriting discounts, commissions and offering expenses | $			$ 126,400
Common stock, par value | $ / shares					$ 0.0001	$ 0.0001
Accumulated deficit | $					$ 667,184	$ 368,519
Cash, cash equivalents and short-term investments | $					$ 736,900
Convertible Preferred Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Outstanding convertible preferred stock (in shares) | shares								69,910,520	65,944,430
Series A-1 Convertible Preferred Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Warrant to purchase of convertible preferred stock | shares										244,444
Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of convertible preferred stock converted to shares of common stock (in shares) | shares						88,112,733
Warrant to purchase of convertible preferred stock | shares			244,444
Common Stock | Sales Agreement
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Issuance of common stock, shares | shares					0
Common stock, par value | $ / shares	$ 0.0001
Common Stock | Sales Agreement | Maximum
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Percentage of aggregate gross proceeds from sale of shares	3.00%
Aggregate offering price | $					$ 300,000
IPO
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Issuance of common stock, shares | shares			7,142,858
Common stock price per share | $ / shares			$ 20
Outstanding convertible preferred stock (in shares) | shares			88,112,733				0
Gross proceeds from the offering | $						$ 126,411
IPO | Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Issuance of common stock, shares | shares						7,142,858
Gross proceeds from the offering | $						$ 1
IPO | Common Stock | Convertible Preferred Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of convertible preferred stock converted to shares of common stock (in shares) | shares			88,112,733
IPO | Common Stock | Warrant to Purchase Convertible Preferred Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of convertible preferred stock converted to shares of common stock (in shares) | shares			244,444
Follow-on Offering
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Gross proceeds from the offering | $					$ 323,214
Follow-on Offering | Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Issuance of common stock, shares | shares		8,214,285			8,214,285
Common stock price per share | $ / shares		$ 42
Gross proceeds from the offering | $		$ 345,000			$ 1
Payments of underwriting discounts and commissions | $		20,700
Offering expenses | $		1,100
Net proceeds after deducting underwriting discounts, commissions and offering expenses | $		$ 323,200

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020USD ($)Segment	Jan. 01, 2020USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segment | Segment	1
Allowance for losses on available-for-sale debt securities	$ 0
Property and equipment, estimated useful lives description	Depreciation and amortization are computed using the straight-line method over the estimated useful lives of the respective assets, generally three to five years.
Indefinite-lived impairment of intangible assets	$ 0
Finite-lived intangible assets, amortization method description	Amortization is computed using the straight-line method over the estimated useful lives of the respective finite-lived intangible assets, generally seven to 15 years.
Operating lease ROU assets	$ 61,947,000
Operating lease liabilities	$ 70,181,000
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life	3 years
Finite-lived intangible asset, estimated useful life	7 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life	5 years
Finite-lived intangible asset, estimated useful life	15 years
ASU 2016-13
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 1, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	false
ASU 2016-02
Summary Of Significant Accounting Policies [Line Items]
Operating lease ROU assets		$ 16,800,000
Operating lease liabilities		$ 17,500,000
ASU 2017-04
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 1, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true
ASU 2018-13
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 1, 2020
ASU 2018-14
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Dec. 31, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true
ASU 2018-18
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 1, 2020
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets Measured at Fair Value on a Recurring Basis by Level Within Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Dec. 31, 2020		Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost	$ 722,036		$ 406,883
Financial Assets, Gross Unrealized Holding Gains	91		140
Financial Assets, Gross Unrealized Holding Losses	(6)		(5)
Financial Assets, Aggregate Fair Value	722,121		407,018
Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost	421,835	[1]	106,127	[2]
Financial Assets, Aggregate Fair Value	421,835	[1]	106,127	[2]
Level 2 | U.S. Government Treasuries
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost	300,201		298,256	[3]
Financial Assets, Gross Unrealized Holding Gains	91		140	[3]
Financial Assets, Gross Unrealized Holding Losses	(6)		(5)	[3]
Financial Assets, Aggregate Fair Value	$ 300,286		298,391	[3]
Level 2 | Bank Time Deposits
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost			2,500
Financial Assets, Aggregate Fair Value			$ 2,500
[1]	Includes $14.9 million of restricted cash equivalents.
[2]	Includes $13.5 million of restricted cash equivalents.
[3]	ncludes $24.3 million classified as long-term investments

Fair Value Measurements - Fin_2

Fair Value Measurements - Financial Assets Measured at Fair Value on a Recurring Basis by Level Within Fair Value Hierarchy (Parenthetical) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Long-term investments		$ 24,290
Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Restricted cash equivalents	$ 14,900	13,500
Long-term investments		$ 24,300

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	Mar. 10, 2020	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total unrealized gains recorded in accumulated other comprehensive income (loss)		$ 100	$ 100
Derivative liability			12,449
Reclassification of derivative liability to additional paid-in capital upon achievement of development milestone	$ 29,200
Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities contractual term		1 year
Humabs
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Specified clinical development milestones payment		$ 20,000
Estimated fair value of contingent consideration		29,200	14,900
TomegaVax
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated fair value of contingent consideration		$ 6,800	$ 2,700

Fair Value Measurements - Estim

Fair Value Measurements - Estimated Fair Value of Significant Unobservable Inputs (Details)	Dec. 31, 2020
Humabs | Clinical and Regulatory Milestones | Measurement Input, Discount Rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.07	[1]
Humabs | Clinical and Regulatory Milestones | Measurement Input, Discount Rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.09	[1]
Humabs | Clinical and Regulatory Milestones | Measurement Input, Discount Rate | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.08	[1]
Humabs | Clinical and Regulatory Milestones | Probability of Achievement | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.14	[1]
Humabs | Clinical and Regulatory Milestones | Probability of Achievement | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.32	[1]
Humabs | Clinical and Regulatory Milestones | Probability of Achievement | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.27	[1]
Humabs | Commercial Milestones | Measurement Input, Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.11	[2]
Humabs | Commercial Milestones | Probability of Achievement | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.14	[2]
Humabs | Commercial Milestones | Probability of Achievement | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.32	[2]
Humabs | Commercial Milestones | Probability of Achievement | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.28	[2]
Humabs | Commercial Milestones | Measurement Input Expected Revenue Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.60	[2]
TomegaVax | Measurement Input, Discount Rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0	[1]
TomegaVax | Measurement Input, Discount Rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.001	[1]
TomegaVax | Measurement Input, Discount Rate | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.001	[1]
TomegaVax | Expected Stock Price Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.85	[1]
[1]	Unobservable inputs were weighted based on the relative fair value of the underlying milestones.
[2]	Unobservable inputs were weighted based on the relative fair value of the commercial milestone payments.

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Changes in Estimated Fair Value of Financial Liabilities (Details) - USD ($) $ in Thousands	Mar. 10, 2020	Dec. 31, 2020
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Reclassification of derivative liability to additional paid-in capital upon achievement of development milestone	$ 29,200
Level 3
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2019		$ 30,029
Changes in fair value		55,190
Payment of contingent consideration related to Humabs acquisition		(20,000)
Reclassification of derivative liability to additional paid-in capital upon achievement of development milestone		(29,245)
Balance at December 31, 2020		35,974
Level 3 | Contingent Consideration
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2019		17,580
Changes in fair value		38,394
Payment of contingent consideration related to Humabs acquisition		(20,000)
Balance at December 31, 2020		35,974
Level 3 | Derivative Liability
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2019		12,449
Changes in fair value		16,796
Reclassification of derivative liability to additional paid-in capital upon achievement of development milestone		$ (29,245)

Acquisitions - Additional Infor

Acquisitions - Additional Information (Details)	1 Months Ended							12 Months Ended
	Feb. 28, 2021USD ($)	Oct. 31, 2020USD ($)	Jun. 30, 2020USD ($)	May 31, 2020Milestone	Jan. 31, 2018USD ($)shares	Aug. 31, 2017USD ($)shares	Sep. 30, 2016USD ($)	Dec. 31, 2020USD ($)Milestone	Dec. 31, 2018USD ($)	Dec. 31, 2019USD ($)
TomegaVax
Business Acquisition [Line Items]
Business acquisition purchase price							$ 5,200,000
Business acquisition, transaction costs							500,000
TomegaVax | TomegaVax Letter Agreement
Business Acquisition [Line Items]
Milestone payments aggregate amount payable, maximum							$ 30,000,000
Milestone payments related terms								the Company will be required to pay to the former stockholders of TomegaVax milestone payments of up to an aggregate of $30.0 million if the per-share price of the Company’s publicly traded common stock, or implied price per-share of the Company’s Series A-1 convertible preferred stock (or common stock upon conversion) upon a certain asset sale, merger or stock sale, is at least $45 (as adjusted in the case of any stock dividend, stock split or other similar recapitalization), with the amount of such payments determined by the share price and the stage of the Company’s clinical development at the time of the relevant event triggering the payment.
TomegaVax | TomegaVax Letter Agreement | Contingent Consideration Liability
Business Acquisition [Line Items]
Fair value of embedded derivative								$ 6,800,000
TomegaVax | TomegaVax Letter Agreement | Contingent Consideration Liability | Subsequent Event
Business Acquisition [Line Items]
Contingent consideration recognized	$ 10,000,000
Milestone payments, amount payable term	90 days
Humabs
Business Acquisition [Line Items]
Contingent consideration recognized								29,200,000		$ 14,900,000
Business acquisition, cash consideration paid						$ 30,000,000
Business acquisition, shares issued | shares						1,666,656
Business acquisition, shares issued value						$ 2,500,000
Specified clinical development milestones payment								20,000,000
Impairment of intangible assets, excluding goodwill								0
Goodwill expected to be deductible for income tax purposes								$ 0
Humabs | Developed Technologies | Minimum [Member]
Business Acquisition [Line Items]
Estimated remaining useful lives								7 years
Humabs | Developed Technologies | Maximum
Business Acquisition [Line Items]
Estimated remaining useful lives								12 years
Humabs | HBV product
Business Acquisition [Line Items]
Contingent consideration recognized								$ 29,200,000
Additional consideration payable upon achievement of specified milestone events						135,000,000
Number of specified clinical milestones achieved | Milestone				1
Specified clinical development milestones payment			$ 10,000,000
Humabs | Another Product
Business Acquisition [Line Items]
Additional consideration payable upon achievement of specified milestone events						$ 105,000,000
Humabs | SARS-CoV-2 Product
Business Acquisition [Line Items]
Specified clinical development milestones payment		$ 10,000,000
Agenovir
Business Acquisition [Line Items]
Business acquisition purchase price									$ 15,300,000
Business acquisition, transaction costs					$ 700,000
Contingent consideration recognized								$ 0
Business acquisition, cash consideration paid					11,500,000
Business acquisition, liabilities					$ 1,300,000
Number of milestones achieved | Milestone								0
Agenovir | Property and Equipment
Business Acquisition [Line Items]
Business acquisitions, purchase price allocation									800,000
Agenovir | Series A-2 Convertible Preferred Stock
Business Acquisition [Line Items]
Business acquisition, shares issued | shares					555,537
Business acquisition, shares issued value					$ 1,800,000
Agenovir | In-Process Research and Development
Business Acquisition [Line Items]
Business acquisitions, purchase price allocation									$ 14,500,000
Agenovir | HBV product
Business Acquisition [Line Items]
Milestone payments aggregate amount payable, maximum					$ 135,000,000

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Goodwill and Intangible Assets [Line Items]
Goodwill	$ 16,937,000		$ 16,937,000	$ 16,937,000
Goodwill impairment loss			0
Amortization expense of intangible assets			1,042,000	1,223,000	$ 1,138,000
Finite lived intangible assets, impairment charges			832,000
Indefinite-lived impairment of intangible assets			0
Finite-lived intangible asset, reclassified from indefinite-lived asset	$ 500,000
Humabs
Schedule of Goodwill and Intangible Assets [Line Items]
Indefinite-lived intangible assets IPR&D			30,700,000	31,200,000
Indefinite-lived impairment of intangible assets			0	0
Research and Development Expenses
Schedule of Goodwill and Intangible Assets [Line Items]
Amortization expense of intangible assets			$ 1,000,000	$ 1,200,000	$ 1,100,000
Finite lived intangible assets, impairment charges		$ 800,000

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Schedule of Finite Lived Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Finite Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 7,502	$ 7,000
Less accumulated amortization	(3,581)	(2,539)
Less impairment of intangible assets	(832)
Finite-lived intangible assets, net	3,089	4,461
Developed Technology
Finite Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 7,000	$ 7,000
Weighted-Average Remaining Useful Life (Years)	6 years 7 months 6 days
Contract-Based Intangible Asset
Finite Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 502
Weighted-Average Remaining Useful Life (Years)	14 years 10 months 24 days

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Schedule of Estimated Future Amortization Expense (Details) $ in Thousands	Dec. 31, 2020USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
2021	$ 532
2022	532
2023	532
2024	260
2025	213
Total	$ 2,069

Grant Agreements - Additional I

Grant Agreements - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Aug. 31, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2021	Mar. 16, 2018	Jan. 26, 2018
Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants		$ 9,123,000	$ 7,380,000	$ 9,800,000
Bill & Melinda Gates Foundation | Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants		0	900,000	2,000,000
National Institutes of Health
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount		5,100,000
National Institutes of Health | Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants		600,000	900,000	1,100,000
2017 Grant | Bill & Melinda Gates Foundation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant agreement expiration date	May 31, 2019
2017 Grant | Bill & Melinda Gates Foundation | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount	$ 4,700,000
Human Immunodeficiency Virus ("HIV") Grant | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount							$ 12,200,000
Human Immunodeficiency Virus ("HIV") Grant | Bill & Melinda Gates Foundation | Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants		6,400,000	3,700,000	4,400,000
Milestone payment due to Vir		1,900,000
Human Immunodeficiency Virus ("HIV") Grant | Bill & Melinda Gates Foundation | Grant Revenue [Member] | Subsequent Event [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payment received					$ 1,900,000
Tuberculosis ("TB") Grant
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Funds received in advance		3,500,000
Tuberculosis ("TB") Grant | Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants		$ 2,200,000	$ 1,900,000	$ 2,300,000
Tuberculosis ("TB") Grant | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount						$ 14,900,000

Collaboration and License Agr_2

Collaboration and License Agreements - Additional Information (Details) - USD ($)

Apr. 29, 2020

Jun. 30, 2020

Apr. 30, 2020

Sep. 30, 2019

Aug. 31, 2019

Sep. 30, 2018

Jul. 31, 2018

May 31, 2018

Oct. 31, 2017

Jun. 30, 2020

Mar. 31, 2020

Sep. 30, 2019

Jun. 30, 2020

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Mar. 10, 2020

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Termination description

the WuXi Biologics Collaboration Agreement may be terminated by (i) the written agreement of both parties, (ii) WuXi Biologics following the one year anniversary of the WuXi Biologics Collaboration Agreement effective date with respect to the entire agreement or on a product by product basis with 90 days’ prior written notice or (iii) by either party if the other party materially breaches the WuXi Biologics Collaboration Agreement and fails to cure such breach within sixty days.

License

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Total revenue

$ 22,747,000

2020 Stock Purchase Agreement | GGL

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Issuance of common stock, shares

6,626,027

Share purchase price per share

$ 37.73

Issuance of common stock, value

$ 250,000,000

Preliminary Collaboration Agreement | GSK

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Number of years conduct certain research and development activities under mutually agreed development plans

4 years

Maximum percentage of right to perform details in connection with antibody product

20.00%

Termination description

Either party has the right to terminate the GSK Agreement in the case of the insolvency of the other party, an uncured material breach of the other party with respect to a collaboration program or collaboration product, or as mutually agreed by the parties.

Research and development expense

$ 25,400,000

Preliminary Collaboration Agreement | GSK | Accrued Liabilities And Other Liabilities

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Payable

$ 28,000,000

Preliminary Collaboration Agreement | Antibody Program | GSK

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Percentage of development costs

72.50%

Preliminary Collaboration Agreement | Vaccine Program | GSK

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Percentage of development costs

27.50%

Preliminary Collaboration Agreement and 2020 Stock Purchase Agreement | GSK

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Premium paid on sale price of common stock

$ 43,300,000

Total revenue

$ 43,300,000

Preliminary Collaboration Agreement and 2020 Stock Purchase Agreement | GGL | ASC 606

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Fair market value of the common stock issued

$ 206,700,000

Common stock price per share

$ 36.70

Premium paid on sale price of common stock

$ 43,300,000

Brii Agreement

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Termination description

Each party may terminate for convenience all rights and obligations with respect to any program for which it has an option, with 30 days’ written notice (if the terminating party has not exercised an option for such program) or 180 days’ notice (following the exercise of an option for such program). The Brii Agreement may also be terminated by either party for insolvency of the other party, and either party may terminate the Brii Agreement in its entirety or on a program-by-program basis for the other party’s uncured material breach on 60 days’ written notice (or 30 days’ notice following failure to make payment).

Written notice period for not exercising an option

30 days

Written notice period for exercise an option

180 days

Written notice period for uncured material breach

60 days

Written notice period for failure to make payment

30 days

Brii Agreement | Brii Bio Parent

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Percentage of ordinary share equal to outstanding share

9.90%

Option exercise fee ranging from mid-single-digit

$ 20,000,000

20,000,000

$ 20,000,000

Sales milestone receivable

175,000,000

175,000,000

175,000,000

Estimated fair value of investments

$ 6,600,000

Contract liability

2,700,000

2,700,000

2,700,000

Option exercise fee received

20,000,000

Determined transaction price

22,700,000

Milestone payments paid.

10,000,000

Brii Agreement | Brii Bio

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Royalty payment obligation expiration period after first commercial sales

10 years

Contract liability

6,600,000

Brii Agreement | Brii Bio | Maximum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Option exercise fee ranging from mid-single-digit

20,000,000

Option exercise fee of ranging from low tens

50,000,000

Brii Agreement | Brii Bio | China Territory | Maximum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Sales milestone receivable

175,000,000

Brii Agreement | Brii Bio | United States | Maximum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Sale milestone payments

175,000,000

Brii Agreement | Brii Bio | Other Assets

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Carrying value of investment

$ 5,700,000

$ 6,600,000

Brii Agreement | Alnylam Pharmaceuticals Inc | Research and Development Expenses

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Proceeds from options exercised

10,000,000

Brii Agreement | Licensed Product-By-Licensed Product | Brii Bio Parent

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Milestone payment on basis ranging from mid-single-digit

$ 30,000,000

30,000,000

$ 30,000,000

Brii Agreement | Licensed Product-By-Licensed Product | Brii Bio | Maximum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Milestone payment on basis ranging from mid-single-digit

30,000,000

Milestone payment on basis of ranging from low tens

$ 100,000,000

Brii Agreement | License | Brii Bio Parent

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Total revenue

22,700,000

Alnylam Agreement | Alnylam Pharmaceuticals Inc

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Issuance of common stock, shares

1,111,111

Termination description

The Company may terminate the Alnylam Agreement on a program-by-program basis or in its entirety for any reason on 90 days’ written notice. Either party may terminate the agreement for cause for the other party’s uncured material breach on 60 days’ written notice (or 30 days’ notice for payment breach), or if the other party challenges the validity or enforceability of any patent licensed to it under the Alnylam Agreement on 30 days’ notice

Royalty payment obligation expiration period after first commercial sales

10 years

Written notice period for exercise an option

90 days

Written notice period for uncured material breach

60 days

Written notice period for failure to make payment

30 days

Upfront fee paid

$ 10,000,000

Recognized liability

800,000

Maximum shares to be issued

1,111,111

Written notice period for licensed program other party challenges validity or enforceability of patent license.

30 days

Embedded derivative liability

$ 0

$ 0

13,600,000

Estimated fair value of the derivative liability

12,400,000

$ 29,200,000

Contractual payments

$ 15,000,000

Milestone payments paid.

$ 15,000,000

Expenses incurred under agreement

$ 11,500,000

18,100,000

$ 8,300,000

Alnylam Agreement | First siRNA Product | Alnylam Pharmaceuticals Inc

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Maximum milestone payment for achievement of specified development and regulatory

$ 190,000,000

Alnylam Agreement | Each Infectious Disease siRNA | Alnylam Pharmaceuticals Inc

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Maximum milestone payment for achievement of specified development and regulatory

115,000,000

Alnylam Agreement | Commercialization | Alnylam Pharmaceuticals Inc

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Maximum aggregate sales milestone payment

250,000,000

Maximum sales milestone payment

$ 100,000,000

Rockefeller Agreement | Rockefeller

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Termination description

The Company has the right to terminate the Rockefeller Agreement in its entirety, or in part, for any reason on 60 days’ written notice to Rockefeller. Rockefeller may terminate the Rockefeller Agreement on 90 days’ written notice for the Company’s uncured material breach, or if the Company challenges the validity or enforceability of any of the licensed patents, or immediately in the event of the Company’s insolvency. Rockefeller may also terminate the Rockefeller Agreement if the Company ceases to carry on business with respect to the rights granted to the Company under the agreement.

Upfront fee paid

$ 300,000

Payment of annual license maintenance fees

1,000,000

Maximum aggregate milestone payment for achievement of specified development and regulatory

$ 40,000,000

Royalty obligation period from date of first commercial sale

12 years

Rockefeller Agreement | First Infectious Disease Product | Rockefeller

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Maximum milestone payment for achievement of specified development and regulatory

$ 8,500,000

Rockefeller Agreement | First Four Other Infectious Disease Products | Rockefeller

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Maximum sales milestone payment

7,000,000

Rockefeller Agreement | Any Other Infectious Disease Product | Rockefeller

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Maximum sales milestone payment

$ 3,600,000

Rockefeller Agreement | HBV Program | Rockefeller | Research and Development Expenses

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Specified development milestones and annual license maintenance fees

$ 1,300,000

License maintenance fees

$ 1,000,000

MedImmune Agreement | MedImmune

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Termination description

The Company may terminate the MedImmune Agreement in its entirety or on a product-by-product basis, for convenience, upon 120 days’ notice. Either party may terminate the MedImmune Agreement for cause for the other party’s uncured material breach on 60 days’ notice or immediately in the event of bankruptcy of the other party. Additionally, MedImmune may terminate the MedImmune Agreement for cause on 30 days’ written notice if the Company challenges the validity or enforceability of the patents to which the Company has obtained a license under the MedImmune Agreement.

License agreement upfront payment

$ 10,000,000

MedImmune Agreement | Influenza A and Influenza B | MedImmune

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Development, regulatory, and commercial milestone payments maximum amount

$ 331,500,000

MedImmune Agreement | Influenza A | MedImmune

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Specified development milestones payment

$ 5,000,000

2019 Xencor Agreement | Xencor

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Termination description

The Company may terminate each agreement in its entirety, or on a target-by-target basis, for convenience upon 60 days’ written notice. Either party may terminate each agreement for the other party’s uncured material breach upon 60 days’ written notice (or 30 days in the case of non-payment) or in the event of bankruptcy of the other party immediately upon written notice. Xencor may terminate each agreement immediately upon written notice if the Company challenges, or upon 30 days’ written notice if any of the Company’s sublicensees challenge, the validity or enforceability of any patent licensed to the Company under each respective agreement.

Written notice period for uncured material breach

60 days

Written notice period for failure to make payment

30 days

Written notice period for termination of licensed program

60 days

Written notice period for termination of licensed program based on challenge

30 days

2019 Xencor Agreement | Influenza A Research Programs | Xencor

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Specified development milestones payment

$ 800,000

Maximum aggregate development and regulatory milestone payments

$ 17,800,000

Maximum aggregate commercial sales milestone payments

60,000,000

Maximum aggregate milestone payments

77,800,000

2019 Xencor Agreement | HBV Research Programs | Xencor

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Specified development milestones payment

$ 300,000

Maximum aggregate milestone payments

77,800,000

2019 Xencor Agreement | Influenza A and HBV Research Programs | Xencor

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Maximum aggregate milestone payments

$ 155,500,000

2020 Xencor Agreement | Xencor

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Termination description

The Company may terminate each agreement in its entirety, or on a target-by-target basis, for convenience upon 60 days’ written notice. Either party may terminate each agreement for the other party’s uncured material breach upon 60 days’ written notice (or 30 days in the case of non-payment) or in the event of bankruptcy of the other party immediately upon written notice. Xencor may terminate each agreement immediately upon written notice if the Company challenges, or upon 30 days’ written notice if any of the Company’s sublicensees challenge, the validity or enforceability of any patent licensed to the Company under each respective agreement.

Written notice period for uncured material breach

60 days

Written notice period for failure to make payment

30 days

Licensed patents expiration period

12 years

Written notice period for termination of licensed program

60 days

Written notice period for termination of licensed program based on challenge

30 days

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Property and Equipment Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 27,178	$ 21,140
Less accumulated depreciation and amortization	(9,232)	(4,832)
Total property and equipment, net	17,946	16,308
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	16,769	11,986
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	556	540
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,444	1,351
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	7,274	7,121
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 1,135	$ 142

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Aug. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization expenses		$ 4,400	$ 3,294	$ 1,618
Proceeds from sale leaseback of financing obligation	$ 1,200
Lease, term of contract	5 years
Current portion of finance lease obligation		265	$ 237
Long-term portion of finance lease obligation		$ 700

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Accrued and Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Research and development expenses	$ 49,384	$ 12,530
Payroll and related expenses	17,060	9,410
Excess funds payable under grant agreements	3,467	94
Operating lease liabilities, current	3,625
Restricted stock liability		1,434
Financing lease obligation, current	265	237
Other professional and consulting expenses	2,595	1,634
Other accrued expenses	540	1,156
Total accrued and other liabilities	$ 76,936	$ 26,495

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	Aug. 04, 2020	Jun. 15, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Apr. 09, 2020
Loss Contingencies [Line Items]
Lease arrangement, contractual expiration period, beginning year			2021
Lease arrangement, contractual expiration period, ending year			2033
Lessee, operating lease, existence of option to extend [true false]			true
Lessee, operating lease, option to extend			These leases require monthly lease payments that may be subject to annual increases throughout the lease term. Certain lease agreements also provide the Company with the option to renew for additional periods ranging from three months to five years.
Tenant improvement allowance			$ 10.5
Cash paid for operating lease liabilities			5.1
ROU assets in exchange for operating lease liabilities			$ 48.5
Rent expense				$ 4.4	$ 4
Samsung Biologics Co., Ltd
Loss Contingencies [Line Items]
Obligated to pay capacity reservation						$ 362
WuXi Biologics
Loss Contingencies [Line Items]
Obligated to pay capacity reservation		$ 130
GSKTSL | WuXi Biologics MSA and Samsung MSA | Antibody Program
Loss Contingencies [Line Items]
Percentage of development costs	72.50%
GSK | WuXi Biologics MSA and Samsung MSA | Antibody Program
Loss Contingencies [Line Items]
Percentage of development costs	27.50%
Minimum [Member]
Loss Contingencies [Line Items]
Lessee, operating lease, renewal term			3 months
Minimum [Member] | WuXi Biologics
Loss Contingencies [Line Items]
Percentage of estimated raw material costs		70.00%
Maximum
Loss Contingencies [Line Items]
Lessee, operating lease, renewal term			5 years
Maximum | WuXi Biologics
Loss Contingencies [Line Items]
Percentage of estimated raw material costs		80.00%

Commitments and Contingencies_2

Commitments and Contingencies - Summary of Lease Costs and Additional Information Related to Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)
Commitments And Contingencies Disclosure [Abstract]
Operating lease cost	$ 4,591
Short-term lease cost	459
Variable lease cost	2,299
Total least cost	$ 7,349
Other Information
Weighted average remaining lease term (in years)	10 years 7 months 6 days
Weighted average incremental borrowing rate	7.70%

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Maturities of Operating Lease Liabilities (Details) $ in Thousands	Dec. 31, 2020USD ($)
Commitments And Contingencies Disclosure [Abstract]
2021	$ 6,247
2022	9,725
2023	11,399
2024	10,576
2025	8,054
Thereafter	67,503
Total lease payments	113,504
Less: imputed interest	(40,949)
Less: net tenant improvement allowance yet to be received	(10,287)
Present value of operating lease liabilities	$ 62,268

Commitments and Contingencies_4

Commitments and Contingencies - Schedule of Operating Lease Amounts Recorded in Condensed Consolidated Balance Sheet (Details) $ in Thousands	Dec. 31, 2020USD ($)
Operating Leases
Current operating lease liabilities, net of tenant improvement allowances	$ 7,913	[1]
Operating ROU assets	61,947
Operating lease liabilities, current	$ 3,625
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesAndOtherLiabilities
Operating lease liabilities, noncurrent	$ 66,556
Total operating lease liabilities	$ 70,181
[1]	Current portion of lease liabilities recorded in prepaid expenses and other current assets for which the lease incentives to be received exceed the minimum lease payments to be paid over the next twelve months.

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details)	Jan. 31, 2019shares
Series B Convertible Preferred Stock
Related Party Transaction [Line Items]
Preferred stock shares issued	18,202,213

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Oct. 10, 2019	Aug. 31, 2019	Jan. 31, 2019	Jul. 31, 2018	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Oct. 11, 2019	Dec. 31, 2017
Temporary Equity [Line Items]
Gross proceeds from sale of convertible preferred stock						$ 317,335	$ 14,254
Common Stock
Temporary Equity [Line Items]
Conversion of convertible preferred stock into common stock (in shares)						88,112,733
IPO
Temporary Equity [Line Items]
Convertible preferred stock, shares outstanding	88,112,733							0
Series A-1 Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares sold					3,222,220		3,222,220
Convertible preferred stock, shares sold, price per share					$ 4.50
Gross proceeds from sale of convertible preferred stock					$ 14,500
Convertible preferred stock, additional shares authorized					1,111,121
Series A-1 Convertible Preferred Stock | Two Closings
Temporary Equity [Line Items]
Convertible preferred stock, shares sold					2,777,776
Series A-1 Convertible Preferred Stock | Third Closing
Temporary Equity [Line Items]
Convertible preferred stock, shares sold				444,444
Series B Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares sold		18,202,213				18,202,213
Convertible preferred stock, shares sold, price per share			$ 18
Gross proceeds from sale of convertible preferred stock			$ 327,500
Convertible preferred stock, additional shares authorized			4,020,009
Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares outstanding							69,910,520		65,944,430
Convertible Preferred Stock | IPO | Common Stock
Temporary Equity [Line Items]
Conversion of convertible preferred stock into common stock (in shares)	88,112,733

Convertible Preferred Stock W_2

Convertible Preferred Stock Warrant Liability - Additional Information (Details) - $ / shares	1 Months Ended
	Sep. 30, 2016	Oct. 10, 2019
Class Of Warrant Or Right [Line Items]
Warrant, expiration date	Sep. 11, 2026
Series A-1 Convertible Preferred Stock
Class Of Warrant Or Right [Line Items]
Warrant to purchase of convertible preferred stock	244,444
Warrants issued, exercise price	$ 4.50
Warrant
Class Of Warrant Or Right [Line Items]
Common stock shares issued for conversion of warrants	211,774
Common Stock
Class Of Warrant Or Right [Line Items]
Warrant to purchase of convertible preferred stock		244,444

Stock-Based Awards - Additional

Stock-Based Awards - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended				12 Months Ended
	Sep. 30, 2019	Aug. 31, 2019	Jan. 31, 2017	Sep. 30, 2016	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted Stock Purchase Agreement | Executive Officer and Director
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase of restricted stock			3,624,355
Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate intrinsic value of options exercised					$ 53.1	$ 5.5
Weighted average grant date fair value of options granted					$ 25.49	$ 7.83	$ 1.72
Unamortized stock-based compensation expense related to stock option					$ 117.5
Estimated weighted average period					2 years 8 months 12 days
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Estimated weighted average period					4 months 24 days
Repayment of outstanding promissory notes and accrued interest received		$ 3.3
Unrecognized compensation cost related to unvested restricted stock					$ 0.1
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase of restricted stock					1,986,250	1,348,297	2,247,673
2016 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period				4 years
2016 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration period of awards from issuance date				10 years
Percentage of estimated fair value of options on the date of grant				100.00%
2019 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting period	4 years
Shares available for grant					6,122,335
2019 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration period of awards from issuance date	10 years
Percentage of estimated fair value of options on the date of grant	100.00%
2019 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum term of offering period specified under plan	27 months
Share issued under plan					0
2019 Employee Stock Purchase Plan | Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares authorized to issue under purchase rights granted	1,280,000
Percentage of employee payroll deduction on earnings	15.00%
Purchase price as percentage of lower of fair market value on offering date	85.00%
Purchase price as percentage of lower of fair market value on purchase date	85.00%

Stock-Based Awards - Summary of

Stock-Based Awards - Summary of Stock Option Plans Activity (Details) - Stock Option - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options,Outstanding, Beginning Balance	7,186,298
Number of Options,Granted	4,893,710
Number of Options,Exercised	(1,618,368)
Number of Options,Canceled	(663,358)
Number of Options,Outstanding, Ending Balance	9,798,282	7,186,298
Number of Options,Vested and expected to vest	9,798,282
Number of Options,Vested and exercisable	2,462,133
Weighted Average Exercise Price, Beginning Balance	$ 5.25
Weighted Average Exercise Price, Granted	32.94
Weighted Average Exercise Price, Exercised	2.51
Weighted Average Exercise Price, Canceled	11.56
Weighted Average Exercise Price, Ending Balance	19.10	$ 5.25
Weighted Average Exercise Price,Vested and expected to vest	19.10
Weighted Average Exercise Price,Vested and exercisable	$ 5.40
Weighted Average Remaining Contractual Term	8 years 7 months 6 days	8 years 6 months
Weighted Average Remaining Contractual Term,Vested and expected to vest	8 years 7 months 6 days
Weighted Average Remaining Contractual Term,Vested and exercisable	7 years 8 months 12 days
Aggregate Intrinsic Value, Balance	$ 109,272
Aggregate Intrinsic Value, Vested and expected to vest	109,272
Aggregate Intrinsic Value, Vested and exercisable	$ 52,773

Stock-Based Awards - Summary _2

Stock-Based Awards - Summary of Assumptions Used for Estimating the Fair Value of Stock Options Granted (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term of options (in years)			6 years
Expected stock price volatility,minimum	88.80%	86.50%	86.40%
Expected stock price volatility,maximum	108.60%	89.40%	88.00%
Risk-free interest rate, minimum	0.30%	1.50%	2.50%
Risk-free interest rate, maximum	1.20%	2.50%	3.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term of options (in years)	5 years	5 years 10 months 24 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term of options (in years)	6 years 1 month 6 days	6 years 1 month 6 days

Stock-Based Awards - Summary _3

Stock-Based Awards - Summary of Restricted Stock Activity (Details) - Restricted Stock	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Unvested, Beginning Balance | shares	2,075,511
Number of Shares, Vested | shares	(1,986,250)
Number of Shares, Unvested, Ending Balance | shares	89,261
Weighted Average Fair Value at Date of Grant Per Share, Beginning Balance | $ / shares	$ 0.95
Weighted Average Fair Value at Date of Grant Per Share, Vested | $ / shares	0.92
Weighted Average Fair Value at Date of Grant Per Share, Ending Balance | $ / shares	$ 1.48

Stock-Based Awards - Summary _4

Stock-Based Awards - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 27,600	$ 8,719	$ 5,053
Research and Development Expenses
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	13,663	3,034	1,056
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 13,937	$ 5,685	$ 3,997

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Potentially Dilutive Securities Not Included in Diluted Per Share Calculations (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)	9,887,543	9,506,253	80,014,621
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)			69,910,520
Options Issued and Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)	9,798,282	7,186,298	5,044,924
Restricted Shares Subject to Future Vesting
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)	89,261	2,075,511	4,814,733
Warrants to Purchase Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)			244,444
Warrants to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)		244,444

Defined Benefit Pension and O_2

Defined Benefit Pension and Other Postretirement Plans - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, contribution expenses	$ 1.8	$ 1.2	$ 0.7
Humabs
Defined Benefit Plan Disclosure [Line Items]
Net liability recognized under pension plans	$ 2.9	$ 1.9
Pension Plan | First Plan | Humabs
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, company contribution	65.00%
Defined contribution plan, employee contribution	35.00%
Pension Plan | Second Plan | Humabs
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, company contribution	60.00%
Defined contribution plan, employee contribution	40.00%

Income Taxes - Schedule of Loss

Income Taxes - Schedule of Loss Before Provision for (Benefit from) Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic	$ (309,697)	$ (138,724)	$ (110,399)
Foreign	11,086	(35,805)	(5,965)
Loss before (provision for) benefit from income taxes	$ (298,611)	$ (174,529)	$ (116,364)

Income Taxes - Components of In

Income Taxes - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Foreign	$ 106	$ 154	$ 20
Current income tax expense (benefit)	106	154	20
Deferred:
Federal	(21)		(445)
State	(31)		(55)
Deferred income tax expense (benefit)	(52)		(500)
Provision for (benefit from) income taxes	$ 54	$ 154	$ (480)

Income Taxes - Reconciliation B

Income Taxes - Reconciliation Between Expected Income Tax Provision at Federal Statutory Rate and Reported Income Tax Benefit (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation Of Effective Income Tax Rate [Line Items]
U.S. federal statutory income tax rate	21.00%	21.00%	21.00%
Foreign tax at less than federal statutory rate	0.90%	(0.30%)	(0.10%)
Prior year tax rate adjustment	(1.90%)
State taxes, net of federal benefit	2.70%	2.40%	2.00%
Research and development tax credit	1.80%	2.00%	2.20%
Acquired IPR&D			(2.90%)
Permanent items	1.30%	(0.80%)	(0.40%)
Changes in valuation allowance	(23.40%)	(24.30%)	(21.40%)
Other	(0.50%)	(0.10%)
Effective income tax rate	0.00%	(0.10%)	0.40%
Humabs IP Transfer
Reconciliation Of Effective Income Tax Rate [Line Items]
Changes in valuation allowance	(1.90%)

Income Taxes - Schedule of Defe

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 117,433	$ 67,493
Research and development tax credit carryforward	12,246	6,978
Equity compensations	4,193	1,514
Reserves and accruals	10,804	6,988
Lease liabilities	16,184
Intangible assets	23,006	9,733
Deferred tax assets	183,866	92,706
Deferred tax liabilities:
ROU assets	(16,147)
Property and equipment	(2,570)	(1,553)
IPR&D	(8,511)	(8,647)
Deferred tax liabilities	(27,228)	(10,200)
Valuation allowance	(159,891)	(85,811)
Net deferred tax liabilities	$ (3,253)	$ (3,305)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Increase in valuation allowance	$ 74,100,000	$ 42,300,000	$ 26,000,000
Unrecognized tax benefit	4,877,000	2,725,000	2,404,000	$ 272,000
Unrecognized tax benefits, if recognized, would reduce effective tax rate	0
Interest and penalties expense related to uncertain tax positions	0	$ 0	$ 0
Interest and penalties accrued related to uncertain tax positions	0
Federal
Income Taxes [Line Items]
Net operating loss carryforwards	$ 483,700,000
Net operating loss carryforwards expiration beginning year	2035
Net operating loss deduction limitation as percentage of taxable income	80.00%
Federal | Research Tax Credit Carryforward
Income Taxes [Line Items]
Tax credit carryforwards	$ 9,100,000
Tax credit carryforwards expiration beginning year	2036
State
Income Taxes [Line Items]
Net operating loss carryforwards	$ 216,800,000
Net operating loss carryforwards expiration beginning year	2031
State | Research Tax Credit Carryforward
Income Taxes [Line Items]
Tax credit carryforwards	$ 7,000,000
State | Oregon | Research Tax Credit Carryforward
Income Taxes [Line Items]
Tax credit carryforwards expiration beginning year	2021
Foreign | Swiss Federal Tax Administration (FTA)
Income Taxes [Line Items]
Net operating loss carryforwards	$ 17,800,000
Net operating loss carryforwards expiration beginning year	2022
Foreign | Australian Taxation Office
Income Taxes [Line Items]
Net operating loss carryforwards	$ 0

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Liability for Uncertain Tax Positions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits at January 1	$ 2,725	$ 2,404	$ 272
Addition for tax positions taken in the prior years		133	32
Reduction for tax positions taken in the prior years	(588)	(1,596)	(215)
Addition for tax positions taken in current year	2,740	1,784	2,315
Gross unrecognized tax benefits at December 31	$ 4,877	$ 2,725	$ 2,404

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) - Schedule of Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 1,734	$ 1,928	$ 66,988	$ 5,718	$ 980	$ 1,403	$ 2,047	$ 3,661	$ 76,368	$ 8,091	$ 10,668
Total operating expenses	(110,138)	(89,543)	(96,039)	(77,628)	(64,739)	(49,083)	(37,817)	(34,431)	(373,348)	(186,070)	(129,360)
Net loss	$ (105,649)	$ (84,609)	$ (31,167)	$ (77,240)	$ (63,771)	$ (48,314)	$ (33,928)	$ (28,670)	$ (298,665)	$ (174,683)	$ (115,884)
Net loss per share, basic	$ (0.83)	$ (0.67)	$ (0.27)	$ (0.71)	$ (0.69)	$ (4.60)	$ (3.64)	$ (3.19)
Net loss per share, diluted	$ (0.83)	$ (0.67)	$ (0.27)	$ (0.71)	$ (0.71)	$ (4.60)	$ (3.64)	$ (3.19)

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ in Millions	Feb. 14, 2021	Apr. 29, 2020	Feb. 28, 2021
Preliminary Collaboration Agreement | GSK
Subsequent Event [Line Items]
Number of years conduct certain research and development activities under mutually agreed development plans		4 years
Subsequent Event | Preliminary Collaboration Agreement | GSK
Subsequent Event [Line Items]
Number of years conduct certain research and development activities under mutually agreed development plans	3 years
Upfront payment receivable	$ 225
Percentage of upfront payment receivable at effective date of agreement	50.00%
Subsequent Event | Definitive Collaboration Agreement | GSK
Subsequent Event [Line Items]
Percentage of upfront payment receivable at effective date of agreement	50.00%
Subsequent Event | 2021 Stock Purchase Agreement | GGL
Subsequent Event [Line Items]
Common stock to be issued, value	$ 120
Subsequent Event | TomegaVax Letter Agreement | TomegaVax | Contingent Consideration Liability
Subsequent Event [Line Items]
Contingent consideration recognized			$ 10
Milestone payments, amount payable term			90 days