Vaxcyte (PCVX) 10-Q 8 May 23 2023 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2023	May 04, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Entity Registrant Name	VAXCYTE, INC.
Entity Central Index Key	0001649094
Current Fiscal Year End Date	--12-31
Entity Emerging Growth Company	false
Entity File Number	001-39323
Entity Tax Identification Number	46-4233385
Entity Address, Address Line One	825 Industrial Road
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	San Carlos
Entity Address, State or Province	CA
Entity Incorporation, State or Country Code	DE
Entity Address, Postal Zip Code	94070
City Area Code	650
Local Phone Number	837-0111
Document Quarterly Report	true
Document Transition Report	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		93,706,790
Entity Filer Category	Large Accelerated Filer
Entity Interactive Data Current	Yes
Entity Current Reporting Status	Yes
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	PCVX
Security Exchange Name	NASDAQ

Condensed Balance Sheets (Unaud

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 380,451	$ 834,657
Short-term investments	441,587	96,719
Prepaid expenses and other current assets	18,636	11,179
Total current assets	840,674	942,555
Property and equipment, net	15,205	10,360
Operating lease right-of-use assets	19,658	21,288
Long-term investments	127,815	26,549
Restricted cash	871	871
Other assets	3,940	4,555
Total noncurrent assets	167,489	63,623
Total assets	1,008,163	1,006,178
Current liabilities:
Accounts payable	11,615	9,795
Accrued compensation	1,879	1,180
Accrued manufacturing expenses	14,955	8,265
Accrued expenses	18,351	15,375
Operating lease liabilities — current	5,947	5,910
Total current liabilities	52,747	40,525
Operating lease liabilities — long-term	10,638	12,031
Other liabilities	7	9
Total liabilities	63,392	52,565
Commitments and contingencies (Note 6)
Stockholders' Equity
Preferred stock, $0.001 par value - 10,000,000 shares authorized at March 31, 2023 and December 31, 2022; no shares issued and outstanding at March 31, 2023 and December 31, 2022	0	0
Common stock, $0.001 par value - 500,000,000 shares authorized at March 31, 2023 and December 31, 2022; 80,640,851 and 79,470,670 shares issued and outstanding at March 31, 2023 and December 31, 2022, respectively	84	82
Additional paid-in capital	1,527,228	1,476,018
Accumulated other comprehensive gain (loss)	47	(361)
Accumulated deficit	(582,588)	(522,126)
Total stockholders' equity	944,771	953,613
Total liabilities and stockholders' equity	$ 1,008,163	$ 1,006,178

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Mar. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
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	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	80,640,851	79,470,670
Common stock, shares outstanding	80,640,851	79,470,670

Condensed Statements of Operati

Condensed Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating expenses:
Research and development	$ 58,080	$ 31,678
General and administrative	13,112	7,543
Total operating expenses	71,192	39,221
Loss from operations	(71,192)	(39,221)
Other income (expense), net:
Interest income	10,393	134
Grant income	654	160
Realized losses on marketable securities	0	(65)
Foreign currency transaction (losses) gains	(317)	6
Total other income (expense), net	10,730	235
Net loss	$ (60,462)	$ (38,986)
Net loss per share, basic	$ (0.70)	$ (0.68)
Net loss per share, diluted	$ (0.70)	$ (0.68)
Weighted-average shares outstanding, basic	86,206,817	57,547,808
Weighted-average shares outstanding, diluted	86,206,817	57,547,808

Condensed Statements of Compreh

Condensed Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Statement of Comprehensive Income [Abstract]
Net Loss	$ (60,462)	$ (38,986)
Other comprehensive loss:
Unrealized gains (losses) on investments	408	(592)
Comprehensive loss	$ (60,054)	$ (39,578)

Condensed Statements of Redeema

Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Follow on public offering	Follow on public offering Common Stock	Follow on public offering Additional Paid-in Capital	At the market offering	At the market offering Common Stock	At the market offering Additional Paid-in Capital
Beginning balance at Dec. 31, 2021	$ 284,018	$ 56	$ 582,844	$ (298,641)	$ (241)
Beginning balance, shares at Dec. 31, 2021		53,031,978
Exercise of stock options	282		282
Exercise of stock options (in shares)		91,044
Vesting of early exercised stock options	2		2
Issuance of common stock, value						$ 107,622	$ 3	$ 107,619	$ 3,098		$ 3,098
Issuance of common stock, shares							3,250,000			126,522
Release of restricted stock units	0
Stock-based compensation expense	4,099		4,099
Unrealized losses on investments	(592)				(592)
Net Loss	(38,986)			(38,986)
Ending balance at Mar. 31, 2022	359,543	$ 59	697,944	(337,627)	(833)
Ending balance, shares at Mar. 31, 2022		56,499,544
Beginning balance at Dec. 31, 2022	953,613	$ 82	1,476,018	(522,126)	(361)
Beginning balance, shares at Dec. 31, 2022		79,470,670
Exercise of stock options	502	$ 1	501
Exercise of stock options (in shares)		100,964
Vesting of early exercised stock options	2		2
Issuance of common stock, value	41,787									$ 1	$ 41,786
Issuance of common stock, shares										1,041,536
Release of restricted stock units	(727)		(727)
Release of restricted stock units, shares		27,681
Stock-based compensation expense	9,648		9,648
Unrealized losses on investments	408				408
Net Loss	(60,462)			(60,462)
Ending balance at Mar. 31, 2023	$ 944,771	$ 84	$ 1,527,228	$ (582,588)	$ 47
Ending balance, shares at Mar. 31, 2023		80,640,851

Condensed Statements of Redee_2

Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Parenthetical) - Common Stock - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
At the market offering
Issuance costs	$ 1,237	$ 114
Follow on public offering
Issuance costs		$ 7,376

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net loss	$ (60,462)	$ (38,986)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	712	582
Stock-based compensation expense	9,648	4,099
Amortization of operating right-of-use assets	1,630	1,787
Net amortization of premiums on investments	(5,990)	321
Loss on disposal of fixed assets	0	44
Asset impairment charges	0	57
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(4,702)	2,791
Other assets	615	(1,577)
Operating lease liabilities	(1,356)	5,619
Accounts payable	1,789	(1,933)
Accrued compensation	699	(2,185)
Accrued manufacturing expenses	6,689	2,416
Accrued expenses	3,038	(737)
Net cash used in operating activities	(47,690)	(27,702)
Cash flows from investing activities:
Purchases of property and equipment	(5,609)	(2,920)
Purchases of investments	(483,779)	(6,972)
Maturities of investments	40,160	59,551
Sale of investments	1,127	0
Proceeds from sale of property and equipment	0	7
Net cash (used in) provided by investing activities	(448,101)	49,666
Cash flows from financing activities:
Proceeds from exercise of common stock options	502	282
Proceeds from issuance of common stock related to at-the-market offering, net of issuance costs	41,787	3,115
Proceeds from issuance of common stock from follow-on offering, net of issuance costs	0	107,622
Release of restricted stock units	(727)	0
Net cash provided by financing activities	41,562	111,019
Effect of exchange rate changes on cash and cash equivalents	23	(227)
Net (decrease) increase in cash, cash equivalents and restricted cash	(454,206)	132,756
Cash, cash equivalents and restricted cash, beginning of period	835,528	69,856
Cash, cash equivalents and restricted cash, end of period	381,322	202,612
Supplemental disclosures of non-cash investing and financing activities:
Purchases of property and equipment recorded in accounts payable and accrued expenses	57	664
Deferred offering costs included in accounts payable and accrued expenses	$ 0	$ 23

Company Organization and Nature

Company Organization and Nature of Business	3 Months Ended
	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Company Organization and Nature of Business	1. Company Organization and Nature of Business Vaxcyte, Inc. (“we,” “us,” “the Company,” or “Vaxcyte”), headquartered in San Carlos, California, was incorporated in the state of Delaware on November 27, 2013 as SutroVax, Inc. and we changed our name to Vaxcyte, Inc. on May 15, 2020. We are a clinical-stage vaccine innovation company engineering high-fidelity vaccines to protect humankind from the consequences of bacterial diseases. We are developing broad-spectrum conjugate and novel protein vaccines to prevent or treat bacterial infectious diseases. We are re-engineering the way highly complex vaccines are made through modern synthetic techniques, including advanced chemistry and the XpressCF cell-free protein synthesis platform, exclusively licensed from Sutro Biopharma, Inc. (“Sutro Biopharma”). Unlike conventional cell-based approaches, our system for producing difficult-to-make proteins and antigens is intended to accelerate our ability to efficiently create and deliver high-fidelity vaccines with enhanced immunological benefits. Our primary activities since incorporation have been to perform research and development, undertake preclinical and clinical studies and conduct manufacturing activities in support of our product development efforts; organize and staff our Company; establish our intellectual property portfolio; and raise capital to support and expand such activities.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	2. Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation These condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP, and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and footnote disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted in accordance with such rules and regulations. Unaudited Interim Condensed Financial Statements The condensed balance sheet as of March 31, 2023, the condensed statements of operations, comprehensive loss and stockholders’ equity for the three months ended March 31, 2023 and 2022 and the condensed statements of cash flows for the three months ended March 31, 2023 and 2022 are unaudited. The unaudited interim condensed financial statements have been prepared on the same basis as the audited annual financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair statement of our financial information. The financial data disclosed in the footnotes to the condensed financial statements related to the three months ended March 31, 2023 and 2022 are also unaudited. The results of operations for the three months ended March 31, 2023 are not necessarily indicative of the results to be expected for the year ending December 31, 2023 or for any other future annual or interim period. These interim condensed financial statements should be read in conjunction with our audited financial statements and related notes thereto for the year ended December 31, 2022 included in our Annual Report on Form 10-K filed with the SEC on February 27, 2023. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and expenses and the disclosure of contingent assets and liabilities at the date of the financial statements. On an ongoing basis, we evaluate our estimates and assumptions, including those related to stock-based compensation expense, accruals for certain research and development costs, the valuation of deferred tax assets and income taxes. Management bases our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ materially from those estimates. Cash, Cash Equivalents and Restricted Cash We consider all highly liquid investments purchased with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market funds and commercial paper and are stated at their fair values. Restricted cash consists of a standby letter of credit, which was issued in the first quarter of 2021, that serves as collateral for the lease agreement for our current corporate headquarters. Cash, cash equivalents and restricted cash as reported within the condensed balance sheets that total to the same amounts shown in the condensed statement of cash flows are as follows: March 31, December 31, 2023 2022 (in thousands) Cash and cash equivalents $ 380,451 $ 834,657 Restricted cash 871 871 Cash, cash equivalents and restricted cash $ 381,322 $ 835,528 Investments Our investments have been classified and accounted for as available-for-sale securities. Fixed income securities consist of U.S. Treasury securities, U.S. government agency securities, corporate debt, commercial paper and asset-backed securities. These securities are recorded on the condensed balance sheets at fair value. Unrealized gains and losses on these securities are included as a separate component of accumulated other comprehensive gain (loss). The cost of investment securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in other income (expense), net. Realized gains and losses are also included in other income (expense), net. When the fair value of a debt security declines below its amortized cost basis, any portion of that decline attributable to credit losses, to the extent expected to be nonrecoverable before the sale of the security, is recognized in our condensed statements of operations. When the fair value of a debt security declines below its amortized cost basis due to changes in interest rates, such amounts are recorded in other comprehensive loss, and are recognized in our condensed statements of operations only if we sell or intend to sell the security before recovery of its cost basis. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted average of shares of common stock outstanding, including pre-funded warrants issued, during the period, without consideration for common stock equivalents. Shares of common stock into which the pre-funded warrants may be exercised are considered outstanding for the purposes of computing net loss per share because the shares may be issued for little consideration, are fully vested and are exercisable after the original issuance date. Diluted net loss per share is the same as basic net loss per share since the effects of potentially dilutive securities are antidilutive given the net loss for each period presented. Leases We determine if an arrangement is a lease at inception. In addition, we determine whether a lease meets the classification criteria of a finance or operating lease at the lease commencement date considering whether: (i) the lease transfers ownership of the underlying asset to the lessee at the end of the lease term; (ii) the lease grants the lessee an option to purchase the underlying asset that the lessee is reasonably certain to exercise; (iii) the lease term is for a major part of the remaining economic life of the underlying asset; (iv) the present value of the sum of the lease payments and residual value guaranteed by the lessee equals or exceeds substantially all of the fair value of the underlying asset; and (v) the underlying asset is such a specialized nature that it is expected to have no alternative use to the lessor at the end of the lease term. As of March 31, 2023, our lease population consisted of office operating leases. As of March 31, 2023 , we did no t have finance leases. Operating leases are included in Operating lease right-of-use (“ROU”) assets, Operating lease liabilities — current and Operating lease liabilities — long term in our condensed balance sheet. ROU assets represent our right to use the underlying assets for the lease term and lease liabilities represent our obligation to make lease payments arising from the leases. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the present value of lease payments, if the rate implicit in the lease is not readily determinable, we use our incremental borrowing rate based on the information available at the lease commencement date. We determine the incremental borrowing rate based on an analysis of corporate bond yields with a credit rating similar to ours. The determination of our incremental borrowing rate requires management judgment, including development of a synthetic credit rating and cost of debt, as we currently do not carry any debt. We believe that the estimates used in determining the incremental borrowing rate are reasonable based upon current facts and circumstances. Applying different judgment to the same facts and circumstances could yield a different incremental borrowing rate. The operating lease ROU assets also include adjustments for prepayments and accrued lease payments and exclude lease incentives. ROU assets and lease liabilities may include options to extend or terminate leases if it is reasonably certain that we will exercise such options. Lease payments which are fixed and determinable are amortized as rent and lease expense on a straight-line basis over the expected lease term. Variable lease costs, which are dependent on usage, a rate or index, including common area maintenance charges, are expensed as incurred. Lease agreements that include lease and non-lease components are accounted for as a single lease component. Lease agreements with non-cancelable terms of less than 12 months are not recorded on our condensed balance sheets. Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject us to a concentration of credit risk consist primarily of cash, cash equivalents and investments. We invest in money market funds, U.S. Treasury securities, U.S. government agency securities, corporate debt, commercial paper and asset-backed securities. We maintain bank deposits in federally insured financial institutions and these deposits may exceed federally-insured limits. We are exposed to credit risk in the event of a default by the financial institutions holding our cash and issuers of investments to the extent recorded on the condensed balance sheets. For example, on March 10, 2023, the California Department of Financial Protection and Innovation took control of Silicon Valley Bank (“SVB”) and appointed the Federal Deposit Insurance Corporation (“FDIC”) as receiver. While SVB was our primary bank at the time, we maintained banking relationships with other major banks. The substantial majority of funds we held at SVB, which included cash, cash equivalents and investments were held in custodial accounts of a third-party institution for which SVB Asset Management was the advisor (“SVB Custodial Accounts”). On March 12, 2023, the FDIC confirmed that depositors of SVB would have access to all of their money and, as a result, we regained access to all of our funds deposited with SVB. The FDIC subsequently transferred SVB’s deposits and loans to a newly created bridge bank, named Silicon Valley Bridge Bank, N.A. (“Silicon Valley Bridge Bank”). On March 26, 2023, the FDIC announced that First Citizens Bank & Trust Company (“First Citizens Bank”) had agreed to purchase and assume all deposits and loans of Silicon Valley Bridge Bank. Management believes that we are not exposed to significant credit risk as our deposits are held at First Citizens Bank, and our investments are held under separate financial institution custodial accounts, each of which management continues to believe to be of high credit quality. We have not experienced any losses on these deposits or investments as a result of this market event. While we were able to recover all deposited amounts from SVB, and continue to have access to all investments held in the SVB Custodial Accounts, there can be no assurance that our current or future banks will not face similar risks as SVB or that we will be able to recover in full our deposits in the event of similar closures. Our investment policy limits investments to money market funds, certain types of debt securities issued by the U.S. Government and its agencies, corporate debt, commercial paper and asset-backed securities, and places restrictions on the credit ratings, maturities and concentration by type and issuer. We have not experienced any significant losses on our deposits of cash, cash equivalents or investments. We are subject to supplier concentration risk from our suppliers. Although we are working to establish secondary sources of supply, we currently source several of our critical raw materials from single-source suppliers. We also use one contract manufacturing organization (“CMO”), Lonza Ltd. (“Lonza”), to handle most of our manufacturing activities for our VAX-24 and VAX-31 programs. If we were to experience disruptions in raw materials supplied by our suppliers, or in manufacturing activities at Lonza, we may experience significant delays in our product development timelines and may incur substantial costs to secure alternative sources of raw materials or manufacturing. Our future results of operations involve a number of other risks and uncertainties. Factors that could affect our future operating results and cause actual results to vary materially from expectations include, but are not limited to: our early stages of clinical vaccine development; our ability to advance vaccine candidates into, and successfully complete, clinical trials on the timelines we project; our ability to adequately demonstrate sufficient safety and immunogenicity or efficacy of our vaccine candidates; our ability to enroll subjects in our ongoing and future clinical trials; our ability to successfully manufacture and supply our vaccine candidates for clinical trials; our ability to obtain additional capital to finance our operations; our ability to obtain, maintain and protect our intellectual property rights; developments relating to our competitors and our industry, including competing vaccine candidates; general and market conditions; and other risks and uncertainties, including those more fully described in the “Risk Factors” section of this Quarterly Report on Form 10-Q.

Fair Value Measurements and Fai

Fair Value Measurements and Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements and Fair Value of Financial Instruments	3. Fair Value Measurements and Fair Value of Financial Instruments Assets and liabilities recorded at fair value on a recurring basis in the condensed balance sheets, as well as assets and liabilities measured at fair value on a non-recurring basis or disclosed at fair value, are categorized based upon the level of judgment associated with inputs used to measure their fair values. The accounting guidance for fair value provides a framework for measuring fair value and requires certain disclosures about how fair value is determined. Fair value is defined as the price that would be received upon the sale of an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The accounting guidance also establishes a three-level valuation hierarchy that prioritizes the inputs to valuation techniques used to measure fair value based upon whether such inputs are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect market assumptions made by the reporting entity. The three-level hierarchy for the inputs to valuation techniques is briefly summarized as follows: Level 1— Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2— Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities 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 related assets or liabilities; and Level 3 — Unobservable inputs based on our own data or other assumptions that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. Changes in the ability to observe valuation inputs may result in a reclassification of levels of certain securities within the fair value hierarchy. We recognize transfers into and out of levels within the fair value hierarchy in the period in which the actual event or change in circumstances that caused the transfer occurs. Level 1 securities consist of highly liquid money market funds for which the carrying amounts approximate their fair values due to their short maturities. U.S. Treasury securities are valued using Level 1 inputs based on unadjusted, quoted prices in active markets that are observable at the measurement date for identical assets or liabilities. Level 2 securities, consisting of corporate debt, commercial paper, U.S. government agency securities and asset-backed securities, are measured based on other observable inputs, including broker or dealer quotations or alternative pricing sources. When quoted prices in active markets for identical assets or liabilities are not available, we rely on non-binding quotes from our investment managers, which are based on proprietary valuation models of independent pricing services. These models generally use inputs such as observable market data, quoted market prices for similar instruments or historical pricing trends of securities relative to our peers. To validate the fair value determinations provided by our investment managers, we review the pricing movement in the context of overall market trends and trading information from our investment managers. In addition, we assess the inputs and methods used in determining the fair value in order to determine the classification of securities in the fair value hierarchy. We had no Level 3 securities as of March 31, 2023 or December 31, 2022. There were no transfers within the hierarchies during the three months ended March 31, 2023 or the year ended December 31, 2022. T he following tables set forth our financial instruments measured at fair value on a recurring basis by level within the fair value hierarchy at March 31, 2023 and December 31, 2022: March 31, 2023 Fair Value Amortized Gross Gross Fair Assets (in thousands) Cash and cash equivalents: Cash Level 1 $ 38,655 $ — $ — $ 38,655 Money market funds Level 1 82,124 — — 82,124 U.S. Treasury securities Level 1 4,979 — — 4,979 Commercial paper Level 2 254,731 — ( 38 ) 254,693 Total cash and cash equivalents 380,489 — ( 38 ) 380,451 Investments: U.S. Treasury securities Level 1 223,984 218 ( 26 ) 224,176 Commercial paper Level 2 125,074 — ( 10 ) 125,064 Corporate debt Level 2 120,604 11 ( 284 ) 120,331 Asset-backed securities Level 2 21,383 22 - 21,405 U.S. government agency securities Level 2 78,272 193 ( 39 ) 78,426 Total investments 569,317 444 ( 359 ) 569,402 Total assets measured at fair value $ 949,806 $ 444 $ ( 397 ) $ 949,853 December 31, 2022 Fair Value Amortized Gross Gross Fair Assets (in thousands) Cash and cash equivalents: Cash Level 1 $ 56,198 $ — $ — $ 56,198 Money market funds Level 1 680,934 — — 680,934 Commercial paper Level 2 92,581 — ( 34 ) 92,547 U.S. government agency securities Level 2 4,978 — — 4,978 Total cash and cash equivalents 834,691 — ( 34 ) 834,657 Investments: U.S. Treasury securities Level 1 37,651 — ( 70 ) 37,581 Commercial paper Level 2 28,161 — ( 17 ) 28,144 Corporate debt Level 2 25,402 — ( 131 ) 25,271 Asset-backed securities Level 2 6,954 20 — 6,974 U.S. government agency securities Level 2 25,427 19 ( 148 ) 25,298 Total investments 123,595 39 ( 366 ) 123,268 Total assets measured at fair value $ 958,286 $ 39 $ ( 400 ) $ 957,925 The following table presents the contractual maturities of our investments as of March 31, 2023 (in thousands): March 31, 2023 Fair Value Due in less than one year $ 441,587 Due in one to five years 127,815 Total $ 569,402

Balance Sheet Details

Balance Sheet Details	3 Months Ended
	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Details	4. Balance Sheet Details Property and Equipment, Net Property and equipment, net as of March 31, 2023 and December 31, 2022 consisted of the following: March 31, December 31, 2023 2022 (in thousands) Furniture and equipment $ 1,608 $ 1,608 Computers and computer software 416 416 Lab equipment 18,656 13,100 Leasehold improvements 1,353 1,353 Total property and equipment 22,033 16,477 Less: accumulated depreciation and amortization ( 6,828 ) ( 6,117 ) Property and equipment, net $ 15,205 $ 10,360 Depreciation and amortization expense for the three months ended March 31, 2023 and 2022 was $ 0.7 million and $ 0.6 million, respectively. Accrued Expenses Accrued expenses as of March 31, 2023 and December 31, 2022 consisted of the following: March 31, December 31, 2023 2022 (in thousands) Clinical studies $ 1,713 $ 1,518 Other research and development (1) 13,939 12,446 Other accrued expenses 2,699 1,411 Total $ 18,351 $ 15,375 ______________ (1) The balances as of March 31, 2023 and December 31, 2022 include $ 5.0 million of accrued manufacturing rights. See Note 6, “ Commitments and Contingencies, Sutro Option Agreement, ” for further details.

Leases

Leases	3 Months Ended
	Mar. 31, 2023
Leases [Abstract]
Leases	5. Leases Operating Lease Obligations In January 2021, we entered into a lease agreement for our current corporate headquarters facility located in San Carlos, California and a license agreement for temporary lab and office space in Palo Alto, California. The lease term for our current corporate headquarters facility began on December 3, 2021 and expires on December 31, 2025 . We have two 60 -month renewal options. We extended the license agreement for our temporary headquarters in the Palo Alto office by 60 days to March 3, 2022 to accommodate our relocation plan. The original term of the license agreement for the temporary space in Palo Alto terminated when the San Carlos office leasehold improvements were completed and we moved into our current corporate headquarters. These two agreements are accounted for as a combined lease because the contracts were negotiated as a package with the same commercial objective. Upon commencement of the San Carlos lease in December 2021, we recorded a ROU asset and lease liability of $ 28.4 million and $ 12.9 million, respectively. In July 2016, we entered into a five-year lease agreement for our previous headquarters facility located in Foster City, California. The original term of the lease was from September 1, 2016 to August 31, 2021 , with two 30 -month renewal options . In July 2019, we leased another facility in Foster City, California as a result of growth in personnel and lab space requirements. The original term of this lease was from July 1, 2019 to October 31, 2021 , with no renewal options . In November 2020, we extended the terms of both of these leases for six months to March 1, 2022 and April 30, 2022 , respectively. In February 2022, we entered into an early termination agreement for one of the facilities in Foster City and terminated our lease on February 12, 2022 instead of April 30, 2022. Information related to our lease are as follows (dollar amounts in thousands): Three Months Ended March 31, March 31, 2023 2022 Cash paid for operating lease liabilities $ 1,671 $ 621 Weighted-average remaining lease term (in years) 2.54 3.54 Weighted-average discount rate 7.6 % 7.6 % Maturities of lease liabilities as of March 31, 2023 were as follows: Years ending December 31, (in thousands) Remainder of 2023 $ 4,456 2024 6,850 2025 7,022 Thereafter — Total future undiscounted lease payments 18,328 Less: Imputed interest ( 1,743 ) Total lease liabilities $ 16,585 Rent expense recognized under the leases was $ 1.9 million a nd $ 2.2 million for the three months ended March 31, 2023 and 2022 , respectively.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Legal Contingencies From time to time, we may become involved in legal proceedings arising from the ordinary course of business. We record a liability for such matters when it is probable that future losses will be incurred and that such losses can be reasonably estimated. Significant judgment by us is required to determine both probability and the estimated amount. We do not believe that there is any litigation or asserted or unasserted claim pending that could, individually or in the aggregate, have a material adverse effect on our results of operations or financial condition. Guarantees and Indemnifications In the normal course of business, we enter into agreements that contain a variety of representations and provide for general indemnification. Our exposure under these agreements is unknown because it involves claims that may be made against us in the future. To date, we have not paid any claims or been required to defend any action related to our indemnification obligations. As of March 31, 2023, we did not have any material indemnification claims that were probable or reasonably possible and consequently have not recorded related liabilities. Indemnification To the extent permitted under Delaware law, we have agreed to indemnify our directors and officers for certain events or occurrences while the director or officer is, or was, serving at our request in such capacity. The indemnification period covers all pertinent events and occurrences during the director’s or officer’s service. The maximum potential amount of future payments we could be required to make under these indemnification agreements is not specified in the agreements; however, we have director and officer insurance coverage that reduces our exposure and enables us to recover a portion of any future amounts paid. We have not incurred any material costs as a result of such indemnification and are not currently aware of any indemnification claims. Development and Manufacturing Services Agreement In October 2016, we entered into a non-exclusive development and manufacturing services agreement, as amended, with Lonza (the “2016 Lonza DMSA”) pursuant to which Lonza was obligated to perform manufacturing process development and the manufacture of components for VAX-24, including the polysaccharide antigens, our proprietary eCRM protein carrier and conjugated drug substances. Subject to the terms and conditions set forth in the 2016 Lonza DMSA, Lonza granted to us a non-exclusive, worldwide, fully paid-up, irrevocable, transferable license, including the right to grant sublicenses, under the New General Application Intellectual Property, to research, develop, make, have made, use, sell and import the Product manufactured under the 2016 Lonza DMSA (each term as defined in the 2016 Lonza DMSA). The term of the 2016 Lonza DMSA expired on March 31, 2023. In September 2017, we and Lonza agreed to defer the completion payments for any stage that commenced after December 31, 2019 or had not been completed by December 31, 2019 until the earlier of the completion of all Investigational New Drug (“IND”)-enabling activities or December 31, 2020. In March 2020, Lonza agreed to defer the completion payments until the earlier of the completion of all IND-enabling activities or April 30, 2021. In April 2021, Lonza further agreed to defer 50 % of the completion payments until the earlier of the completion of all IND-enabling activities or December 31, 2021. Pursuant to this agreement, all deferred completion payments were paid in December 2021. In June 2018, we entered into a letter agreement with Lonza (the “Lonza Letter Agreement”) pursuant to which we agreed to certain terms for potential future payments in shares of our common stock as partial satisfaction of future obligations to Lonza. The Lonza Letter Agreement stated that the initial pre-IND cash payments under the 2016 Lonza DMSA were subject to a specified dollar cap (the “Initial Cash Cap”). After the Initial Cash Cap was reached, we had the option to make any further pre-IND payments owed to Lonza in cash, in shares of our common stock at then market prevailing prices, or a combination of both, at our election. In April 2021, we reached the Initial Cash Cap and notified Lonza that we would be exercising our option to issue approximately $ 10.0 million in shares of our common stock as payment for a portion of pre-IND payments due April 30, 2021. In June 2021, we issued 399,680 shares of our common stock to Lonza at a price of $ 25.02 per share to pay for $ 10.0 million of the pre-IND payments due April 30, 2021. In October 2018, we entered into a second non-exclusive development and manufacturing services agreement with Lonza (the “2018 Lonza DMSA”), pursuant to which Lonza is obligated to perform services including manufacturing process development and the manufacture and supply of VAX-24 finished drug product. Subject to the terms and conditions set forth in the 2018 Lonza DMSA, Lonza has granted to us a non-exclusive, worldwide, fully paid-up, irrevocable, transferable license, including the right to grant sublicenses, under the New General Application Intellectual Property, to research, develop, make, have made, use, sell and import the Product (each term as defined in the 2018 Lonza DMSA). Unless earlier terminated, the 2018 Lonza DMSA will remain in place for a period of five years. Either party has the right to terminate the 2018 Lonza DMSA upon a six-month notice period, provided that Lonza may not exercise such right until a specified future date. Either party has the right to terminate the 2018 Lonza DMSA if the other party commits a material breach under the applicable agreement and does not cure such breach within a given time period, for specified bankruptcy events or if a party receives a notice from the other party or otherwise becomes aware that a debarment, suspension, exclusion, sanction or declaration of ineligibility action has been brought against the other party, and we may terminate the 2018 Lonza DMSA for an extended force majeure event. In April 2022, we entered into a third non-exclusive development and manufacturing services agreement, as amended, with Lonza (the “2022 Lonza DMSA”) effective as of March 22, 2022. Pursuant to the 2022 Lonza DMSA, Lonza is obligated to perform services including manufacturing process development and clinical manufacture and supply of our proprietary pneumococcal conjugate vaccine (“PCV”) candidates. Subject to the terms and conditions set forth in the 2022 Lonza DMSA, Lonza has granted to us a non-exclusive, worldwide, fully paid-up, irrevocable, transferable license, including the right to grant sublicenses, under the New General Application Intellectual Property, to research, develop, make, have made, use, sell and import the Product. Unless earlier terminated, the 2022 Lonza DMSA shall remain in place for a period of five years. Either party may terminate the 2022 Lonza DMSA for any reason on prior written notice to the other party, provided that Lonza may not exercise such right until a specified future date. In addition, either party may terminate the 2022 Lonza DMSA (i) within a given time period upon any material breach that is left uncured by the other party, or (ii) immediately if the other party becomes insolvent. We may also terminate the 2022 Lonza DMSA upon an extended force majeure event. Upon expiration and/or termination of the 2022 Lonza DMSA and/or any purchase order, we will pay Lonza for all service rendered, all costs incurred, all unreimbursed capital equipment and any cancellation fees (each term as defined in the 2022 Lonza DMSA). In February 2023, we entered into a fourth non-exclusive development and manufacturing services agreement with Lonza (the “2023 Lonza DMSA”) effective as of March 1, 2023. Pursuant to the 2023 Lonza DMSA, Lonza will perform manufacturing process development and the manufacture of components for VAX-24 and VAX-31, including the polysaccharide antigens, our proprietary eCRM protein carrier and conjugated drug substances. Subject to the terms and conditions set forth in the 2023 Lonza DMSA, Lonza has granted to us a non-exclusive, worldwide, fully paid-up, transferable license, including the right to grant sublicenses (subject to the prior written consent of Lonza), under the New General Application Intellectual Property, to use, sell and import the Product manufactured under the 2023 Lonza DMSA (but no other products). Unless earlier terminated, the 2023 Lonza DMSA shall remain in place for a period of five years and shall automatically renew for one additional two-year period unless either party provides written notice of non-renewal at least two years prior to the fifth anniversary of the effective date. We may terminate the 2023 Lonza DMSA for any reason on prior written notice to the other party on a Project Plan-by-Project Plan basis. Either party may terminate the 2023 Lonza DMSA (i) within a given time period upon any material breach that is left uncured by the other party, (ii) immediately if the other party becomes insolvent, is dissolved or liquidated, makes a general assignment for the benefit of its creditors, or files or has filed against it, a petition in bankruptcy or has a receiver appointed for a substantial part of its assets, (iii) upon an extended force majeure event, or (iv) if it becomes apparent to either party at any stage in the provision of the Services that it will be impossible to complete the Services for scientific or technical reasons despite exercise of best commercial efforts by both parties. Pursuant to the reason for termination and the party initiating the termination, we will pay Lonza for some combination of services rendered, costs incurred, unreimbursed capital equipment and/or any cancellation fees. Upon an extended force majeure event, neither party shall have any further liability to the other party (each term as defined in the 2023 Lonza DMSA). Under each of the 2016 Lonza DMSA, 2018 Lonza DMSA, 2022 Lonza DMSA and 2023 Lonza DMSA (collectively, the “Lonza Agreements”), we pay Lonza agreed-upon fees for their performance of development and manufacturing services and pass through expenses incurred by Lonza for raw materials, as well as customary procurement and handling fees. Under each Lonza Agreement, we own all right, title and interest in and to any and all New Customer Intellectual Property (as defined in each Lonza Agreement), and Lonza owns all right, title and interest in New General Application Intellectual Property (as defined in each Lonza Agreement). Sutro Option Agreement In December 2022, we entered into an Option Agreement with Sutro Biopharma, pursuant to which we acquired from Sutro Biopharma (i) authorization to enter into an agreement with an independent alternate CMO to directly source Sutro Biopharma’s cell-free extract, allowing us to have direct oversight over financial and operational aspects of the relationship with the CMO; and (ii) a right, but not an obligation, to obtain certain exclusive rights to internally manufacture and/or source extract from certain CMOs and the right to independently develop and make improvements to extract (including the right to make improvements to the extract manufacturing process as well as cell lines) for use in connection with the exploitation of certain vaccine compositions (the “Option”). We and Sutro Biopharma have agreed to negotiate the terms and conditions of a form definitive agreement to be entered into in the event we exercise the Option, which shall include the terms and conditions set forth in an executed term sheet between us (the “Term Sheet”), and such terms that are necessary to give effect to each of the terms and conditions set forth in the Term Sheet (the “Form Definitive Agreement”). The Option period is five years from the date of the Option Agreement, subject to potential acceleration in the event we undergo a change of control. As consideration for the Option and other rights and authorizations granted to us under the Option Agreement, we agreed to pay Sutro Biopharma upfront consideration of $ 22.5 million, consisting of (i) $ 10.0 million in cash and $ 7.5 million worth of shares of our common stock (the number of shares to be calculated based on the arithmetic average of the daily volume weighted average price of our common stock as traded on Nasdaq in the three consecutive trading days immediately prior to the issuance thereof), and (ii) $ 5.0 million payable within five business days after we and Sutro Biopharma mutually agree in writing upon the Form Definitive Agreement. The 167,780 shares of common stock issued was recorded at fair value of $ 8.0 million on the date of settlement, December 22, 2022. In the event that we elect to exercise the Option, we would pay Sutro Biopharma an aggregate Option exercise price of $ 75.0 million in cash in two installments and, upon the occurrence of certain regulatory milestones, certain additional milestone payments totaling up to $ 60.0 million in cash. In the event that we undergo a change of control, certain rights and payments may be accelerated. We determined there is no current alternative future use of the acquired manufacturing rights from the Sutro Option Agreement. As a result, the amounts paid and accrued for were expensed as incurred. As of March 31, 2023 and December 31, 2022, the $ 5.0 million accrued commitment remains outstanding and is included in accrued expenses in the accompanying condensed balance sheet. Purchase Commitments We enter into agreements in the normal course of business with CMOs and other vendors for manufacturing services and raw materials purchases. We rely on several third-party manufacturers for our manufacturing requirements. As of March 31, 2023, we had the following amounts due of non-cancelable purchase commitments related to manufacturing services and raw materials purchased due to our key manufacturing partners. These amounts represent our minimum contractual obligations, including termination fees. If we terminate certain firm orders with key manufacturing partners, we will be required to pay for the manufacturing services scheduled or raw materials purchased under our arrangements. The actual amounts we pay in the future to our vendors under such agreements may differ from the purchase order amounts. Years ending December 31, (in thousands) Remainder of 2023 $ 97,648 2024 47,478 Total non-cancelable purchase commitments due to our key manufacturing partners $ 145,126

Common Stock

Common Stock	3 Months Ended
	Mar. 31, 2023
Equity [Abstract]
Common Stock	7. Common Stock Our certificate of incorporation authorizes us to issue up to 500,000,000 shares of common stock with $ 0.001 par value per share, of which 80,640,851 and 79,470,670 shares were issued and outstanding as of March 31, 2023 and December 31, 2022, respectively. The holders of our common stock are also entitled to receive dividends whenever funds are legally available, when and if declared by our board of directors. As of March 31, 2023 and December 31, 2022 , no dividends had been declared. Each share of common stock is entitled to one vote. In July 2021, we entered into an Open Market Sales Agreement SM (the “Original ATM Sales Agreement”) with Jefferies LLC (“Jefferies”), which provided that, upon the terms and subject to the conditions and limitations set forth in the Original ATM Sales Agreement, we may elect to issue and sell, from time to time, shares of our common stock having an aggregate offering price of up to $ 150.0 million through Jefferies acting as our sales agent or principal. As of February 27, 2023, we had sold 4,995,709 shares of our common stock under the Original ATM Sales Agreement at an average price of $ 27.57 per share for aggregate gross proceeds of $ 137.8 million. On February 27, 2023, we and Jefferies entered into an amendment to the Original ATM Sales Agreement (as amended, the “Amended ATM Sales Agreement”) pursuant to which we may offer and sell shares of our common stock having an aggregate offering price of up to $ 400.0 million, which is in addition to the $ 150.0 million aggregate offering price under the Original ATM Sales Agreement. The material terms and conditions of the Original ATM Sales Agreement otherwise remain unchanged. We will pay Jefferies a commission of up to 3.0 % of the gross sales proceeds of any common stock sold through Jefferies under the Amended ATM Sales Agreement; however, we are not obligated to make any sales of common stock. As of March 31, 2023, we have sold 534,400 shares of our common stock under the Amended ATM Sales Agreement at an average price of $ 37.42 per share for aggregate gross proceeds of $ 20.0 million ($ 19.6 million net of commissions and offering expenses). On January 13, 2022, we completed an underwritten public offering in which we issued 2,500,000 shares of our common stock at a price of $ 20.00 per share and pre-funded warrants to purchase 2,500,000 shares of our common stock at a price of $ 19.999 per underlying share. In February 2022, the underwriters exercised their option to purchase an additional 750,000 shares of common stock. In aggregate, we received approximately $ 107.6 million in net proceeds after deducting underwriting discounts and commissions and other offering expenses payable by us, and excluding the exercise of any pre-funded warrants. On October 28, 2022, we completed an underwritten public offering of 17,812,500 shares of our common stock, which included the full exercise of the underwriters’ option to purchase an additional 2,812,500 shares, at a price of $ 32.00 per share and pre-funded warrants to purchase 3,750,000 shares of our common stock at a price of $ 31.999 per underlying share. In aggregate, we received $ 651.6 million in net proceeds after deducting underwriting discounts and commissions and other offering expenses payable by us, and excluding the exercise of any pre-funded warrants. Common stock reserved for future issuance under the 2020 Equity Incentive Plan (the “2020 Plan”) and the 2014 Equity Incentive Plan (the “2014 Plan”) was as follows, and excludes 36,710 shares issued outside of the 2014 Plan and 2020 Plan: March 31, December 31, 2023 2022 Options issued and outstanding 9,147,034 7,715,494 Restricted stock units outstanding 773,660 456,766 Shares available for future stock option grants 6,776,052 4,679,598 Total 16,696,746 12,851,858 Refer to Note 14, “Subsequent Events” for details of our underwritten public offering that was closed subsequent to March 31, 2023.

Pre-Funded Warrants

Pre-Funded Warrants	3 Months Ended
	Mar. 31, 2023
Equity [Abstract]
Pre-Funded Warrants	8. P re-Funded Warrants In connection with our underwritten public offering in January 2022, we issued 3,250,000 shares of our common stock at a price of $ 20.00 per share and pre-funded warrants to purchase 2,500,000 shares of our common stock at a price of $ 19.999 per underlying share. Each pre-funded warrant has an exercise price of $ 0.001 per share. In connection with our underwritten public offering in October 2022, we issued 17,812,500 shares of our common stock at a price of $ 32.00 per share and pre-funded warrants to purchase 3,750,000 shares of our common stock at a price of $ 31.999 per underlying share. Each pre-funded warrant has an exercise price of $ 0.001 per share. The public offering price for the pre-funded warrants were equal to the public offering price of our common stock, less the $ 0.001 exercise price of each pre-funded warrant and were recorded as a component of stockholders' equity within additional paid-in-capital. The pre-funded warrants are exercisable, at the option of each holder, in whole or in part by delivering to us a duly executed exercise notice and payment of the exercise price. No fractional shares of common stock will be issued in connection with the exercise of a pre-funded warrant. The holders of the pre-funded warrants may also satisfy their obligation to pay the exercise price through a “cashless exercise,” in which the holder receives the net value of the pre-funded warrant in shares of common stock determined according to the formula set forth in the pre-funded warrant. The pre-funded warrants will not expire until they are fully exercised. However, we may not effect the exercise of any pre-funded warrants, and a holder will not be entitled to exercise any portion of any pre-funded warrants that, upon giving effect to such exercise, would cause: (i) the aggregate number of shares of our common stock beneficially owned by such holder (together with affiliates) to exceed 4.99 % or 9.99 % of the number of shares of our common stock outstanding immediately after giving effect to the exercise, as applicable; or (ii) the combined voting power of our securities beneficially owned by such holder (together with its affiliates) to exceed 4.99 % or 9.99 % of the combined voting power of all of our securities outstanding immediately after giving effect to the exercise, as applicable, as such percentage ownership is determined in accordance with the terms of the pre-funded warrants. However, any holder of a pre-funded warrant may increase or decrease such percentage to any other percentage not in excess of 19.99 % upon at least 61 days' prior notice for the holder to us. As of March 31, 2023 , no shares underlying the pre-funded warrants had been exercised. Refer to Note 14, “Subsequent Events” for details of our underwritten public offering that was closed subsequent to March 31, 2023.

Equity Incentive Plans

Equity Incentive Plans	3 Months Ended
	Mar. 31, 2023
Share-Based Payment Arrangement [Abstract]
Equity Incentive Plans	9. Equity Incentive Plans 2020 and 2014 Equity Incentive Plans In June 2020, our board of directors adopted, and our stockholders approved, the 2020 Plan, which became effective on June 11, 2020. Under the 2020 Plan, we may grant stock options, appreciation rights, restricted stock and restricted stock units (“RSUs”) to employees, consultants and directors. Stock options granted under the 2020 Plan may be either incentive stock options or nonqualified stock options. Incentive stock options may be granted only to our employees, including officers and directors who are also employees. Nonqualified stock options may be granted to our employees, officers, directors, consultants and advisors. The exercise price of stock options granted under the 2020 Plan must be at least equal to the fair market value of the common stock on the date of grant, except that an incentive stock option granted to an employee who owns more than 10 % of the shares of our common stock shall have an exercise price of no less than 110 % of the fair value per share on the grant date and expire five years from the date of grant. The maximum term of stock options granted under the 2020 Plan is 10 years, unless subject to the provisions regarding 10 % stockholders. Our stock options granted to new employees generally vest over four years at a rate of 25 % upon the first anniversary of the vesting commencement date and monthly thereafter. Our other stock options granted to employees generally vest on terms consistent with stock options granted to new employees or monthly over four years from the vesting commencement date. Our RSUs granted to new employees generally vest over four years at a rate of 25 % upon one year from the grant date, then 12.5 % every six months thereafter. Our other RSUs granted to employees generally vest over three and a half years at a rate of 25 % upon six months from the grant date, then 12.5 % every six months thereafter. A total of 10,150,000 shares of common stock were approved to be initially reserved for issuance under the 2020 Plan. The number of shares that remained available for issuance under the 2014 Plan as of the effective date of the 2020 Plan and shares subject to outstanding awards under the 2014 Plan as of the effective date of the 2020 Plan that are subsequently canceled, forfeited or repurchased by us will be added to the shares reserved under the 2020 Plan. In addition, the number of shares of common stock available for issuance under the 2020 Plan will be automatically increased on the first day of each calendar year during the ten-year term of the 2020 Plan, beginning with January 1, 2021 and ending with January 1, 2030, by an amount equal to 5 % of the outstanding number of shares of our common stock on December 31 of the preceding calendar year or such lesser amount as determined by our board of directors. Effective January 1, 2023, the number of shares of common stock available under the 2020 Plan increased by 3,973,533 shares pursuant to the evergreen provision. As of March 31, 2023, an aggregate of 6,776,052 shares of common stock were available for issuance under the 2020 Plan. Our 2014 Plan permitted the granting of incentive stock options, non-statutory stock options, restricted stock and other stock-based awards. Subsequent to the adoption of the 2020 Plan, no additional equity awards can be made under the 2014 Plan. As of March 31, 2023, 2,488,567 shares and 7,432,127 shares of common stock were subject to outstanding options and RSUs under the 2014 Plan and 2020 Plan, respectively. The terms of the 2014 Plan permit the exercise of options granted prior to vesting, subject to required approvals. The unvested shares are subject to our lapsing repurchase right upon termination of employment at the original purchase price. Shares purchased by employees pursuant to the early exercise of stock options are not deemed, for accounting purposes, to be issued until those shares vest according to their respective vesting schedules. Cash received for early exercised stock options is recorded as other liabilities on the condensed balance sheet and is reclassified to common stock and additional paid-in capital as such shares vest. At March 31, 2023 and December 31, 2022, 2,779 and 3,705 shares, respectively, remained subject to our right of repurchase as a result of the early exercised stock options. The remaining liabilities related to early exercised shares as of March 31, 2023 and December 31, 2022 were both less than $ 0.1 million and were recorded in other liabilities. Stock Options and Restricted Stock Units Activity Stock options and RSUs activity under our 2020 Plan and 2014 Plan, which excludes options to purchase 36,710 shares granted outside of the 2020 Plan and 2014 Plan, was as follows: Options Outstanding Stock Options and Restricted Stock Units Activity Options and Number Weighted- Weighted- Aggregate Balances — December 31, 2022 4,679,598 7,715,494 $ 18.70 Additional shares authorized 3,973,533 Options granted ( 1,574,642 ) 1,574,642 $ 41.84 Options exercised 1,080 (1) ( 102,044 ) $ 5.40 Options forfeited 41,058 ( 41,058 ) $ 31.95 Restricted stock units granted ( 374,458 ) Restricted stock units withheld 17,525 Restricted stock units forfeited 12,358 Balances — March 31, 2023 6,776,052 9,147,034 $ 22.77 8.32 $ 146,986 Vested and expected to vest — March 31, 2023 9,147,034 $ 22.77 8.32 $ 146,986 Exercisable at March 31, 2023 3,242,028 $ 10.88 6.85 $ 86,670 (1) Net exercise – shares returned to the Plan. During the three months ended March 31, 2023 and 2022, 100,964 and 91,044 shares of stock options, respectively, were exercised for cash at a weighted-average price per share of $ 5.40 and $ 3.18 , respectively. The weighted-average grant date fair value of options granted for the three months ended March 31, 2023 and 2022 was $ 27.18 and $ 16.34 , respectively. The intrinsic value of the stock options exercised was $ 3.8 million and $ 1.8 million for the three months ended March 31, 2023 and 2022, respectively. In March 2022, our board of directors authorized the issuance of RSUs under our 2020 Plan and adopted a form of Restricted Stock Unit Grant Notice and Restricted Stock Unit Award Agreement (the “RSU Agreement”), which is intended to serve as a standard form agreement for RSU grants issued to employees. RSU activity for the three months ended March 31, 2023 was as follows: Shares Weighted- Unvested at December 31, 2022 456,766 $ 26.70 Granted 374,458 41.59 Vested and released ( 45,206 ) 24.58 Cancelled ( 12,358 ) 33.67 Unvested at March 31, 2023 773,660 $ 33.92 The weighted-average grant date fair value of RSUs granted during the three months ended March 31, 2023 and 2022 was $ 41.59 and $ 24.67 , respectively. The aggregate fair value of unvested RSU is calculated using the closing price of our common stock on the grant date. As of March 31, 2023 , the unrecognized stock-based compensation cost of unvested RSUs was $ 24.4 million, which is expected to be recognized over a weighted-average period of 3.1 years. 2020 Employee Stock Purchase Plan In June 2020, our board of directors adopted, and our stockholders approved, the 2020 Employee Stock Purchase Plan (the “2020 ESPP”), which became effective on June 11, 2020. The 2020 ESPP permits participants to purchase common stock through payroll deductions of up to 15 % of their eligible compensation. Employees enrolled in the 2020 ESPP purchase shares of common stock at a price per share equal to 85 % of the lower of the fair market value at the start or end of the six-month purchase periods within the two-year offering period. A total of 650,000 shares of common stock were approved to be initially reserved for issuance under the 2020 ESPP. In addition, the number of shares of common stock available for issuance under the 2020 ESPP will be automatically increased on the first day of each calendar year during the ten-year term of the 2020 Plan, beginning with January 1, 2021 and ending with January 1, 2030, by an amount of 1 % of the outstanding number of shares of our common stock on December 31 of the preceding calendar year or such lesser amount as determined by our board of directors. Activity under our 2020 ESPP was as follows: Shares Balance - December 31, 2021 1,070,704 Additional shares authorized 530,319 Shares purchased ( 61,709 ) Balance - December 31, 2022 1,539,314 Additional shares authorized 794,706 Shares purchased — Balance - March 31, 2023 2,334,020 Effective January 1, 2023, the number of shares of common stock available under the 2020 ESPP increased by 794,706 shares pursuant to the evergreen provision of the 2020 ESPP. Stock-based Compensation We estimated the fair value of employee stock options using the Black-Scholes option-pricing model for the three months ended March 31, 2023 and 2022 using the following weighted-average assumptions: Three Months Ended March 31, 2023 2022 Fair Value Assumptions Expected volatility 73.6 % - 74.0 % 78.1 % - 78.9 % Expected dividend yield 0 % 0 % Expected term (in years) 5.3 - 5.4 5.4 Risk-free interest rate 3.7 % - 4.3 % 1.6 % - 2.4 % We estimated the fair value of shares under the 2020 ESPP using the Black-Scholes option-pricing model for the three months ended March 31, 2023 and 2022 using the following weighted-average assumptions: Three Months Ended March 31, 2023 2022 Fair Value Assumptions Expected volatility 86.4 % - 99.7 % 86.7 % - 97.5 % Expected dividend yield 0 % 0 % Expected term (in years) 0.5 - 2.0 0.5 - 2.0 Risk-free interest rate 4.5 % - 4.7 % 0.1 % - 0.5 % We recorded total stock-based compensation expense for the three months ended March 31, 2023 and 2022 related to the 2014 Plan, the 2020 Plan and the 2020 ESPP in the condensed statements of operations and allocated the amounts as follows: Three Months Ended March 31, 2023 2022 (in thousands) Research and development $ 4,527 $ 1,775 General and administrative 5,121 2,324 Total $ 9,648 $ 4,099

Retirement Plan

Retirement Plan	3 Months Ended
	Mar. 31, 2023
Retirement Benefits [Abstract]
Retirement Plan	10. Retirement Plan We sponsor a qualified 401(k) Plan. The 401(k) Plan is a defined contribution plan covering eligible employees. Participants may contribute a portion of their annual compensation limited to a maximum annual amount set by the Internal Revenue Service. For the three months ended March 31, 2023 and 2022, the Company contributed $ 0.4 million and $ 0.2 million, respectively, to the retirement plan.

Funding Arrangement

Funding Arrangement	3 Months Ended
	Mar. 31, 2023
Funding Arrangement [Abstract]
Funding Arrangement	11. Funding Arrangement In July 2019, we received a cost-reimbursement research award from Combating Antibiotic Resistant Bacteria Biopharmaceutical Accelerator (“CARB-X”), a public-private partnership funded under a Cooperative Agreement from Assistant Secretary for Preparedness and Response/Biomedical Advanced Research and Development Authority (“BARDA”) and by awards from Wellcome Trust, Germany’s Federal Ministry of Education and Research, the United Kingdom Global Antimicrobial Resistance Innovation Fund and the Bill & Melinda Gates Foundation. In connection with this funding, we entered into a cost-reimbursement sub-award agreement with the Trustees of Boston University, the administrator of the program. The initial award provided the potential for funding up to four years to develop a universal vaccine to prevent infections caused by Group A Strep bacteria, which include pharyngitis, impetigo and necrotizing fasciitis. The initial award committed initial funding of up to $ 1.6 million for our VAX-A1 program and, subject to a CARB-X decision to extend the options, up to $ 15.1 million in total funding available upon achievement of development milestones over the next four years . Specified research expenditures are reimbursable expenses associated with agreed-upon activities needed to advance the research project supported by the grant. These expenditures can include labor, laboratory supplies, travel, consulting and third-party vendor research and development support costs. CARB-X has awarded us total funding to date of $ 11.7 million, with potential funding of up to $ 14.6 million upon the achievement of future VAX-A1 development milestones. In April 2021, we received a cost-reimbursement research award from the National Institutes of Health (“NIH”). In connection with this funding, we entered into a cost-reimbursement sub-award agreement with the University of Maryland, Baltimore, the administrator of the program. The award provides for potential funding up to five years totaling approximately $ 0.5 million to develop a vaccine to prevent infections caused by Shigella. Income from grants is recognized in the period during which the related specified expenses are incurred, provided that the conditions under which the grants were provided have been met. We recognized $ 0.7 million and $ 0.2 million of grant income under the CARB-X and Shigella awards and recorded the amounts in Other income (expense), net in the condensed statement of operations during the three months ended March 31, 2023 and 2022, respectively. A grant receivable of $ 1.3 million and $ 1.0 million representing unreimbursed, eligible costs incurred under the CARB-X and Shigella agreements was recorded and included in Prepaid expenses and other current assets in the condensed balance sheets as of March 31, 2023 and December 31, 2022 , respectively.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2023
Earnings Per Share [Abstract]
Net Loss Per Share	12. Net Loss Per Share The following table sets forth the computation of basic and diluted net loss per share and excludes shares which are legally outstanding, but subject to repurchase by us: Three Months Ended 2023 2022 Net loss (in thousands) $ ( 60,462 ) $ ( 38,986 ) Weighted-average shares outstanding used in computing net (1) 86,206,817 57,547,808 Net loss per share, basic and diluted $ ( 0.70 ) $ ( 0.68 ) (1) Includes shares of common stock into which pre-funded warrants may be exercised as of March 31, 2023 and does not include any pre-funded warrants issued subsequent to that date. See Note 8 - Pre-Funded Warrants. The following p otentially dilutive securities outstanding as of the periods presented below were excluded from the computation of diluted net loss per share for the three months ended March 31, 2023 because including them would have been antidilutive: As of March 31, 2023 2022 Stock options 9,183,744 6,859,801 Restricted stock units 773,660 373,441 Employee stock purchase plan shares 117,203 — Total 10,074,607 7,233,242

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	13. Income Taxes In determining quarterly provisions for income taxes, we use the annual estimated effective tax rate applied to the actual year-to-date profit or loss, adjusted for discrete items arising in that period. Our annual estimated effective tax rate differs from the U.S. federal statutory rate primarily as a result of state taxes and changes in our valuation allowance against our deferred tax assets. For all periods presented, we have incurred net pre-tax losses in the United States. During the three months ended March 31, 2023, there were no material changes to our unrecognized tax benefits, and we do not expect to have any significant changes to unrecognized tax benefits through the end of the fiscal year. For the three months ended March 31, 2023 , we reported zero tax provision. We do not have any tax audits or other issues pending.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2023
Disclosure Text Block [Abstract]
Subsequent Events	14. Subsequent Events On April 21, 2023, we completed an underwritten public offering of 13,030,000 shares of our common stock, which included the full exercise of the underwriters ’ option to purchase an additional 1,830,000 shares, at a price of $ 41.00 per share and pre-funded warrants to purchase 1,000,000 shares of our common stock at a price of $ 40.999 per underlying share. In aggregate, we received $ 545.1 million in net proceeds after deducting underwriting discounts and commissions and other estimated offering expenses payable by us, and excluding the exercise of any pre-funded warrants.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation These condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP, and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and footnote disclosures normally included in the financial statements prepared in accordance with U.S. GAAP have been condensed or omitted in accordance with such rules and regulations.
Unaudited Interim Condensed Financial Statements	Unaudited Interim Condensed Financial Statements The condensed balance sheet as of March 31, 2023, the condensed statements of operations, comprehensive loss and stockholders’ equity for the three months ended March 31, 2023 and 2022 and the condensed statements of cash flows for the three months ended March 31, 2023 and 2022 are unaudited. The unaudited interim condensed financial statements have been prepared on the same basis as the audited annual financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair statement of our financial information. The financial data disclosed in the footnotes to the condensed financial statements related to the three months ended March 31, 2023 and 2022 are also unaudited. The results of operations for the three months ended March 31, 2023 are not necessarily indicative of the results to be expected for the year ending December 31, 2023 or for any other future annual or interim period. These interim condensed financial statements should be read in conjunction with our audited financial statements and related notes thereto for the year ended December 31, 2022 included in our Annual Report on Form 10-K filed with the SEC on February 27, 2023.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and expenses and the disclosure of contingent assets and liabilities at the date of the financial statements. On an ongoing basis, we evaluate our estimates and assumptions, including those related to stock-based compensation expense, accruals for certain research and development costs, the valuation of deferred tax assets and income taxes. Management bases our estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ materially from those estimates.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash We consider all highly liquid investments purchased with original maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents consist primarily of amounts invested in money market funds and commercial paper and are stated at their fair values. Restricted cash consists of a standby letter of credit, which was issued in the first quarter of 2021, that serves as collateral for the lease agreement for our current corporate headquarters. Cash, cash equivalents and restricted cash as reported within the condensed balance sheets that total to the same amounts shown in the condensed statement of cash flows are as follows: March 31, December 31, 2023 2022 (in thousands) Cash and cash equivalents $ 380,451 $ 834,657 Restricted cash 871 871 Cash, cash equivalents and restricted cash $ 381,322 $ 835,528
Investments	Investments Our investments have been classified and accounted for as available-for-sale securities. Fixed income securities consist of U.S. Treasury securities, U.S. government agency securities, corporate debt, commercial paper and asset-backed securities. These securities are recorded on the condensed balance sheets at fair value. Unrealized gains and losses on these securities are included as a separate component of accumulated other comprehensive gain (loss). The cost of investment securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in other income (expense), net. Realized gains and losses are also included in other income (expense), net. When the fair value of a debt security declines below its amortized cost basis, any portion of that decline attributable to credit losses, to the extent expected to be nonrecoverable before the sale of the security, is recognized in our condensed statements of operations. When the fair value of a debt security declines below its amortized cost basis due to changes in interest rates, such amounts are recorded in other comprehensive loss, and are recognized in our condensed statements of operations only if we sell or intend to sell the security before recovery of its cost basis.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted average of shares of common stock outstanding, including pre-funded warrants issued, during the period, without consideration for common stock equivalents. Shares of common stock into which the pre-funded warrants may be exercised are considered outstanding for the purposes of computing net loss per share because the shares may be issued for little consideration, are fully vested and are exercisable after the original issuance date. Diluted net loss per share is the same as basic net loss per share since the effects of potentially dilutive securities are antidilutive given the net loss for each period presented.
Leases	Leases We determine if an arrangement is a lease at inception. In addition, we determine whether a lease meets the classification criteria of a finance or operating lease at the lease commencement date considering whether: (i) the lease transfers ownership of the underlying asset to the lessee at the end of the lease term; (ii) the lease grants the lessee an option to purchase the underlying asset that the lessee is reasonably certain to exercise; (iii) the lease term is for a major part of the remaining economic life of the underlying asset; (iv) the present value of the sum of the lease payments and residual value guaranteed by the lessee equals or exceeds substantially all of the fair value of the underlying asset; and (v) the underlying asset is such a specialized nature that it is expected to have no alternative use to the lessor at the end of the lease term. As of March 31, 2023, our lease population consisted of office operating leases. As of March 31, 2023 , we did no t have finance leases. Operating leases are included in Operating lease right-of-use (“ROU”) assets, Operating lease liabilities — current and Operating lease liabilities — long term in our condensed balance sheet. ROU assets represent our right to use the underlying assets for the lease term and lease liabilities represent our obligation to make lease payments arising from the leases. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the present value of lease payments, if the rate implicit in the lease is not readily determinable, we use our incremental borrowing rate based on the information available at the lease commencement date. We determine the incremental borrowing rate based on an analysis of corporate bond yields with a credit rating similar to ours. The determination of our incremental borrowing rate requires management judgment, including development of a synthetic credit rating and cost of debt, as we currently do not carry any debt. We believe that the estimates used in determining the incremental borrowing rate are reasonable based upon current facts and circumstances. Applying different judgment to the same facts and circumstances could yield a different incremental borrowing rate. The operating lease ROU assets also include adjustments for prepayments and accrued lease payments and exclude lease incentives. ROU assets and lease liabilities may include options to extend or terminate leases if it is reasonably certain that we will exercise such options. Lease payments which are fixed and determinable are amortized as rent and lease expense on a straight-line basis over the expected lease term. Variable lease costs, which are dependent on usage, a rate or index, including common area maintenance charges, are expensed as incurred. Lease agreements that include lease and non-lease components are accounted for as a single lease component. Lease agreements with non-cancelable terms of less than 12 months are not recorded on our condensed balance sheets.
Concentration of Credit Risk and Other Risks and Uncertainties	Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject us to a concentration of credit risk consist primarily of cash, cash equivalents and investments. We invest in money market funds, U.S. Treasury securities, U.S. government agency securities, corporate debt, commercial paper and asset-backed securities. We maintain bank deposits in federally insured financial institutions and these deposits may exceed federally-insured limits. We are exposed to credit risk in the event of a default by the financial institutions holding our cash and issuers of investments to the extent recorded on the condensed balance sheets. For example, on March 10, 2023, the California Department of Financial Protection and Innovation took control of Silicon Valley Bank (“SVB”) and appointed the Federal Deposit Insurance Corporation (“FDIC”) as receiver. While SVB was our primary bank at the time, we maintained banking relationships with other major banks. The substantial majority of funds we held at SVB, which included cash, cash equivalents and investments were held in custodial accounts of a third-party institution for which SVB Asset Management was the advisor (“SVB Custodial Accounts”). On March 12, 2023, the FDIC confirmed that depositors of SVB would have access to all of their money and, as a result, we regained access to all of our funds deposited with SVB. The FDIC subsequently transferred SVB’s deposits and loans to a newly created bridge bank, named Silicon Valley Bridge Bank, N.A. (“Silicon Valley Bridge Bank”). On March 26, 2023, the FDIC announced that First Citizens Bank & Trust Company (“First Citizens Bank”) had agreed to purchase and assume all deposits and loans of Silicon Valley Bridge Bank. Management believes that we are not exposed to significant credit risk as our deposits are held at First Citizens Bank, and our investments are held under separate financial institution custodial accounts, each of which management continues to believe to be of high credit quality. We have not experienced any losses on these deposits or investments as a result of this market event. While we were able to recover all deposited amounts from SVB, and continue to have access to all investments held in the SVB Custodial Accounts, there can be no assurance that our current or future banks will not face similar risks as SVB or that we will be able to recover in full our deposits in the event of similar closures. Our investment policy limits investments to money market funds, certain types of debt securities issued by the U.S. Government and its agencies, corporate debt, commercial paper and asset-backed securities, and places restrictions on the credit ratings, maturities and concentration by type and issuer. We have not experienced any significant losses on our deposits of cash, cash equivalents or investments. We are subject to supplier concentration risk from our suppliers. Although we are working to establish secondary sources of supply, we currently source several of our critical raw materials from single-source suppliers. We also use one contract manufacturing organization (“CMO”), Lonza Ltd. (“Lonza”), to handle most of our manufacturing activities for our VAX-24 and VAX-31 programs. If we were to experience disruptions in raw materials supplied by our suppliers, or in manufacturing activities at Lonza, we may experience significant delays in our product development timelines and may incur substantial costs to secure alternative sources of raw materials or manufacturing. Our future results of operations involve a number of other risks and uncertainties. Factors that could affect our future operating results and cause actual results to vary materially from expectations include, but are not limited to: our early stages of clinical vaccine development; our ability to advance vaccine candidates into, and successfully complete, clinical trials on the timelines we project; our ability to adequately demonstrate sufficient safety and immunogenicity or efficacy of our vaccine candidates; our ability to enroll subjects in our ongoing and future clinical trials; our ability to successfully manufacture and supply our vaccine candidates for clinical trials; our ability to obtain additional capital to finance our operations; our ability to obtain, maintain and protect our intellectual property rights; developments relating to our competitors and our industry, including competing vaccine candidates; general and market conditions; and other risks and uncertainties, including those more fully described in the “Risk Factors” section of this Quarterly Report on Form 10-Q.

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2023
Accounting Policies [Abstract]
Schedule of Cash, Cash Equivalents And Restricted Cash	Cash, cash equivalents and restricted cash as reported within the condensed balance sheets that total to the same amounts shown in the condensed statement of cash flows are as follows: March 31, December 31, 2023 2022 (in thousands) Cash and cash equivalents $ 380,451 $ 834,657 Restricted cash 871 871 Cash, cash equivalents and restricted cash $ 381,322 $ 835,528

Fair Value Measurements and F_2

Fair Value Measurements and Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Schedule of Financial Instruments Measured at Fair Value on Recurring Basis	he following tables set forth our financial instruments measured at fair value on a recurring basis by level within the fair value hierarchy at March 31, 2023 and December 31, 2022: March 31, 2023 Fair Value Amortized Gross Gross Fair Assets (in thousands) Cash and cash equivalents: Cash Level 1 $ 38,655 $ — $ — $ 38,655 Money market funds Level 1 82,124 — — 82,124 U.S. Treasury securities Level 1 4,979 — — 4,979 Commercial paper Level 2 254,731 — ( 38 ) 254,693 Total cash and cash equivalents 380,489 — ( 38 ) 380,451 Investments: U.S. Treasury securities Level 1 223,984 218 ( 26 ) 224,176 Commercial paper Level 2 125,074 — ( 10 ) 125,064 Corporate debt Level 2 120,604 11 ( 284 ) 120,331 Asset-backed securities Level 2 21,383 22 - 21,405 U.S. government agency securities Level 2 78,272 193 ( 39 ) 78,426 Total investments 569,317 444 ( 359 ) 569,402 Total assets measured at fair value $ 949,806 $ 444 $ ( 397 ) $ 949,853 December 31, 2022 Fair Value Amortized Gross Gross Fair Assets (in thousands) Cash and cash equivalents: Cash Level 1 $ 56,198 $ — $ — $ 56,198 Money market funds Level 1 680,934 — — 680,934 Commercial paper Level 2 92,581 — ( 34 ) 92,547 U.S. government agency securities Level 2 4,978 — — 4,978 Total cash and cash equivalents 834,691 — ( 34 ) 834,657 Investments: U.S. Treasury securities Level 1 37,651 — ( 70 ) 37,581 Commercial paper Level 2 28,161 — ( 17 ) 28,144 Corporate debt Level 2 25,402 — ( 131 ) 25,271 Asset-backed securities Level 2 6,954 20 — 6,974 U.S. government agency securities Level 2 25,427 19 ( 148 ) 25,298 Total investments 123,595 39 ( 366 ) 123,268 Total assets measured at fair value $ 958,286 $ 39 $ ( 400 ) $ 957,925
Schedule of Contractual Maturities of Investments	The following table presents the contractual maturities of our investments as of March 31, 2023 (in thousands): March 31, 2023 Fair Value Due in less than one year $ 441,587 Due in one to five years 127,815 Total $ 569,402

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	3 Months Ended
	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net as of March 31, 2023 and December 31, 2022 consisted of the following: March 31, December 31, 2023 2022 (in thousands) Furniture and equipment $ 1,608 $ 1,608 Computers and computer software 416 416 Lab equipment 18,656 13,100 Leasehold improvements 1,353 1,353 Total property and equipment 22,033 16,477 Less: accumulated depreciation and amortization ( 6,828 ) ( 6,117 ) Property and equipment, net $ 15,205 $ 10,360
Schedule of Accrued Expenses	Accrued expenses as of March 31, 2023 and December 31, 2022 consisted of the following: March 31, December 31, 2023 2022 (in thousands) Clinical studies $ 1,713 $ 1,518 Other research and development (1) 13,939 12,446 Other accrued expenses 2,699 1,411 Total $ 18,351 $ 15,375 ______________ (1) The balances as of March 31, 2023 and December 31, 2022 include $ 5.0 million of accrued manufacturing rights. See Note 6, “ Commitments and Contingencies, Sutro Option Agreement, ” for further details.

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2023
Leases [Abstract]
Schedule of Information Related to Lease	Information related to our lease are as follows (dollar amounts in thousands): Three Months Ended March 31, March 31, 2023 2022 Cash paid for operating lease liabilities $ 1,671 $ 621 Weighted-average remaining lease term (in years) 2.54 3.54 Weighted-average discount rate 7.6 % 7.6 %
Schedule of Maturities of Lease Liabilities	Maturities of lease liabilities as of March 31, 2023 were as follows: Years ending December 31, (in thousands) Remainder of 2023 $ 4,456 2024 6,850 2025 7,022 Thereafter — Total future undiscounted lease payments 18,328 Less: Imputed interest ( 1,743 ) Total lease liabilities $ 16,585

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Schedule of Non-cancelable Purchase Commitments Related to Raw Materials	As of March 31, 2023, we had the following amounts due of non-cancelable purchase commitments related to manufacturing services and raw materials purchased due to our key manufacturing partners. These amounts represent our minimum contractual obligations, including termination fees. If we terminate certain firm orders with key manufacturing partners, we will be required to pay for the manufacturing services scheduled or raw materials purchased under our arrangements. The actual amounts we pay in the future to our vendors under such agreements may differ from the purchase order amounts. Years ending December 31, (in thousands) Remainder of 2023 $ 97,648 2024 47,478 Total non-cancelable purchase commitments due to our key manufacturing partners $ 145,126

Common Stock (Tables)

Common Stock (Tables)	3 Months Ended
	Mar. 31, 2023
Equity [Abstract]
Schedule of Common Stock Shares Reserved for Future Issuance	Common stock reserved for future issuance under the 2020 Equity Incentive Plan (the “2020 Plan”) and the 2014 Equity Incentive Plan (the “2014 Plan”) was as follows, and excludes 36,710 shares issued outside of the 2014 Plan and 2020 Plan: March 31, December 31, 2023 2022 Options issued and outstanding 9,147,034 7,715,494 Restricted stock units outstanding 773,660 456,766 Shares available for future stock option grants 6,776,052 4,679,598 Total 16,696,746 12,851,858

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	3 Months Ended
	Mar. 31, 2023
Nonvested Restricted Stock Shares Activity	RSU activity for the three months ended March 31, 2023 was as follows: Shares Weighted- Unvested at December 31, 2022 456,766 $ 26.70 Granted 374,458 41.59 Vested and released ( 45,206 ) 24.58 Cancelled ( 12,358 ) 33.67 Unvested at March 31, 2023 773,660 $ 33.92
Summary of Activity under Employee Stock Purchase Plan	Activity under our 2020 ESPP was as follows: Shares Balance - December 31, 2021 1,070,704 Additional shares authorized 530,319 Shares purchased ( 61,709 ) Balance - December 31, 2022 1,539,314 Additional shares authorized 794,706 Shares purchased — Balance - March 31, 2023 2,334,020
Summary of Estimated Fair Value of Employee Stock Options	We estimated the fair value of employee stock options using the Black-Scholes option-pricing model for the three months ended March 31, 2023 and 2022 using the following weighted-average assumptions: Three Months Ended March 31, 2023 2022 Fair Value Assumptions Expected volatility 73.6 % - 74.0 % 78.1 % - 78.9 % Expected dividend yield 0 % 0 % Expected term (in years) 5.3 - 5.4 5.4 Risk-free interest rate 3.7 % - 4.3 % 1.6 % - 2.4 %
2020 Plan and 2014 Plan
Summary of Activity Under Stock Option Plans	Stock options and RSUs activity under our 2020 Plan and 2014 Plan, which excludes options to purchase 36,710 shares granted outside of the 2020 Plan and 2014 Plan, was as follows: Options Outstanding Stock Options and Restricted Stock Units Activity Options and Number Weighted- Weighted- Aggregate Balances — December 31, 2022 4,679,598 7,715,494 $ 18.70 Additional shares authorized 3,973,533 Options granted ( 1,574,642 ) 1,574,642 $ 41.84 Options exercised 1,080 (1) ( 102,044 ) $ 5.40 Options forfeited 41,058 ( 41,058 ) $ 31.95 Restricted stock units granted ( 374,458 ) Restricted stock units withheld 17,525 Restricted stock units forfeited 12,358 Balances — March 31, 2023 6,776,052 9,147,034 $ 22.77 8.32 $ 146,986 Vested and expected to vest — March 31, 2023 9,147,034 $ 22.77 8.32 $ 146,986 Exercisable at March 31, 2023 3,242,028 $ 10.88 6.85 $ 86,670 (1) Net exercise – shares returned to the Plan.
2020 Employee Stock Purchase Plan
Summary of Estimated Fair Value of Shares Under Employee Stock Purchase Plan	We estimated the fair value of shares under the 2020 ESPP using the Black-Scholes option-pricing model for the three months ended March 31, 2023 and 2022 using the following weighted-average assumptions: Three Months Ended March 31, 2023 2022 Fair Value Assumptions Expected volatility 86.4 % - 99.7 % 86.7 % - 97.5 % Expected dividend yield 0 % 0 % Expected term (in years) 0.5 - 2.0 0.5 - 2.0 Risk-free interest rate 4.5 % - 4.7 % 0.1 % - 0.5 %
2014 Plan, 2020 Plan and 2020 ESPP
Summary of Stock-based Compensation Expense	We recorded total stock-based compensation expense for the three months ended March 31, 2023 and 2022 related to the 2014 Plan, the 2020 Plan and the 2020 ESPP in the condensed statements of operations and allocated the amounts as follows: Three Months Ended March 31, 2023 2022 (in thousands) Research and development $ 4,527 $ 1,775 General and administrative 5,121 2,324 Total $ 9,648 $ 4,099

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2023
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Net Loss Per Share	The following table sets forth the computation of basic and diluted net loss per share and excludes shares which are legally outstanding, but subject to repurchase by us: Three Months Ended 2023 2022 Net loss (in thousands) $ ( 60,462 ) $ ( 38,986 ) Weighted-average shares outstanding used in computing net (1) 86,206,817 57,547,808 Net loss per share, basic and diluted $ ( 0.70 ) $ ( 0.68 ) (1) Includes shares of common stock into which pre-funded warrants may be exercised as of March 31, 2023 and does not include any pre-funded warrants issued subsequent to that date. See Note 8 - Pre-Funded Warrants.
Schedule of Potentially Dilutive Securities Excluded From Computation of Diluted Net Loss Per Share	otentially dilutive securities outstanding as of the periods presented below were excluded from the computation of diluted net loss per share for the three months ended March 31, 2023 because including them would have been antidilutive: As of March 31, 2023 2022 Stock options 9,183,744 6,859,801 Restricted stock units 773,660 373,441 Employee stock purchase plan shares 117,203 — Total 10,074,607 7,233,242

Basis of Presentation and Sum_4

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2023 Lease
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Number of finance lease	0

Basis of Presentation and Sum_5

Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Cash, Cash Equivalents And Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Cash and cash equivalents	$ 380,451	$ 834,657
Restricted Cash	871	871
Cash, cash equivalents and restricted cash	$ 381,322	$ 835,528	$ 202,612	$ 69,856

Fair Value Measurements and F_3

Fair Value Measurements and Fair Value of Financial Instruments - Additional Information (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023 USD ($) Security	Dec. 31, 2022 USD ($) Security
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assets transferred into level 3 | $	$ 0	$ 0
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Number of securities | Security	0	0

Fair Value Measurements and F_4

Fair Value Measurements and Fair Value of Financial Instruments - Schedule of Financial Instruments Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets:
Investments, Fair Value	$ 569,402
Fair Value, Recurring
Assets:
Cash and cash equivalents, Amortized Cost	380,489	$ 834,691
Cash and cash equivalents, Gross Unrealized Losses	(38)	(34)
Cash and cash equivalents, Fair Value	380,451	834,657
Investments, Amortized Cost	569,317	123,595
Investments, Gross Unrealized Gains	444	39
Investments, Gross Unrealized Losses	(359)	(366)
Investments, Fair Value	569,402	123,268
Total assets measured at fair value, Amortized Cost	949,806	958,286
Total assets measured at fair value, Gross Unrealized Gains	444	39
Total assets measured at fair value, Gross Unrealized Losses	(397)	(400)
Total assets measured at fair value, Fair Value	949,853	957,925
Fair Value, Recurring | Cash | Level 1
Assets:
Cash and cash equivalents, Amortized Cost	38,655	56,198
Cash and cash equivalents, Fair Value	38,655	56,198
Fair Value, Recurring | Money Market Funds | Level 1
Assets:
Cash and cash equivalents, Amortized Cost	82,124	680,934
Cash and cash equivalents, Fair Value	82,124	680,934
Fair Value, Recurring | Commercial Paper | Level 2
Assets:
Cash and cash equivalents, Amortized Cost	254,731	92,581
Cash and cash equivalents, Gross Unrealized Losses	(38)	(34)
Cash and cash equivalents, Fair Value	254,693	92,547
Fair Value, Recurring | U.S. Treasury Securities | Level 1
Assets:
Cash and cash equivalents, Fair Value	4,979
Investments, Amortized Cost	223,984	37,651
Investments, Gross Unrealized Gains	218
Investments, Gross Unrealized Losses	(26)	(70)
Investments, Fair Value	224,176	37,581
Fair Value, Recurring | Commercial Paper | Level 2
Assets:
Investments, Amortized Cost	125,074	28,161
Investments, Gross Unrealized Losses	(10)	(17)
Investments, Fair Value	125,064	28,144
Fair Value, Recurring | Corporate Debt | Level 2
Assets:
Investments, Amortized Cost	120,604	25,402
Investments, Gross Unrealized Gains	11
Investments, Gross Unrealized Losses	(284)	(131)
Investments, Fair Value	120,331	25,271
Fair Value, Recurring | Asset-backed Securities | Level 2
Assets:
Investments, Amortized Cost	21,383	6,954
Investments, Gross Unrealized Gains	22	20
Investments, Fair Value	21,405	6,974
Fair Value, Recurring | U.S. Government Agency Securities | Level 1
Assets:
Cash and cash equivalents, Amortized Cost	4,979
Fair Value, Recurring | U.S. Government Agency Securities | Level 2
Assets:
Cash and cash equivalents, Amortized Cost		4,978
Cash and cash equivalents, Fair Value		4,978
Investments, Amortized Cost	78,272	25,427
Investments, Gross Unrealized Gains	193	19
Investments, Gross Unrealized Losses	(39)	(148)
Investments, Fair Value	$ 78,426	$ 25,298

Fair Value Measurements and F_5

Fair Value Measurements and Fair Value of Financial Instruments - Schedule of Contractual Maturities of Investments (Details) $ in Thousands	Mar. 31, 2023 USD ($)
Fair Value Disclosures [Abstract]
Due in less than one year	$ 441,587
Due in one to five years	127,815
Total	$ 569,402

Balance Sheet Details - Schedul

Balance Sheet Details - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Property Plant And Equipment [Line Items]
Total property and equipment	$ 22,033	$ 16,477
Less: accumulated depreciation and amortization	(6,828)	(6,117)
Property and equipment, net	15,205	10,360
Furniture and Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	1,608	1,608
Computers and Computer Software
Property Plant And Equipment [Line Items]
Total property and equipment	416	416
Lab Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	18,656	13,100
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 1,353	$ 1,353

Balance Sheet Details - Additio

Balance Sheet Details - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 0.7	$ 0.6
Accrued Manufacturing Rights Expenses	$ 5		$ 5

Balance Sheet Details - Sched_2

Balance Sheet Details - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands		Mar. 31, 2023	Dec. 31, 2022
Accrued Liabilities, Current [Abstract]
Clinical studies		$ 1,713	$ 1,518
Other research and development	[1]	13,939	12,446
Other accrued expenses		2,699	1,411
Total		$ 18,351	$ 15,375
[1] The balances as of March 31, 2023 and December 31, 2022 include $ 5.0 million of accrued manufacturing rights. See Note 6, “ Commitments and Contingencies, Sutro Option Agreement, ” for further details.

Leases - Additional Information

Leases - Additional Information (Details) $ in Thousands	1 Months Ended					3 Months Ended
	Feb. 28, 2022	Jan. 31, 2021 RenewalOption	Nov. 30, 2020	Jul. 31, 2019	Jul. 31, 2016 RenewalOption	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Lessee Lease Description [Line Items]
Operating lease right-of-use assets						$ 19,658		$ 21,288
Operating lease liabilities						16,585
Operating leases, rent expense recognized						$ 1,900	$ 2,200
Headquarters Facility
Lessee Lease Description [Line Items]
Operating lease, agreement term					5 years
Operating lease, commencement date					Sep. 01, 2016
Lease Termination Date	Feb. 12, 2022
Lease expiration date					Aug. 31, 2021
Operating lease, renewal option | RenewalOption					2
Operating lease, renewal term					30 months
Operating lease, option to renewal, description						30-month renewal options
Operating lease, existence of option to renewal					true
Operating lease, description						In July 2016, we entered into a five-year lease agreement for our previous headquarters facility located in Foster City, California. The original term of the lease was from September 1, 2016 to August 31, 2021, with two 30-month renewal options.
Operating lease, extended term			6 months
Operating lease, extended maturity date			Mar. 01, 2022
Additional Facility
Lessee Lease Description [Line Items]
Operating lease, commencement date				Jul. 01, 2019
Lease expiration date				Oct. 31, 2021
Operating lease, option to renewal, description						no renewal options
Operating lease, existence of option to renewal				false
Operating lease, description						In July 2019, we leased another facility in Foster City, California as a result of growth in personnel and lab space requirements. The original term of this lease was from July 1, 2019 to October 31, 2021, with no renewal options.
Operating lease, extended term			6 months
Operating lease, extended maturity date			Apr. 30, 2022
New Corporate Headquarters Facility
Lessee Lease Description [Line Items]
Operating lease, commencement date		Dec. 03, 2021
Lease expiration date		Dec. 31, 2025
Operating lease, renewal term		60 months
Operating lease, extended term		60 days
Number of renewal options | RenewalOption		2
Palo Alto
Lessee Lease Description [Line Items]
Operating lease, extended maturity date		Mar. 03, 2022
San Carlos
Lessee Lease Description [Line Items]
Operating lease right-of-use assets						$ 28,400
Operating lease liabilities						$ 12,900

Leases - Schedule of Informatio

Leases - Schedule of Information Related to ROU Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Leases [Abstract]
Cash paid for operating lease liabilities	$ 1,671	$ 621
Operating lease right-of-use assets	19,658		$ 21,288
Current operating lease liabilities	5,947		5,910
Non-current operating lease liabilities	10,638		$ 12,031
Total lease liabilities	$ 16,585
Weighted-average remaining lease term (in years)	2 years 6 months 14 days	3 years 6 months 14 days
Weighted-average discount rate	7.60%	7.60%

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Lease Liabilities (Details) $ in Thousands	Mar. 31, 2023 USD ($)
Leases [Abstract]
Remainder of 2023	$ 4,456
2024	6,850
2025	7,022
Total future undiscounted lease payments	18,328
Less: Imputed interest	(1,743)
Total lease liabilities	$ 16,585

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		3 Months Ended	12 Months Ended
	Jun. 30, 2021	Apr. 30, 2021	Mar. 31, 2023	Dec. 31, 2022
Loss Contingencies [Line Items]
Payments in equity, amount	$ 10
Lonza DMSA
Loss Contingencies [Line Items]
Percentage of defer payments agreed for completion		50%
Amount recorded with respect to the potential future payments above the initial cash cap		$ 10
Number of common stock issued	399,680
Public offering price per share	$ 25.02
Sutro Biopharma Inc
Loss Contingencies [Line Items]
Number of common stock issued				167,780
Upfront Consideration				$ 22.5
Upfront Consideration in Cash				10
Upfront Consideration in Cash After Agreement Date				5
Option Exercise Price in Cash				75
Additional Milestone Payments in Cash				60
Accrued Commitment			$ 5	5
Fair Value on Date of Settlement				8
Sutro Biopharma Inc | Common Stock [Member]
Loss Contingencies [Line Items]
Upfront Consideration				$ 7.5

Commitments and Contingencies_2

Commitments and Contingencies - Schedule Of non-cancelable purchase commitments related to raw materials - (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Remainder of 2023	$ 97,648
2024	47,478
Total non-cancelable purchase commitments due to our key manufacturing partners	$ 145,126

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - USD ($)			1 Months Ended		3 Months Ended		12 Months Ended
	Oct. 28, 2022	Jan. 13, 2022	Feb. 27, 2023	Feb. 28, 2022	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022	Jul. 31, 2021
Class of Stock [Line Items]
Common stock, shares authorized					500,000,000		500,000,000
Common stock, par value per share					$ 0.001		$ 0.001
Common stock, shares issued					80,640,851		79,470,670
Common stock, shares outstanding					80,640,851		79,470,670
Common stock, dividends, per share, declared					$ 0		$ 0
Common stock, voting rights					Each share of common stock is entitled to one vote.
Proceeds from issuance of stock, net of commission and offering expenses					$ 41,787,000	$ 3,115,000
Equity incentive plan, shares issued					36,710
Over Allotment Option
Class of Stock [Line Items]
Shares issued	17,812,500	2,500,000
Common stock price per share	$ 32	$ 20
Pre-funded warrants to purchase shares	3,750,000	2,500,000
Prefunded Warrants Price Per Share	$ 31.999	$ 19.999
Underwriters' option to purchase additional shares	2,812,500			750,000
Net proceeds from follow on offering	$ 651,600,000			$ 107,600,000
ATM Sales Agreement
Class of Stock [Line Items]
Aggregate offering price			$ 150,000,000
ATM Sales Agreement | Jefferies LLC
Class of Stock [Line Items]
Aggregate offering price			$ 137,800,000
Maximum commission percentage of gross proceeds from common stock sold								3%
Common stock shares sold			4,995,709		534,400
Average price			$ 27.57		$ 37.42
Aggregate gross proceeds from issuance of common stock					$ 20,000,000
Proceeds from issuance of stock, net of commission and offering expenses					$ 19,600,000
ATM Sales Agreement | Maximum | Jefferies LLC
Class of Stock [Line Items]
Aggregate offering price			$ 400,000,000					$ 150,000,000

Common Stock - Schedule of Comm

Common Stock - Schedule of Common Stock Shares Reserved for Future Issuance (Details) - 2020 Plan and 2014 Plan - shares	Mar. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Common stock reserved for future issuances	16,696,746	12,851,858
Options Issued and Outstanding
Class of Stock [Line Items]
Common stock reserved for future issuances	9,147,034	7,715,494
Restricted stock units outstanding
Class of Stock [Line Items]
Common stock reserved for future issuances	773,660	456,766
Shares Available for Future Stock Option Grants
Class of Stock [Line Items]
Common stock reserved for future issuances	6,776,052	4,679,598

Pre-Funded Warrants - Additiona

Pre-Funded Warrants - Additional Information (Details) - $ / shares	1 Months Ended
	Oct. 31, 2022	Jan. 31, 2022	Mar. 31, 2023
Class of Stock [Line Items]
Warrant exercised	0.001	0.001	0
Increase or Decrease of Pre-funded Warrant Percentage Not Exceed	19.99%	19.99%
Minimum
Class of Stock [Line Items]
Pre-funded warrants of common stock shares outstanding Immediately after effect to the exercise	4.99%	4.99%
Combined voting power of securities outstanding immediately after effect to the exercise	4.99%	4.99%
Maximum
Class of Stock [Line Items]
Pre-funded warrants of common stock shares outstanding Immediately after effect to the exercise	9.99%	9.99%
Combined voting power of securities outstanding immediately after effect to the exercise	9.99%	9.99%
Over Allotment Option
Class of Stock [Line Items]
Shares issued	17,812,500	3,250,000
Common stock price per share	$ 32	$ 20
Pre-funded warrants to purchase shares	3,750,000	2,500,000
Prefunded Warrants Price Per Share	$ 31.999	$ 19.999
Pre-funded warrant recorded as a component of stockholders' equity within additional paid-in-capital	$ 0.001	$ 0.001

Equity Incentive Plans - Additi

Equity Incentive Plans - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended
	Jan. 01, 2023	Jun. 11, 2020	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage for stock options granted		25%
Vesting period for stock options granted		4 years
Early exercised stock options			2,779		3,705
Options granted			36,710
Exercise of stock options (in shares)			100,964	91,044
Weighted-average price per share			$ 5.40	$ 3.18
Weighted-average grant date fair value of options granted			$ 27.18	$ 16.34
Intrinsic value of the stock options exercised			$ 3.8	$ 1.8
Restricted stock units outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage for stock options granted		25%
Vesting percentage for stock options granted, Six months thereafter		12.50%
Vesting period for stock options granted		4 years
Other Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage for stock options granted, Six months thereafter		12.50%
Vesting period for stock options granted		3 years 6 months
Weighted-average grant date fair value of options granted			$ 41.59	$ 24.67
Unrecognized stock-based compensation cost			$ 24.4
Unrecognized share-based compensation expense, expected to be recognized			3 years 1 month 6 days
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price expire in years form the date of grant		5 years
Stock options granted term		10 years
Percentage of provisions subject to stockholders		10%
Shares reserved for issuance		10,150,000
Term of plan		10 years
Percentage of outstanding number of shares		5%
Aggregate number of shares available for issuance			6,776,052
Available for issuance of shares increased			3,973,533
2020 Equity Incentive Plan | Restricted stock units outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares outstanding			7,432,127
2014 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares outstanding			2,488,567
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for issuance		650,000
Term of plan		10 years
Percentage of outstanding number of shares		1%
Available for issuance of shares increased	794,706
Employees purchase shares of common stock of lower of fair market value		85%
Offering period		2 years
Purchase period		6 months
Percentage of payroll deductions of eligible compensation		15%
Minimum | 2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incentive stock option granted to employees owning percentage of shares of common stock		10%
Maximum | Other Liabilities
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Remaining liabilities related to early exercised shares			$ 0.1		$ 0.1
Maximum | 2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of fair value per share on the grant date		110%

Equity Incentive Plans - Summar

Equity Incentive Plans - Summary of Activity Under Stock Option Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options, granted	36,710
Weighted-Average Exercise Price Per Share, Options exercised	$ 5.40	$ 3.18
2020 Plan and 2014 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and Restricted Stock Units Available for Grant, Beginning Balance	4,679,598
Options and Restricted Stock Units Available for Grant, Additional shares authorized	3,973,533
Options and Restricted Stock Units Available for Grant, granted	(1,574,642)
Options and Restricted Stock Units Available for Grant, exercised	1,080
Options and Restricted Stock Units Available for Grant, forfeited	41,058
Options and Restricted Stock Units Available for Grant, Ending Balance	6,776,052
Number of Options, Beginning Balance	7,715,494
Number of Options, granted	1,574,642
Number of Options, exercised	(102,044)
Number of Options, forfeited	(41,058)
Number of Options, Ending Balance	9,147,034
Number of Options, Vested and expected to vest	9,147,034
Number of Options, Exercisable	3,242,028
Weighted-Average Exercise Price Per Share, Beginning Balance	$ 18.70
Weighted-Average Exercise Price Per Share, Options granted	41.84
Weighted-Average Exercise Price Per Share, Options exercised	5.40
Weighted-Average Exercise Price Per Share, Options forfeited	31.95
Weighted-Average Exercise Price Per Share, Ending Balance	22.77
Weighted-Average Exercise Price Per Share, Vested and expected to vest	22.77
Weighted-Average Exercise Price Per Share, Exercisable	$ 10.88
Weighted-Average Remaining Contractual Term (Years)	8 years 3 months 25 days
Weighted-Average Remaining Contractual Term (Years), Vested and expected to vest	8 years 3 months 25 days
Weighted-Average Remaining Contractual Term (Years), Exercisable	6 years 10 months 6 days
Aggregate Intrinsic Value	$ 146,986
Aggregate Intrinsic Value, Vested and expected to vest	146,986
Aggregate Intrinsic Value, Exercisable	$ 86,670
2020 Plan and 2014 Plan | Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options and Restricted Stock Units Available for Grant, granted	(374,458)
Options and Restricted Stock Units Available for Grant, forfeited	12,358
Restricted stock units withheld	17,525

Equity Incentive Plans - Nonves

Equity Incentive Plans - Nonvested Restricted Stock Shares Activity (Details)	3 Months Ended
	Mar. 31, 2023 USD ($) shares
Share-Based Payment Arrangement [Abstract]
Beginning balance | shares	456,766
Granted | shares	374,458
Vested and released | shares	(45,206)
Cancelled | shares	(12,358)
Ending balance | shares	773,660
Weighted average grant date fair value, Beginning balance | $	$ 26,700
Weighted average grant date fair value, granted | $	41,590
Weighted average grant date fair value, cancelled | $	33,670
Weighted average grant date fair value, vested and released | $	24,580
Weighted average grant date fair value, Ending balance | $	$ 33,920

Equity Incentive Plans - Summ_2

Equity Incentive Plans - Summary of Activity under Employee Stock Purchase Plan (Details) - shares	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Beginning balance	456,766
Ending balance	773,660	456,766
2020 Employee Stock Purchase Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Beginning balance	1,539,314	1,070,704
Additional shares authorized	794,706	530,319
Shares purchased	0	(61,709)
Ending balance	2,334,020	1,539,314

Equity Incentive Plans - Summ_3

Equity Incentive Plans - Summary of Estimated Fair Value of Employee Stock Options (Details)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Fair Value Assumptions
Expected volatility, Minimum	73.60%	78.10%
Expected volatility, Maximum	74%	78.90%
Expected dividend yield	0%	0%
Expected term (in years)		5 years 4 months 24 days
Risk-free interest rate, Minimum	3.70%	1.60%
Risk-free interest rate, Maximum	4.30%	2.40%
Minimum
Fair Value Assumptions
Expected term (in years)	5 years 3 months 18 days
Maximum
Fair Value Assumptions
Expected term (in years)	5 years 4 months 24 days

Equity Incentive Plans - Summ_4

Equity Incentive Plans - Summary of Estimated Fair Value of Shares Under Employee Stock Purchase Plan (Details)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Fair Value Assumptions
Expected volatility, Minimum	73.60%	78.10%
Expected volatility, Maximum	74%	78.90%
Expected dividend yield	0%	0%
Expected term (in years)		5 years 4 months 24 days
Risk-free interest rate, Minimum	3.70%	1.60%
Risk-free interest rate, Maximum	4.30%	2.40%
Minimum
Fair Value Assumptions
Expected term (in years)	5 years 3 months 18 days
Maximum
Fair Value Assumptions
Expected term (in years)	5 years 4 months 24 days
2020 Employee Stock Purchase Plan
Fair Value Assumptions
Expected volatility, Minimum	86.40%	86.70%
Expected volatility, Maximum	99.70%	97.50%
Expected dividend yield	0%	0%
Risk-free interest rate, Minimum	4.50%	0.10%
Risk-free interest rate, Maximum	4.70%	0.50%
2020 Employee Stock Purchase Plan | Minimum
Fair Value Assumptions
Expected term (in years)	6 months	6 months
2020 Employee Stock Purchase Plan | Maximum
Fair Value Assumptions
Expected term (in years)	2 years	2 years

Equity Incentive Plans - Summ_5

Equity Incentive Plans - Summary of Stock-based Compensation Expense (Details) - 2014 Plan, 2020 Plan and 2020 ESPP - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 9,648	$ 4,099
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	4,527	1,775
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 5,121	$ 2,324

Retirement Plan - Additional In

Retirement Plan - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Retirement Benefits [Abstract]
Company contributions	$ 0.4	$ 0.2

Funding Arrangement - Additiona

Funding Arrangement - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended
	Apr. 30, 2021	Jul. 31, 2019	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Funding Arrangement [Line Items]
Grant income			$ 654	$ 160
Cost Reimbursement Sub-Award Agreement
Funding Arrangement [Line Items]
Funding period of award to develop universal vaccine to prevent infections caused by Group A Strep bacteria		4 years
Potential funding amount of award to develop vaccine to prevent shingella infections	$ 500
Grant income			700	$ 200
Cost Reimbursement Sub-Award Agreement | Maximum
Funding Arrangement [Line Items]
Initial funding committed by award		$ 1,600
Total funding committed by award, available upon achievement of development milestones		15,100
Potential funding period of award to develop vaccine to prevent shingella infections	5 years
CARB-X Agreement
Funding Arrangement [Line Items]
Grant receivable on unreimbursed, eligible costs incurred			$ 1,300		$ 1,000
CARB-X Agreement | Maximum
Funding Arrangement [Line Items]
Initial funding committed by award		14,600
CARB-X Agreement | Minimum
Funding Arrangement [Line Items]
Potential funding committed by award		$ 11,700

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Earnings Per Share [Abstract]
Net loss (in thousands)	$ (60,462)	$ (38,986)
Weighted Average Number of Shares Outstanding, Basic	86,206,817	57,547,808
Weighted Average Number of Shares Outstanding, Diluted	86,206,817	57,547,808
Earnings Per Share, Basic	$ (0.70)	$ (0.68)
Earnings Per Share, Diluted	$ (0.70)	$ (0.68)

Net Loss Per Share - Schedule_2

Net Loss Per Share - Schedule of Potentially Dilutive Securities Excluded From Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - shares	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	10,074,607	7,233,242
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	773,660	373,441
Employee Stock Purchase Plan [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	117,203	0
Options Issued and Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per share	9,183,744	6,859,801

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details)	3 Months Ended
	Mar. 31, 2023 USD ($)
Income Tax Disclosure [Abstract]
Tax provision	$ 0

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - Over Allotment Option - USD ($) $ / shares in Units, $ in Millions				1 Months Ended
	Apr. 21, 2023	Oct. 28, 2022	Jan. 13, 2022	Feb. 28, 2022
Subsequent Event [Line Items]
Shares issued		17,812,500	2,500,000
Underwriters' option to purchase additional shares		2,812,500		750,000
Common stock price per share		$ 32	$ 20
Pre-funded warrants to purchase shares		3,750,000	2,500,000
Prefunded Warrants Price Per Share		$ 31.999	$ 19.999
Net proceeds from follow on offering		$ 651.6		$ 107.6
Subsequent Event
Subsequent Event [Line Items]
Shares issued	13,030,000
Underwriters' option to purchase additional shares	1,830,000
Common stock price per share	$ 41
Pre-funded warrants to purchase shares	1,000,000
Prefunded Warrants Price Per Share	$ 40.999
Net proceeds from follow on offering	$ 545.1