Vir Biotechnology (VIR) 10-Q 6 May 21 2021 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	May 03, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Trading Symbol	VIR
Title of 12(b) Security	Common stock, par value $0.0001 per share
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		130,039,838
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-39083
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

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 521,396	$ 436,575
Short-term investments	211,636	300,286
Restricted cash and cash equivalents, current	8,601	7,993
Receivable from collaboration	112,500
Contract asset	112,500
Prepaid expenses and other current assets	26,481	27,511
Total current assets	993,114	772,365
Intangible assets, net	33,687	33,820
Goodwill	16,937	16,937
Property and equipment, net	17,291	17,946
Operating right-of-use assets	60,461	61,947
Restricted cash and cash equivalents, noncurrent	6,998	6,919
Other assets	7,096	8,827
TOTAL ASSETS	1,135,584	918,761
CURRENT LIABILITIES:
Accounts payable	3,701	5,077
Accrued and other liabilities	70,069	76,936
Deferred revenue, current portion	262,929	6,451
Contingent consideration, current portion	24,400	10,600
Total current liabilities	361,099	99,064
Deferred revenue, noncurrent	3,815	3,815
Operating lease liabilities, noncurrent	66,615	66,556
Contingent consideration, noncurrent	46,036	25,374
Deferred tax liability	3,253	3,253
Other long-term liabilities	3,815	3,847
TOTAL LIABILITIES	484,633	201,909
Commitments and contingencies (Note 8)
STOCKHOLDERS’ EQUITY:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized as of March 31, 2021 and December 31, 2020; no shares issued and outstanding as of March 31, 2021 and December 31, 2020
Common stock, $0.0001 par value; 300,000,000 shares authorized as of March 31, 2021 and December 31, 2020; 129,891,856 and 127,416,740 shares issued and outstanding as of March 31, 2021 and December 31, 2020, respectively	13	13
Additional paid-in capital	1,488,337	1,385,301
Accumulated other comprehensive loss	(1,304)	(1,278)
Accumulated deficit	(836,095)	(667,184)
TOTAL STOCKHOLDERS’ EQUITY	650,951	716,852
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 1,135,584	$ 918,761

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
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	129,891,856	127,416,740
Common stock, shares outstanding	129,891,856	127,416,740

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues:
Total revenue	$ 1,976	$ 5,718
Operating expenses:
Research and development	134,870	64,979
General and administrative	25,739	12,649
Total operating expenses	160,609	77,628
Loss from operations	(158,633)	(71,910)
Other income (expense):
Interest income	164	1,755
Other expense, net	(10,246)	(7,069)
Total other income (expense)	(10,082)	(5,314)
Loss before provision for income taxes	(168,715)	(77,224)
Provision for income taxes	(196)	(16)
Net loss	$ (168,911)	$ (77,240)
Net loss per share, basic and diluted	$ (1.32)	$ (0.71)
Weighted-average shares outstanding, basic and diluted	127,742,614	108,387,913
Grant Revenue [Member]
Revenues:
Total revenue	$ 1,371	$ 5,231
Contract Revenue [Member]
Revenues:
Total revenue	$ 605	$ 487

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Net loss	$ (168,911)	$ (77,240)
Other comprehensive income (loss):
Unrealized gain (loss) on investments	(40)	844
Amortization of actuarial loss	14	5
Other comprehensive income (loss)	(26)	849
Comprehensive loss	$ (168,937)	$ (76,391)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2019	$ 423,942	$ 11	$ 793,051	$ (601)	$ (368,519)
Beginning balance (in shares) at Dec. 31, 2019		107,648,925
Reclassification of derivative liability to additional paid-in capital	29,245		29,245
Vesting of restricted common stock	427		427
Vesting of restricted common stock (in shares)		618,079
Exercise of stock options	143		143
Exercise of stock option (in shares)		83,364
Stock-based compensation	2,967		2,967
Other comprehensive income (loss)	849			849
Net loss	(77,240)				(77,240)
Ending balance at Mar. 31, 2020	380,333	$ 11	825,833	248	(445,759)
Ending balance (in shares) at Mar. 31, 2020		108,350,368
Beginning balance at Dec. 31, 2020	$ 716,852	$ 13	1,385,301	(1,278)	(667,184)
Beginning balance (in shares) at Dec. 31, 2020	127,416,740	127,416,740
Issuance of common stock in connection with a collaboration agreement	$ 85,213		85,213
Issuance of common stock in connection with a collaboration agreement (in shares)		1,924,927
Vesting of restricted common stock (in shares)		52,963
Exercise of stock options	2,352		2,352
Exercise of stock option (in shares)		497,226
Stock-based compensation	15,471		15,471
Other comprehensive income (loss)	(26)			(26)
Net loss	(168,911)				(168,911)
Ending balance at Mar. 31, 2021	$ 650,951	$ 13	$ 1,488,337	$ (1,304)	$ (836,095)
Ending balance (in shares) at Mar. 31, 2021	129,891,856	129,891,856

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (168,911)	$ (77,240)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,269	1,000
Amortization of intangible assets	133	306
Amortization of premiums on investments, net	409	562
Noncash lease expense	1,484	816
Change in estimated fair value of contingent consideration	44,462	7,165
Change in estimated fair value of derivative liability		16,796
Stock-based compensation	15,471	2,967
Other	19	5
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	943	549
Other assets	(63)	(125)
Accounts payable	(1,317)	12,944
Accrued liabilities and other long-term liabilities	(18,827)	(10,204)
Operating lease liabilities	4	(761)
Deferred revenue	35,395	(3,189)
Net cash used in operating activities	(89,529)	(48,409)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(667)	(1,302)
Purchases of investments	(5,000)	(40,472)
Maturities of investments	93,201	145,813
Proceeds from disposal of an asset held for sale		180
Net cash provided by investing activities	87,534	104,219
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of principal on financing lease obligation	(62)	(58)
Proceeds from exercise of stock options	2,352	143
Net cash provided by financing activities	87,503	85
Net increase in cash, cash equivalents and restricted cash and cash equivalents	85,508	55,895
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	451,487	122,816
Cash, cash equivalents and restricted cash and cash equivalents at end of period	536,995	178,711
NONCASH INVESTING AND FINANCING ACTIVITIES:
Property and equipment purchases included in accounts payable and accrued liabilities	378	521
Reclassification of derivative liability to additional paid-in capital		29,245
RECONCILIATION OF CASH, CASH EQUIVALENTS AND RESTRICTED CASH TO THE CONDENSED CONSOLIDATED BALANCE SHEETS:
Cash and cash equivalents	521,396	168,418
Restricted cash and cash equivalents, current	8,601	9,101
Restricted cash and cash equivalents, noncurrent	6,998	1,192
Cash, cash equivalents and restricted cash and cash equivalents at end of period	536,995	$ 178,711
Collaboration Agreement
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	$ 85,213

Organization

Organization	3 Months Ended
	Mar. 31, 2021
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. 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 and a related prospectus filed with the Securities and Exchange Commission (the “SEC”) 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 March 31, 2021, 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. As of March 31, 2021, the Company had an accumulated deficit of $836.1 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, $733.0 million of cash, cash equivalents, and short-term investments at March 31, 2021. Based on the Company’s business plans, management believes that its cash, cash equivalents, and short-term investments as of March 31, 2021 will be sufficient to fund its operations for at least the next 12 months from the issuance date of these condensed consolidated financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Basis of Presentation The Company’s condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and applicable rules and regulations of the SEC regarding interim financial reporting. The condensed consolidated financial statements include the accounts of Vir and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated upon consolidation. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair presentation of the Company’s financial information. The condensed consolidated results of operations for the three months ended March 31, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021 or for any other future annual or interim period. Certain information and footnote disclosures typically included in the Company’s annual consolidated financial statements have been condensed or omitted. As such, these interim condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes included in the Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on February 25, 2021. Use of Estimates The preparation of the condensed 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 condensed 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. Concentration of Credit Risk, Credit Loss and Other Risks and Uncertainties With the global spread of the ongoing 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. In addition, to the extent the ongoing 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 -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 condensed consolidated balance sheets. As of March 31, 2021, the Company has no off-balance sheet concentrations of credit risk. The Company is exposed to credit losses primarily through receivables from customers and collaborators and through its available-for-sale debt 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. During the three months ended March 31, 2021 and 2020, there was no allowance for losses on available-for-sale debt securities attributable to credit risk. 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 condensed 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 condensed consolidated statements of operations. The Company’s policy is not to measure an allowance for credit losses for interest receivable and to write off any uncollectible interest receivable as a reversal of interest income in the period in which it determines the interest will not be collected. 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 6—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. 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 Contract 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 (“SSP”). 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. Acquisitions Business combinations are accounted for using the acquisition method of accounting. Under the acquisition method, assets acquired, including in-process research and development (“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 condensed consolidated balance sheets. The changes in fair values of contingent consideration related to the achievement of various development 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 condensed 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 condensed consolidated balance sheets. Any change in estimated fair values, as determined at each measurement period, are recorded in the condensed consolidated statements of operations based on the nature of the related contingencies.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
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: March 31, 2021 Valuation Hierarchy Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value (in thousands) Assets: Money market funds (1) Level 1 $ 517,343 $ — $ — $ 517,343 Bank time deposits Level 2 15,000 — — 15,000 U.S. government treasuries Level 2 206,591 45 — 206,636 Total financial assets $ 738,934 $ 45 $ — $ 738,979 (1) Includes $15.6 million of restricted cash equivalents. 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. Accrued interest receivable excluded from both the fair value and amortized cost basis of the available-for-sale securities is presented within prepaid expenses and other current assets in the condensed consolidated balance sheets, and amounted to $0.7 million and $0.8 million as of March 31, 2021 and December 31, 2020, respectively. The Company did not write off any accrued interest receivable during the three months ended March 31, 2021 and 2020. As of March 31, 2021, there were no investments that have been in a continuous unrealized loss position for longer than 12 months. Total net unrealized gains recorded in accumulated other comprehensive income (loss) were immaterial at March 31, 2021. As of March 31, 2021, no securities have contractual maturities of longer than one year. Level 3 liabilities consist of contingent consideration as of March 31, 2021 and December 31, 2020. 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—Acquisitions. 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. As of March 31, 2021 , the Company calculate d the estimated fair value of the clinical and regulatory milestones using the following significant unobservable inputs: Unobservable input Value or Range (Weighted-Average) 1 Discount rates 5% - 8% (5%) Probability of achievement 14% - 72% (60%) (1) Unobservable inputs were weighted based on the relative fair value of the clinical and regulatory milestone payments. 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 March 31, 2021, 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% - 72% (67%) (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 March 31, 2021 and December 31, 2020, the estimated fair value of the contingent consideration related to the Humabs acquisition was $63.3 million and $29.2 million, respectively, with changes in the estimated fair value recorded in research and development expense in the condensed 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. In February 2021, the Company achieved one of the milestones related to a specified per-share price of its common stock resulting in a $10.0 million payable to TomegaVax’s former stockholders within 90 business days of achieving such milestone, subject to a 90-day grace period at the Company’s option in certain circumstances. As of March 31, 2021, the fair value of the remaining contingent consideration was estimated using the following significant unobservable inputs: Unobservable input Range (Weighted-Average) 1 Volatility 90% Discount rates 0% - 0.2% (0.2%) (1) Unobservable inputs were weighted based on the relative fair value of the underlying milestones As of March 31, 2021 and December 31, 2020, the estimated fair value of the contingent consideration related to the TomegaVax acquisition was $7.1 million and $6.8 million, respectively, with changes in the estimated fair value recorded in other income (expense), net in the condensed 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. The following table sets forth the changes in the estimated fair value of the Company’s Level 3 financial liabilities (in thousands): Contingent Consideration Balance at December 31, 2020 $ 35,974 Changes in fair value recognized in research and development expenses 34,100 Changes in fair value recognized in other expense, net 10,362 Reclassification of contingent consideration to accrued liabilities upon achievement of milestone (10,000 ) Balance at March 31, 2021 $ 70,436

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2021
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 vector-based vaccine platform for use in HBV, HIV, and TB. The acquisition was accounted for as an asset purchase. 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. In February 2021, the Company achieved one of the milestones related to the specified per-share price of its common stock, which resulted in a $10.0 million payable to TomegaVax’s former stockholders within 90 business days, subject to a 90-day grace period at the Company’s option in certain circumstances. 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 March 31, 2021, the estimated fair value of the embedded derivative was $7.1 million. 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. 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 (“ 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. Acquisition of Agenovir In January 2018, the Company entered into an agreement and plan of merger with Agenovir Corporation (“Agenovir”), under which the Company purchased all equity interests of Agenovir. The primary assets purchased in the acquisition were in-process research and development programs in human papillomavirus and HBV using CRISPR/Cas9. The acquisition was accounted for as an asset purchase. At the acquisition date, the Company paid cash and issued shares of Series A-2 convertible preferred stock to the former Agenovir stockholders. During a specified period following the closing of the Agenovir acquisition, the Company will be required to pay Agenovir’s former stockholders 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 March 31, 2021, therefore no amounts were recognized relating to the contingent consideration.

Grant Agreements

Grant Agreements	3 Months Ended
	Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Grant Agreements	5 . Grant Agreements Bill & Melinda Gates Foundation Grants 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. 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 $0.7 million and $4.9 million for the three months ended March 31, 2021 and 2020, 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 grant term expired on February 28, 2021. The Company has requested an extension of the TB Grant term, subject to approval, and any unused funds at the end of the term will be returned to the Bill & Melinda Gates Foundation. As of March 31, 2021, the Company had $5.5 million of unused funds received in advance and previously recorded as deferred revenue within accrued and other liabilities. 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 $0.6 million and $0.1 million for the three months ended March 31, 2021 and 2020, respectively.

Collaboration and License Agree

Collaboration and License Agreements	3 Months Ended
	Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaboration and License Agreements	6 . Collaboration and License Agreements Collaboration Agreements with GSK 2020 GSK Collaboration On June 9, 2020, the Company, Glaxo Wellcome UK Limited and Beecham S.A. ( referred to individually and the Company and certain GSK entities in April 2020 (the “ 2020 Preliminary Agreement”) (such definitive collaboration agreement, the “ 2020 GSK Agreement”). Concurrently with the execution of the 2020 Preliminary Agreement, the Company entered into a stock purchase agreement (the “ 2020 Stock Purchase Agreement”) with Glaxo Group Limited (“GGL”), an affiliate of GSK, under which GGL purchased 6,626,027 shares of the Company’s common stock on April 29, 2020, at a price per share of $ 37.73 , for an aggregate purchase price of approximately $ 250.0 million. After receipt of antitrust clearance on April 22, 2020, the Preliminary Agreement became effective as of April 29, 2020, which was also the closing date for the associated 2020 Stock Purchase Agreement between the parties (“Effective Date”). Under the terms of the 2020 GSK Agreement, the Company and GSK agreed to collaborate to research, develop and commercialize products for the prevention, treatment and prophylaxis of diseases caused by SARS-CoV-2, the virus that causes COVID-19, and potentially other coronaviruses. The collaboration is focused on the development and commercialization of three types of collaboration products under three programs: (1) antibodies targeting SARS-CoV-2, and potentially other coronaviruses (the “Antibody Program”); (2) vaccines targeting SARS-CoV-2, and potentially other coronaviruses (the “Vaccine Program”), and (3) products based on genome-wide CRISPR screening of host targets expressed in connection with exposure to SARS-CoV-2, and potentially other coronaviruses (the “Functional Genomics Program”). 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 2020 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 2020 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 2020 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 2020 GSK Agreement superseded and replaced the 2020 Preliminary Agreement between the parties. The Company considered the ASC 606 criteria for combining contracts and determined that the 2020 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 2020 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 2020 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 2020 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 2020 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 2020 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 condensed consolidated statements of operations, with any reimbursement of costs by GSK reflected as a reduction of such expenses. During the three months ended March 31, 2021, the Company recognized $18.5 million as additional research and development expense under the 2020 GSK Agreement. The Company has a payable to GSK of $13.6 million included in accrued and other liabilities as of March 31, 2021. 2021 Expanded GSK Collaboration On February 14, 2021, the Company and GSK entered into a binding preliminary collaboration agreement (the “2021 Preliminary Agreement”), under which the parties agreed to expand the 2020 GSK Agreement 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 (the “Influenza Program”); (2) an expansion of the parties’ current Functional Genomics Program to focus on functional genomics screens directed to targets associated with respiratory viruses (the “Expanded Functional Genomics Program”); and (3) additional programs to develop neutralizing mAbs directed to up to three non-influenza target pathogens selected by GSK (the “Selected Pathogens” and such programs, the “Additional Programs”). For three years following the effective date of the 2021 Preliminary 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. Under the Influenza Program, the parties will collaborate to research, develop and commercialize mAbs for the prevention, treatment or prophylaxis of influenza, including the Company’s influenza mAbs. The Company may conduct the development and clinical manufacturing activities for VIR-2482 up to completion of Phase 2 clinical trial. Provided that the Company conducts and completes Phase 2 clinical trial for VIR-2482, GSK will have the exclusive option to obtain exclusive rights to co-develop and commercialize VIR-2482 under the Influenza Program (the “VIR-2482 Option”). GSK will be the lead party for development, clinical and commercial manufacturing and commercialization activities for products under the Influenza Program (other than VIR-2482 unless and until GSK exercises the VIR-2482 Option, if applicable). The parties will mutually agree upon the allocation of responsibility for development of products under the Expanded Functional Genomics Program , and for development and early-stage manufacturing of products under the Additional Programs if and when GSK decides which Selected Pathogens to pursue. GSK will be primarily responsible for commercial manufacturing and commercialization activities for products under the Expanded Functional Genomics Program and Additional Programs , if and when selected by GSK . For each collaboration program, upon execution of the definitive agreement, the Company will grant GSK certain license rights related to the development, manufacturing and commercialization of products arising from the program . In general, the parties will share 50% of all development costs in accordance with the budget for each of the collaboration programs (other than for the Selected Pathogens and VIR-2482 unless GSK exercises the VIR-2482 Option), with each party having the right to opt-out of its co-funding obligations at specified points in development. In such case, the party continuing with the program will pay to the opt-out party a royalty on net sales of products arising from such program at rates to be agreed in a more detailed collaboration agreement (the “Definitive Collaboration Agreement”), determined by the stage of development at which the opt-out is exercised. Following the exercise of an opt-out right by a party the other party may, at its election, either pursue such program unilaterally, or also cease the conduct and funding of such collaboration product. In the absence of any opt-out, the parties will also share 50% of all profits and losses arising from any collaboration product. GSK will make an upfront payment to the Company of $225.0 million, 50% of which became payable at the effective date of the 2021 Preliminary Agreement and 50% of which will become payable at the effective date of the Definitive Collaboration Agreement. If GSK exercises the VIR-2482 Option, GSK will pay the Company an option exercise fee of $300.0 million unless certain agreed product criteria for VIR-2482 are not met, in which case the parties will negotiate an alternative option exercise fee. Upon achievement of a pre-defined regulatory milestone for the first product in the Influenza Program, which may be (i) VIR-2482 (if GSK exercised the VIR-2482 Option), (ii) a next-generation mAb, or (iii) any other influenza mAb approved by the JSC to be included in the collaboration, arising from the Influenza Program, GSK will make a milestone payment to the Company of up to $200.0 million. The parties will continue to negotiate 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. If the parties cannot reach agreement and enter into the Definitive Collaboration Agreement within 90 days following the effective date of the 2021 Preliminary Agreement, the terms of the Definitive Collaboration Agreement will be determined through an agreed process. Concurrently with the execution of the 2021 Preliminary Agreement, the Company entered into a stock purchase agreement (the “2021 Stock Purchase Agreement”) with GGL under which GGL agreed to 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 2021 Preliminary Agreement and the 2021 Stock Purchase Agreement were 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, which expiration was effective on March 24, 2021. The 2021 Preliminary Agreement and 2021 Stock Purchase Agreement consummated on March 25, 2021, which the Company used as measurement date for accounting purposes. On March 31, 2021, the Company closed the sale of 1,924,927 shares of its common stock to GGL. The Company accounted for the 2021 Preliminary Agreement as a modification to the 2020 GSK Agreement under ASC 606. The contract modification was accounted for on a prospective basis as if it were a termination of the existing contract and the creation of a new contract since the additional promised goods and services were distinct from the goods and services that were transferred on or before the effective date of the 2021 Preliminary Agreement. There was no impact to the accounting assessment of the original contract as a result of executing the 2021 Preliminary Agreement. The Company considered the ASC 606 criteria for combining contracts and determined that the 2021 Preliminary Agreement and 2021 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 $85.2 million, based on the closing stock price of $52.70 on March 25, 2021 and taking into account a discount for the lack of marketability due to the restrictions in place on the underlying shares, resulting in a $34.8 million premium received by the Company. The Company accounted for the common stock issued to GGL based on its fair market value on the transaction date and determined that the premium paid by GSK should be attributed to the transaction price of the 2021 Preliminary Agreement. The Company concluded that the 2021 Preliminary Agreement contained the following units of account: (i) the VIR-2482 Option; (ii) three distinct rights granted to GSK related to the Selected Pathogens (each, a “Selected Pathogens Right”); (iii) the right to receive license and know-how to the next-generation mAbs under the Influenza Program (the “Next Gen License Right”); (iv) the research and development activities for next generation mAbs under the Influenza Program; and (v) the research and development activities, including license rights and know-how, un der the Expanded Functional Genomics Program. The Company considered the guidance in ASC 606 to determine which of these elements of the 2021 Preliminary Agreement are performance obligations with a customer. The Company determined that the distinct performance obligations at the contract inception under ASC 606 consisted of: ( i ) the VIR-2482 Option and (ii) the three Selected Pathogens Right s , each repr esent ing a material right ; and (iii) the Next Gen License Right . All other elements of the 2021 Preliminary 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. At inception, the transaction price included fixed consideration consisting of $112.5 million, representing 50% of the upfront fee due upon the effectiveness of the 2021 Preliminary Agreement, and $34.8 million, representing the premium on the sale of common stock to GSK. In addition, the transaction price included the remaining $112.5 million of the upfront fee which is considered unconstrained at March 31, 2021 and will be received following the execution of the Definitive Collaboration Agreement. All potential future milestones and other payments were considered constrained at the inception of the 2021 Preliminary Agreement since the Company could not conclude it was probable that a significant reversal in the amount recognized would not occur. The respective estimated SSP for each of the performance obligations was determined to allocate the transaction price. The estimated SSP of each performance obligation was determined considering relevant market conditions, entity-specific factors and information about the customer, while maximizing the use of available observable inputs. For the Next Gen License Right, the Company determined that GSK will be able to benefit from the license at the time the license is granted and therefore, the related performance obligation will be satisfied at a point in time. If any of the option rights are exercised, the Company will evaluate the related promises to identify the performance obligations to be transferred and the timing of revenue recognition. If any of the option rights expire prior to being exercised, the Company will recognize any deferred revenue allocated to the option right as revenue at the time of expiration. As of March 31, 2021, the Company recorded the entire transaction price of $259.8 million as current deferred revenue on its condensed consolidated balance sheet related to these performance obligations. The Company will re-evaluate the transaction price in each reporting period. Of the $259.8 million, the Company recorded a receivable from collaboration of $112.5 million, which was subsequently received in April 2021, and a contract asset of $112.5 million as of March 31, 2021 for the portion of the upfront payment due upon execution of the Definitive Collaboration Agreement. The research and development activities for the next generation mAbs under the Influenza Program and the Expanded Functional Genomics Program 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 related products 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 in the condensed consolidated statements of operations, with any reimbursement of costs by GSK reflected as a reduction of such expenses. No additional expenses or reimbursements were recognized under the 2021 Preliminary Agreement during the three months ended March 31, 2021. 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 under a share transfer agreement in February 2020. 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. As of March 31, 2021 and December 31, 2020, the investment in Brii Bio Parent has a carrying value of $5.7 million, which is included in other assets on the condensed consolidated balance sheets. The Company also has a contract liability of $3.8 million within deferred revenue which represents deferred consideration for the remaining three 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. 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 under ASC 606. 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 three months ended March 31, 2021, the Company recognized $0.4 million 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 worl

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	7 . Property and Equipment, net Property and equipment, net consists of the following: March 31, 2021 December 31, 2020 (in thousands) Laboratory equipment $ 17,577 $ 16,769 Computer equipment 568 556 Furniture and fixtures 1,444 1,444 Leasehold improvements 7,274 7,274 Construction in progress 925 1,135 Property and equipment, gross 27,788 27,178 Less accumulated depreciation and amortization (10,497 ) (9,232 ) Total property and equipment, net $ 17,291 $ 17,946 Depreciation and amortization expenses was $1.3 million and $1.0 million for the three months ended March 31, 2021 and 2020, respectively. Accrued and Other Liabilities Accrued and other liabilities consist of the following: March 31, 2021 December 31, 2020 (in thousands) Research and development expenses $ 39,560 $ 49,384 Milestone payable 10,000 — Payroll and related expenses 5,726 17,060 Excess funds payable under grant agreements 5,459 3,467 Operating lease liabilities, current 3,568 3,625 Other professional and consulting expenses 4,037 2,595 Other expenses 1,719 805 Total accrued and other liabilities $ 70,069 $ 76,936

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	8 . Lease Agreements The Company has various 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 one 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. In February 2021, the Company entered into a new lease arrangement for office and laboratory spaces in Oregon. The lease is expected to commence in the fourth quarter of 2021 when the Company obtains access to the leased space. In addition to the operating lease agreements, the Company entered into a sale-leaseback transaction in August 2019. 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 maturity of the Company’s operating lease liabilities as of March 31, 2021 was as follows (in thousands): Amounts 2021 (excluding the three months ended March 31, 2021) $ 4,951 2022 9,707 2023 11,381 2024 10,558 2025 8,035 Thereafter 67,447 Total lease payments 112,079 Less: imputed interest (39,522 ) Less: net tenant improvement allowance yet to be received (10,287 ) Present value of operating lease liabilities $ 62,270 The following amounts were recorded in the condensed consolidated balance sheets for the periods ended: March 31, 2021 December 31, 2020 (in thousands) Operating Leases Current operating lease liabilities, net of tenant improvement allowances (1) $ 7,913 $ 7,913 Operating right-of-use assets 60,461 61,947 Accrued and other liabilities $ 3,568 $ 3,625 Operating lease liabilities, noncurrent 66,615 66,556 Total operating lease liabilities $ 70,183 $ 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. Manufacturing and Supply Letter Agreements In April 2020, the Company and Samsung Biologics Co., Ltd. (“Samsung”) entered into a binding letter agreement (the “Samsung Letter Agreement”), pursuant to which Samsung will perform development and manufacturing services for the Company’s SARS-CoV-2 antibody program. In August 2020, the Company, GlaxoSmithKline Trading Services Limited (“GSKTSL”) and Samsung entered into an Assignment and Novation Agreement effective as of July 31, 2020 pursuant to 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. In June 2020, the Company and WuXi Biologics entered into a binding letter of intent (the “WuXi Biologics Letter Agreement”), pursuant to which WuXi Biologics will perform certain development and manufacturing services for the Company’s SARS-CoV-2 antibody program. In August 2020, the Company, GSKTSL and WuXi Biologics entered into an Assignment and Novation Agreement effective as of July 29, 2020 pursuant to 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. In August 2020, GSKTSL entered into a Master Services Agreement with Samsung (the “Samsung MSA”) and a non-exclusive Master Services Agreement for Commercial Manufacture of Drug Substance with WuXi Biologics (the “WuXi Biologics MSA”) in connection with the performance of the obligations of the Company and GSK, pursuant to the 2020 GSK Agreement. In accordance with the terms of the 2020 GSK Agreement, the Company will continue to be responsible for 72.5% of the costs under each of the Samsung MSA and the WuXi Biologics 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. Pursuant to 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 obligation 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 condensed consolidated balance sheets, condensed consolidated statements of operations, or condensed consolidated statements of cash flows.

Related Party Transaction

Related Party Transaction	3 Months Ended
	Mar. 31, 2021
Related Party Transactions [Abstract]
Related Party Transaction	9 . 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.

Stock-Based Awards

Stock-Based Awards	3 Months Ended
	Mar. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Awards	1 0 . 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, 2020 9,798,282 $ 5.25 8.5 Granted 2,346,030 $ 63.63 Exercised (497,226 ) $ 4.73 Forfeited (234,088 ) $ 26.91 Outstanding at March 31, 2021 11,412,998 $ 28.72 8.7 $ 290,084 Vested and expected to vest at March 31, 2021 11,412,998 $ 28.72 8.7 $ 290,084 Vested and exercisable at March 31, 2021 2,657,960 $ 7.32 7.6 $ 116,812 As of March 31, 2021, the Company expects to recognize the remaining unamortized stock-based compensation expense of $219.9 million related to stock options, over an estimated weighted average period of 2.8 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: Three Months Ended March 31, 2021 2020 Expected term of options (in years) 6.1 6.1 Expected stock price volatility 103.1% - 106.1% 88.8% - 95.2% Risk-free interest rate 0.6% - 1.2% 0.7% - 1.2% 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 own stock. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own 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 Awards and Restricted Stock Units Activit ies The Company’s restricted stock awards (RSAs”) and restricted stock units (“RSUs”) were summarized as follows: Shares Weighted Average Grant Date Fair Value RSU RSA RSU RSA Unvested as of December 31, 2020 — 89,261 $ — $ 1.48 Granted 932,265 — $ 66.60 $ — Vested — (52,963 ) $ — $ 1.44 Cancelled (1,710 ) — $ 67.38 $ — Unvested as of March 31, 2021 930,555 36,298 $ 66.60 $ 1.53 The shares of RSA and RSU have not been included in the shares issued and outstanding. As of March 31, 2021, there was $60.2 million of total unrecognized compensation cost related to unvested RSUs, all of which is expected to be recognized over a remaining weighted-average period of 3.9 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 condensed consolidated statements of operations: Three Months Ended March 31, 2021 2020 (in thousands) Research and development $ 8,430 $ 1,488 General and administrative 7,041 1,479 Total stock-based compensation $ 15,471 $ 2,967

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Loss Per Share	1 1 . 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 March 31, 2021 2020 Options issued and outstanding 11,412,998 7,959,416 Restricted shares subject to future vesting 966,853 1,457,432 Warrants to purchase common stock — 244,444 Total 12,379,851 9,661,292

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and applicable rules and regulations of the SEC regarding interim financial reporting. The condensed consolidated financial statements include the accounts of Vir and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated upon consolidation. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair presentation of the Company’s financial information. The condensed consolidated results of operations for the three months ended March 31, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021 or for any other future annual or interim period. Certain information and footnote disclosures typically included in the Company’s annual consolidated financial statements have been condensed or omitted. As such, these interim condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes included in the Annual Report on Form 10-K for the year ended December 31, 2020, filed with the SEC on February 25, 2021.
Use of Estimates	Use of Estimates The preparation of the condensed 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 condensed 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.
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 ongoing 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. In addition, to the extent the ongoing 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 -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 condensed consolidated balance sheets. As of March 31, 2021, the Company has no off-balance sheet concentrations of credit risk. The Company is exposed to credit losses primarily through receivables from customers and collaborators and through its available-for-sale debt 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. During the three months ended March 31, 2021 and 2020, there was no allowance for losses on available-for-sale debt securities attributable to credit risk.
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 condensed 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 condensed consolidated statements of operations. The Company’s policy is not to measure an allowance for credit losses for interest receivable and to write off any uncollectible interest receivable as a reversal of interest income in the period in which it determines the interest will not be collected. 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 6—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.
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 Contract 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 (“SSP”). 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.
Acquisitions	Acquisitions Business combinations are accounted for using the acquisition method of accounting. Under the acquisition method, assets acquired, including in-process research and development (“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 condensed consolidated balance sheets. The changes in fair values of contingent consideration related to the achievement of various development 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 condensed 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 condensed consolidated balance sheets. Any change in estimated fair values, as determined at each measurement period, are recorded in the condensed consolidated statements of operations based on the nature of the related contingencies.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
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: March 31, 2021 Valuation Hierarchy Amortized Cost Gross Unrealized Holding Gains Gross Unrealized Holding Losses Aggregate Fair Value (in thousands) Assets: Money market funds (1) Level 1 $ 517,343 $ — $ — $ 517,343 Bank time deposits Level 2 15,000 — — 15,000 U.S. government treasuries Level 2 206,591 45 — 206,636 Total financial assets $ 738,934 $ 45 $ — $ 738,979 (1) Includes $15.6 million of restricted cash equivalents. 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.
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 Balance at December 31, 2020 $ 35,974 Changes in fair value recognized in research and development expenses 34,100 Changes in fair value recognized in other expense, net 10,362 Reclassification of contingent consideration to accrued liabilities upon achievement of milestone (10,000 ) Balance at March 31, 2021 $ 70,436
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 March 31, 2021 , the Company calculate d the estimated fair value of the clinical and regulatory milestones using the following significant unobservable inputs: Unobservable input Value or Range (Weighted-Average) 1 Discount rates 5% - 8% (5%) Probability of achievement 14% - 72% (60%) (1) Unobservable inputs were weighted based on the relative fair value of the clinical and regulatory milestone payments.
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 March 31, 2021, 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% - 72% (67%) (1) Unobservable inputs were weighted based on the relative fair value of the commercial milestone payments
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 March 31, 2021, the fair value of the remaining contingent consideration was estimated using the following significant unobservable inputs: Unobservable input Range (Weighted-Average) 1 Volatility 90% Discount rates 0% - 0.2% (0.2%) (1) Unobservable inputs were weighted based on the relative fair value of the underlying milestones

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment Net	Property and equipment, net consists of the following: March 31, 2021 December 31, 2020 (in thousands) Laboratory equipment $ 17,577 $ 16,769 Computer equipment 568 556 Furniture and fixtures 1,444 1,444 Leasehold improvements 7,274 7,274 Construction in progress 925 1,135 Property and equipment, gross 27,788 27,178 Less accumulated depreciation and amortization (10,497 ) (9,232 ) Total property and equipment, net $ 17,291 $ 17,946
Schedule of Accrued and Other Liabilities	Accrued and other liabilities consist of the following: March 31, 2021 December 31, 2020 (in thousands) Research and development expenses $ 39,560 $ 49,384 Milestone payable 10,000 — Payroll and related expenses 5,726 17,060 Excess funds payable under grant agreements 5,459 3,467 Operating lease liabilities, current 3,568 3,625 Other professional and consulting expenses 4,037 2,595 Other expenses 1,719 805 Total accrued and other liabilities $ 70,069 $ 76,936

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Schedule of Maturities of Operating Lease Liabilities	The maturity of the Company’s operating lease liabilities as of March 31, 2021 was as follows (in thousands): Amounts 2021 (excluding the three months ended March 31, 2021) $ 4,951 2022 9,707 2023 11,381 2024 10,558 2025 8,035 Thereafter 67,447 Total lease payments 112,079 Less: imputed interest (39,522 ) Less: net tenant improvement allowance yet to be received (10,287 ) Present value of operating lease liabilities $ 62,270
Schedule of Operating Lease Amounts Recorded in Condensed Consolidated Balance Sheets	The following amounts were recorded in the condensed consolidated balance sheets for the periods ended: March 31, 2021 December 31, 2020 (in thousands) Operating Leases Current operating lease liabilities, net of tenant improvement allowances (1) $ 7,913 $ 7,913 Operating right-of-use assets 60,461 61,947 Accrued and other liabilities $ 3,568 $ 3,625 Operating lease liabilities, noncurrent 66,615 66,556 Total operating lease liabilities $ 70,183 $ 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)	3 Months Ended
	Mar. 31, 2021
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, 2020 9,798,282 $ 5.25 8.5 Granted 2,346,030 $ 63.63 Exercised (497,226 ) $ 4.73 Forfeited (234,088 ) $ 26.91 Outstanding at March 31, 2021 11,412,998 $ 28.72 8.7 $ 290,084 Vested and expected to vest at March 31, 2021 11,412,998 $ 28.72 8.7 $ 290,084 Vested and exercisable at March 31, 2021 2,657,960 $ 7.32 7.6 $ 116,812
Summary of Restricted Stock Activity and Restricted Stock Units	The Company’s restricted stock awards (RSAs”) and restricted stock units (“RSUs”) were summarized as follows: Shares Weighted Average Grant Date Fair Value RSU RSA RSU RSA Unvested as of December 31, 2020 — 89,261 $ — $ 1.48 Granted 932,265 — $ 66.60 $ — Vested — (52,963 ) $ — $ 1.44 Cancelled (1,710 ) — $ 67.38 $ — Unvested as of March 31, 2021 930,555 36,298 $ 66.60 $ 1.53
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 condensed consolidated statements of operations: Three Months Ended March 31, 2021 2020 (in thousands) Research and development $ 8,430 $ 1,488 General and administrative 7,041 1,479 Total stock-based compensation $ 15,471 $ 2,967
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: Three Months Ended March 31, 2021 2020 Expected term of options (in years) 6.1 6.1 Expected stock price volatility 103.1% - 106.1% 88.8% - 95.2% Risk-free interest rate 0.6% - 1.2% 0.7% - 1.2% Expected dividend yield — —

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
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 March 31, 2021 2020 Options issued and outstanding 11,412,998 7,959,416 Restricted shares subject to future vesting 966,853 1,457,432 Warrants to purchase common stock — 244,444 Total 12,379,851 9,661,292

Organization - Additional Infor

Organization - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 10, 2020	Nov. 30, 2020	Mar. 31, 2021	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock price per share			$ 0.0001	$ 0.0001
Accumulated deficit			$ 836,095	$ 667,184
Cash, cash equivalents and short-term investments			$ 733,000
Common Stock | Sales Agreement
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Issuance of common stock, shares			0
Common stock price per share		$ 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
Follow-on Offering | Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Issuance of common stock, shares	8,214,285
Common stock price per share	$ 42
Gross proceeds from the offering	$ 345,000
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) - USD ($)	Mar. 31, 2021	Mar. 31, 2020
Accounting Policies [Abstract]
Allowance for losses on available-for-sale debt securities	$ 0	$ 0

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	Mar. 31, 2021		Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost	$ 738,934		$ 722,036
Financial Assets, Gross Unrealized Holding Gains	45		91
Financial Assets, Gross Unrealized Holding Losses			(6)
Financial Assets, Aggregate Fair Value	738,979		722,121
Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost	517,343	[1]	421,835	[2]
Financial Assets, Aggregate Fair Value	517,343	[1]	421,835	[2]
Level 2 | Bank Time Deposits
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost	15,000
Financial Assets, Aggregate Fair Value	15,000
Level 2 | U.S. Government Treasuries
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets, Amortized Cost	206,591		300,201
Financial Assets, Gross Unrealized Holding Gains	45		91
Financial Assets, Gross Unrealized Holding Losses			(6)
Financial Assets, Aggregate Fair Value	$ 206,636		$ 300,286
[1]	Includes $15.6 million of restricted cash equivalents.
[2]	Includes $14.9 million of restricted cash equivalents.

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 Millions	Mar. 31, 2021	Dec. 31, 2020
Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Restricted cash equivalents	$ 15.6	$ 14.9

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Feb. 28, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Write off of accrued interest receivable	$ 0	$ 0
Humabs
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated fair value of contingent consideration	63,300,000			$ 29,200,000
TomegaVax
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated fair value of contingent consideration	$ 7,100,000			6,800,000
TomegaVax | TomegaVax Letter Agreement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated fair value of contingent consideration			$ 10,000,000
Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities contractual term	1 year
Prepaid Expenses and Other Current Assets
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Accrued interest receivable excluded from fair value and amortized cost basis of available for sale securities	$ 700,000			$ 800,000
Contingent Consideration Liability | TomegaVax | TomegaVax Letter Agreement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated fair value of contingent consideration			$ 10,000,000

Fair Value Measurements - Estim

Fair Value Measurements - Estimated Fair Value of Significant Unobservable Inputs (Details)	Mar. 31, 2021
Humabs | Clinical and Regulatory Milestones | Discount Rates | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.05	[1]
Humabs | Clinical and Regulatory Milestones | Discount Rates | Maximum
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 | Discount Rates | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.05	[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	0.72	[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	0.60	[1]
Humabs | Commercial Milestones | Discount Rates
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	0.72	[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	0.67	[2]
Humabs | Commercial Milestones | Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.60	[2]
TomegaVax | Discount Rates | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0	[3]
TomegaVax | Discount Rates | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.002	[3]
TomegaVax | Discount Rates | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.002	[3]
TomegaVax | Measurement Input, Price Volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value contingent consideration measurement input	0.90	[3]
[1]	Unobservable inputs were weighted based on the relative fair value of the clinical and regulatory milestone payments.
[2]	Unobservable inputs were weighted based on the relative fair value of the commercial milestone payments
[3]	Unobservable inputs were weighted based on the relative fair value of the underlying milestones

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Changes in Estimated Fair Value of Financial Liabilities (Details) - Level 3 - Contingent Consideration Liability $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2020	$ 35,974
Reclassification of contingent consideration to accrued liabilities upon achievement of milestone	(10,000)
Balance at March 31, 2021	70,436
Research and Development Expense
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Changes in fair value recognized	34,100
Other Expense
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Changes in fair value recognized	$ 10,362

Acquisitions - Additional Infor

Acquisitions - Additional Information (Details)	1 Months Ended				3 Months Ended
	Feb. 28, 2021USD ($)Milestone	Oct. 31, 2020USD ($)Milestone	May 31, 2020USD ($)Milestone	Sep. 30, 2016USD ($)$ / shares	Mar. 31, 2021USD ($)Milestone	Dec. 31, 2020USD ($)	Jan. 31, 2018USD ($)	Aug. 31, 2017USD ($)
TomegaVax | TomegaVax Letter Agreement
Business Acquisition [Line Items]
Milestone payments aggregate amount payable, maximum				$ 30,000,000
Minimum common stock conversion price for milestone payments consideration | $ / shares				$ 45
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.
Number of milestones achieved | Milestone	1
Contingent consideration recognized	$ 10,000,000
Milestone payments, amount payable term	90 days
Estimated fair value of embedded derivative					$ 7,100,000
Humabs
Business Acquisition [Line Items]
Contingent consideration recognized					63,300,000	$ 29,200,000
Humabs | HBV Product
Business Acquisition [Line Items]
Contingent consideration recognized					$ 63,300,000
Additional consideration payable upon achievement of specified milestone events, maximum								$ 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, maximum								$ 105,000,000
Humabs | SARS-CoV-2 Product
Business Acquisition [Line Items]
Number of specified clinical milestones achieved | Milestone		1
Specified clinical development milestones payment		$ 10,000,000
Agenovir
Business Acquisition [Line Items]
Number of milestones achieved | Milestone					0
Contingent consideration recognized					$ 0
Agenovir | HBV Product
Business Acquisition [Line Items]
Milestone payments aggregate amount payable, maximum							$ 135,000,000

Grant Agreements - Additional I

Grant Agreements - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Feb. 29, 2020	Mar. 16, 2018	Jan. 26, 2018
Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants	$ 1,371,000	$ 5,231,000
Human Immunodeficiency Virus ("HIV") Grant
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount			$ 8,600,000
Human Immunodeficiency Virus ("HIV") Grant | Grant Revenue [Member] | Bill And Melinda Gates Foundation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants	700,000	4,900,000
Human Immunodeficiency Virus ("HIV") Grant | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount. maximum					$ 12,200,000
Tuberculosis ("TB") Grant
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Unused funds received in advance	$ 5,500,000
Grant agreement expiration date	Feb. 28, 2021
Tuberculosis ("TB") Grant | Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants	$ 600,000	$ 100,000
Tuberculosis ("TB") Grant | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount. maximum				$ 14,900,000

Collaboration and License Agr_2

Collaboration and License Agreements - Additional Information (Details)

Mar. 25, 2021USD ($)$ / shares

Feb. 14, 2021USD ($)program

Apr. 29, 2020USD ($)Unit$ / sharesshares

Jun. 30, 2020USD ($)

Mar. 31, 2020USD ($)shares

Sep. 30, 2019USD ($)

Aug. 31, 2019USD ($)

Sep. 30, 2018USD ($)

Jul. 31, 2018USD ($)

May 31, 2018USD ($)

Oct. 31, 2017USD ($)shares

Mar. 31, 2021USD ($)shares

Jun. 30, 2020USD ($)

Mar. 31, 2020USD ($)

Sep. 30, 2019USD ($)

Sep. 30, 2020

Dec. 31, 2020USD ($)

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Current deferred revenue

$ 262,929,000

$ 6,451,000

Contract asset

112,500,000

Research and development

$ 134,870,000

$ 64,979,000

2020 Stock Purchase Agreement | GGL

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Issuance of common stock, shares | shares

6,626,027

Share purchase price per share | $ / shares

$ 37.73

Issuance of common stock, value

$ 250,000,000

Preliminary Collaboration Agreement | 2020 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 2020 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.

Number of units of account | Unit

4

Additional research and development expense

$ 18,500,000

Preliminary Collaboration Agreement | 2020 GSK | Accrued and Other Liabilities

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Payable

13,600,000

Preliminary Collaboration Agreement | 2021 GSK

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

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

3 years

Number of separate programs | program

3

Percentage of share development costs

50.00%

Percentage of share Profit and loss

50.00%

Upfront payment receivable

$ 225,000,000

Percentage of upfront payment receivable at effective date of agreement

50.00%

Option exercise fee to be received

$ 300,000,000

Fixed consideration

$ 112,500,000

Percentage of upfront fee

50.00%

Premium paid on sale price of common stock

$ 34,800,000

Remaining upfront fee

112,500,000

Current deferred revenue

259,800,000

Receivable from collaboration

112,500,000

Contract asset

112,500,000

Research and development

$ 0

Preliminary Collaboration Agreement | 2021 GSK | Maximum

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Pre-defined regulatory milestone payment

$ 200,000,000

Preliminary Collaboration Agreement | Antibody Program | 2020 GSK

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Percentage of development costs

72.50%

Antibody license transaction price

$ 43,300,000

Total revenue

$ 43,300,000

Preliminary Collaboration Agreement | Vaccine Program | 2020 GSK

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Percentage of development costs

27.50%

2020 Preliminary Collaboration Agreement and 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 | $ / shares

$ 36.70

Premium received on sale price of common stock

$ 43,300,000

Definitive Collaboration Agreement | 2021 GSK

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Percentage of upfront payment receivable at effective date of agreement

50.00%

2021 Stock Purchase Agreement | GGL

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Issuance of common stock, shares | shares

1,924,927

Common stock to be issued, value

$ 120,000,000

2021 Preliminary Collaboration Agreement and Stock Purchase Agreement | GGL | ASC 606

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Fair market value of the common stock issued

$ 85,200,000

Common stock price per share | $ / shares

$ 52.70

Premium received on sale price of common stock

$ 34,800,000

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

Sales milestone receivable

175,000,000

175,000,000

Contract liability

2,700,000

2,700,000

Option exercise fee received

20,000,000

Determined transaction price

22,700,000

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

$ 3,800,000

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 | Maximum | China Territory

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Sales milestone receivable

175,000,000

Brii Agreement | Brii Bio | Maximum | United States

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

$ 5,700,000

Brii Agreement | Alnylam Pharmaceuticals Inc | Research and Development Expense

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

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 | Biological Materials | Brii Bio Parent

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Total revenue

$ 400,000

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 | shares

1,111,111

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 | shares

1,111,111

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

30 days

Estimated fair value of the derivative liability

$ 29,200,000

29,200,000

Contractual payments

15,000,000

Milestone payments paid.

15,000,000

Change in fair value of Milestone Shares

$ 16,800,000

Expenses incurred under agreement

$ 900,000

2,300,000

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 sales milestone payment

100,000,000

Maximum aggregate sales milestone payment

$ 250,000,000

Development and Manufacturing Collaboration Agreement | WuXi Biologics

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.

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

Royalty obligation period from date of first commercial sale

12 years

Rockefeller Agreement | Commercialization | Rockefeller

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Payment of annual license maintenance fees

1,000,000

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

$ 80,300,000

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

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Specified development milestones and annual license maintenance fees

$ 1,300,000

License maintenance fees

$ 0

$ 0

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

Development, regulatory, and commercial milestone payments

$ 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]

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

Specified development milestones payment

$ 800,000

2019 Xencor Agreement | HBV Research Programs | Xencor

Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]

Maximum aggregate milestone payments

77,800,000

Specified development milestones payment

$ 300,000

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	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 27,788	$ 27,178
Less accumulated depreciation and amortization	(10,497)	(9,232)
Total property and equipment, net	17,291	17,946
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	17,577	16,769
Computer Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	568	556
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	1,444	1,444
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	7,274	7,274
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 925	$ 1,135

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization expenses	$ 1,269	$ 1,000

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Accrued and Other Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Research and development expenses	$ 39,560	$ 49,384
Milestone payable	10,000
Payroll and related expenses	5,726	17,060
Excess funds payable under grant agreements	5,459	3,467
Operating lease liabilities, current	3,568	3,625
Other professional and consulting expenses	4,037	2,595
Other expenses	1,719	805
Total accrued and other liabilities	$ 70,069	$ 76,936

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	1 Months Ended	3 Months Ended
	Aug. 31, 2020	Mar. 31, 2021
Commitments And 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 one to five years.
GSKTSL | WuXi Biologics MSA and Samsung MSA | Antibody Program
Commitments And Contingencies [Line Items]
Percentage of development costs	72.50%
GSK | WuXi Biologics MSA and Samsung MSA | Antibody Program
Commitments And Contingencies [Line Items]
Percentage of development costs	27.50%
Minimum [Member]
Commitments And Contingencies [Line Items]
Lessee, operating lease, renewal term		1 year
Maximum
Commitments And Contingencies [Line Items]
Lessee, operating lease, renewal term		5 years

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Maturities of Operating Lease Liabilities (Details) $ in Thousands	Mar. 31, 2021USD ($)
Commitments And Contingencies Disclosure [Abstract]
2021 (excluding the three months ended March 31, 2021)	$ 4,951
2022	9,707
2023	11,381
2024	10,558
2025	8,035
Thereafter	67,447
Total lease payments	112,079
Less: imputed interest	(39,522)
Less: net tenant improvement allowance yet to be received	(10,287)
Present value of operating lease liabilities	$ 62,270

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Operating Lease Amounts Recorded in Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Operating Leases
Current operating lease liabilities, net of tenant improvement allowances	[1]	$ 7,913	$ 7,913
Operating right-of-use assets		60,461	61,947
Operating lease liabilities, current		$ 3,568	$ 3,625
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]		Accrued and other liabilities	Accrued and other liabilities
Operating lease liabilities, noncurrent		$ 66,615	$ 66,556
Total operating lease liabilities		$ 70,183	$ 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 - Summary of

Stock-Based Awards - Summary of Stock Option Plans Activity (Details) - Stock Option - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options,Outstanding, Beginning Balance	9,798,282
Number of Options,Granted	2,346,030
Number of Options,Exercised	(497,226)
Number of Options,Forfeited	(234,088)
Number of Options,Outstanding, Ending Balance	11,412,998	9,798,282
Number of Options,Vested and expected to vest	11,412,998
Number of Options,Vested and exercisable	2,657,960
Weighted Average Exercise Price, Beginning Balance	$ 5.25
Weighted Average Exercise Price, Granted	63.63
Weighted Average Exercise Price, Exercised	4.73
Weighted Average Exercise Price, Forfeited	26.91
Weighted Average Exercise Price, Ending Balance	28.72	$ 5.25
Weighted Average Exercise Price,Vested and expected to vest	28.72
Weighted Average Exercise Price,Vested and exercisable	$ 7.32
Weighted Average Remaining Contractual Term	8 years 8 months 12 days	8 years 7 months 6 days
Weighted Average Remaining Contractual Term,Vested and expected to vest	8 years 8 months 12 days
Weighted Average Remaining Contractual Term,Vested and exercisable	7 years 7 months 6 days
Aggregate Intrinsic Value, Balance	$ 290,084
Aggregate Intrinsic Value, Vested and expected to vest	290,084
Aggregate Intrinsic Value, Vested and exercisable	$ 116,812

Stock-Based Awards - Additional

Stock-Based Awards - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)
Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unamortized stock-based compensation expense related to stock option	$ 219.9
Estimated weighted average period	2 years 9 months 18 days
RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Estimated weighted average period	3 years 10 months 24 days
Unrecognized compensation cost related to unvested restricted stock	$ 60.2

Stock-Based Awards - Summary _2

Stock-Based Awards - Summary of Assumptions Used for Estimating the Fair Value of Stock Options Granted (Details)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected term of options (in years)	6 years 1 month 6 days	6 years 1 month 6 days
Expected stock price volatility,minimum	103.10%	88.80%
Expected stock price volatility,maximum	106.10%	95.20%
Risk-free interest rate, minimum	0.60%	0.70%
Risk-free interest rate, maximum	1.20%	1.20%

Stock-Based Awards - Summary _3

Stock-Based Awards - Summary of Restricted Stock Activity and Restricted Stock Units (Details)	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Restricted Stock Units (RSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Granted | shares	932,265
Number of Shares, Cancelled | shares	(1,710)
Number of Shares, Unvested, Ending Balance | shares	930,555
Weighted Average Grant Date Fair Value, Granted | $ / shares	$ 66.60
Weighted Average Grant Date Fair Value, Cancelled | $ / shares	67.38
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 66.60
Restricted Stock Awards (RSAs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Unvested, Beginning Balance | shares	89,261
Number of Shares, Vested | shares	(52,963)
Number of Shares, Unvested, Ending Balance | shares	36,298
Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 1.48
Weighted Average Grant Date Fair Value, Vested | $ / shares	1.44
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 1.53

Stock-Based Awards - Summary _4

Stock-Based Awards - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 15,471	$ 2,967
Research and Development Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	8,430	1,488
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 7,041	$ 1,479

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Potentially Dilutive Securities Not Included in Diluted Per Share Calculations (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive shares excluded from calculation of diluted net loss per share (in shares)	12,379,851	9,661,292
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)	11,412,998	7,959,416
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)	966,853	1,457,432
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