Icosavax (ICVX) 10-Q 16 May 22 2022 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2022	May 09, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2022
Document Fiscal Year Focus	2022
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q1
Entity Registrant Name	ICOSAVAX, INC.
Entity Central Index Key	0001786255
Entity File Number	001-40655
Entity Tax Identification Number	82-3640549
Entity Current Reporting Status	No
Entity Shell Company	false
Entity Filer Category	Non-accelerated Filer
Entity Interactive Data Current	Yes
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Address Address Line1	1616 Eastlake Avenue E.
Entity Address, Address Line Two	Suite 208
Entity Address City Or Town	Seattle
Entity Address, State and Province	WA
Entity Incorporation State Country Code	DE
Entity Address Postal Zip Code	98102
Local Phone Number	737-0085
City Area Code	206
Security12b Title	Common Stock, $0.0001 par value per share
Trading Symbol	ICVX
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		39,726,829

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash	$ 261,357	$ 279,082
Restricted cash	1,061	1,642
Prepaid expenses and other current assets	7,681	5,829
Total current assets	270,099	286,553
Right-of-use assets - operating leases	3,309
Property and equipment, net	3,237	1,076
Total assets	276,645	287,629
Current liabilities:
Accounts payable	6,019	3,899
Accrued and other current liabilities	7,448	4,757
Current portion of operating lease liabilities	530
Deferred revenue		582
Total current liabilities	13,997	9,238
Operating lease liabilities, net of current portion	2,964
Other noncurrent liabilities	144	171
Total liabilities	17,105	9,409
Commitments and contingencies (Note 2)
Stockholders' equity (deficit):
Common stock, $0.0001 par value; 500,000,000 shares authorized at March 31, 2022 and December 31, 2021; 39,724,867 and 39,429,103 shares issued as of March 31, 2022 and December 31, 2021, respectively; 39,524,526 and 39,175,279 shares outstanding as of March 31, 2022 and December 31, 2021, respectively	5	5
Additional paid-in capital	377,137	372,284
Accumulated deficit	(117,602)	(94,069)
Total stockholders' equity (deficit)	259,540	278,220
Total liabilities, convertible preferred stock and stockholders' equity (deficit)	$ 276,645	$ 287,629

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Aug. 02, 2021	Mar. 31, 2021	Dec. 31, 2020
Convertible preferred stock, aggregate liquidation preference				$ 150,837
Preferred stock, shares authorized			50,000,000
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	500,000,000	500,000,000	500,000,000
Common stock, shares issued	39,724,867	39,429,103
Common Stock Shares Outstanding	39,524,526	39,175,279
Convertible Preferred Stock [Member]
Convertible preferred stock, shares outstanding				89,908,215	32,198,879

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Grant revenue	$ 582	$ 2,001
Operating expenses:
Research and development	17,913	5,553
General and administrative	6,322	1,091
Total operating expenses	24,235	6,644
Loss from operations	(23,653)	(4,643)
Other income (expense):
Change in fair value of embedded derivative liability	0	(205)
Loss on extinguishment of convertible promissory note	0	(754)
Interest and other income (expense)	120	(249)
Total other income (expense)	120	(1,208)
Net loss and comprehensive loss	$ (23,533)	$ (5,851)
Net loss per share, basic and diluted	$ (0.60)	$ (2.11)
Weighted-average common shares outstanding, basic and diluted	39,401,805	2,769,962

Condensed Statements of Convert

Condensed Statements of Convertible Preferred Stock and Stockholder's Deficit (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Accumulated Deficit [Member]	Convertible Preferred Stock [Member]
Beginning Balance at Dec. 31, 2020	$ (26,703)	$ 2	$ 393	$ (27,098)
Beginning Balance (in shares) at Dec. 31, 2020		2,639,026
Convertible preferred stock, Beginning Balance at Dec. 31, 2020					$ 30,062
Convertible preferred stock, Beginning Balance (in shares) at Dec. 31, 2020					32,198,879
Issuance of Series A-1 convertible preferred stock					$ 21,005
Issuance of Series A-1 convertible preferred stock, (in shares)					21,944,874
Issuance of Series B-1 convertible preferred stock					$ 92,654
Issuance of Series B-1 convertible preferred stock, (in shares)					32,958,612
Issuance of Series B-2 convertible preferred stock from convertible note					$ 7,917
Issuance of Series B-2 convertible preferred stock from convertible note (in shares)					2,805,850
Shares released from restriction upon vesting of early-exercised stock options	63		63
Shares released from restriction upon vesting of early-exercised stock options (in shares)		100,238
Exercise of common stock options	29		29
Exercise of common stock options, (in shares)		35,143
Vesting of shares of restricted common stock (in Shares)		117,369
Stock-based compensation	276		276
Net loss and comprehensive loss	(5,851)			(5,851)
Ending Balance at Mar. 31, 2021	(32,186)	$ 2	761	(32,949)
Ending Balance (in shares) at Mar. 31, 2021		2,891,776
Convertible preferred stock, Ending Balance at Mar. 31, 2021					$ 151,638
Convertible preferred stock, Ending Balance (in shares) at Mar. 31, 2021					89,908,215
Beginning Balance at Dec. 31, 2021	278,220	$ 5	372,284	(94,069)
Beginning Balance (in shares) at Dec. 31, 2021		39,175,279
Shares released from restriction upon vesting of early-exercised stock options	27		27
Shares released from restriction upon vesting of early-exercised stock options (in shares)		53,483
Exercise of common stock options	$ 276		276
Exercise of common stock options, (in shares)	295,764	295,764
Stock-based compensation	$ 4,550		4,550
Net loss and comprehensive loss	(23,533)			(23,533)
Ending Balance at Mar. 31, 2022	$ 259,540	$ 5	$ 377,137	$ (117,602)
Ending Balance (in shares) at Mar. 31, 2022		39,524,526

Condensed Statements of Conve_2

Condensed Statements of Convertible Preferred Stock and Stockholder's Deficit (Unaudited) (Parenthetical) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)$ / shares
Series A1 Convertible Preferred Stock
Convertible preferred stock issuance cost, per share | $ / shares	$ 0.9615
Convertible preferred stock issuance cost, net | $	$ 0.1
Series B1 Convertible Preferred Stock
Convertible preferred stock issuance cost, per share | $ / shares	$ 2.82172
Convertible preferred stock issuance cost, net | $	$ 0.3

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities:
Net loss	$ (23,533)	$ (5,851)
Adjustments to reconcile net loss to cash used in operating activities:
Stock-based compensation	4,550	276
Depreciation	43	1
Non-cash lease expense	185
Non-cash interest expense		264
Change in fair value of embedded derivative liability	0	205
Loss on extinguishment of convertible promissory note	0	754
Changes in operating assets and liabilities:
Prepaids and other current assets	(1,852)	436
Accounts payable	1,038	(205)
Accrued & other current liabilities	2,691	(761)
Deferred revenue	(582)	699
Net cash used in operating activities	(17,460)	(4,182)
Investing activities:
Purchases of property and equipment	(1,122)	(134)
Net cash used in investing activities	(1,122)	(134)
Financing activities:
Proceeds from issuance of convertible preferred stock, net of issuance costs		113,659
Proceeds from exercise of stock options, including early exercise	276	120
Net cash provided by financing activities	276	113,779
Net (decrease) increase in cash and restricted cash	(18,306)	109,463
Cash and restricted cash at beginning of period	280,724	15,498
Cash and restricted cash at end of period	262,418	124,961
Supplemental disclosure of noncash activities
Purchases of property and equipment included in accounts payable and accrued liabilities	1,224
Right-of-use assets and lease liabilities recognized upon commencement of lease	3,370
Conversion of convertible note (including accrued interest) and derivative liability for Series B-2 convertible preferred stock		7,917
Deferred offering costs included in accounts payable and accrued and other current liabilities		81
Issuance costs and amounts payable for convertible preferred stock included in accounts payable and accrued liabilities		$ 163

Description of Business

Description of Business	3 Months Ended
	Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	1. Description of Business Organization Icosavax, Inc. (the “Company”) was incorporated in the state of Delaware on November 1, 2017, and is located in Seattle, Washington. The Company is focused on the research and development of vaccines against infectious diseases. The Company was founded on computationally designed virus-like particle technology, exclusively licensed for a variety of infectious disease indications from the Institute for Protein Design at the University of Washington. The Company’s business involves inherent risks. These risks include, among others, dependence on key personnel, licensors and third-party service providers, patentability of the Company’s products and processes, the immunogenicity, efficacy and safety of the Company’s vaccine candidates and the potential of the Company’s novel vaccine technology platform. In addition, any of the Company’s vaccine candidates, and the Company’s vaccine technology platform, could become obsolete or diminished in value by discoveries and developments at other organizations. In July 2021, the Company effected a 1-for-4.1557 reverse stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each series of the Company’s convertible preferred stock. Accordingly, all share and per share amounts for all periods presented in the accompanying condensed financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse stock split and adjustment of the convertible preferred stock conversion ratios. On August 2, 2021, the Company completed its initial public offering (“IPO” ) pursuant through which it issued 12,133,333 shares of its common stock at a public offering price of $ 15.00 per share, and on August 2, 2021, the Company sold an additional 1,819,999 shares pursuant to the exercise by the underwriters of their option to purchase additional shares. The Company received net proceeds from its IPO, inclusive of the exercise by the underwriters of their option to purchase additional shares, of $ 190.7 million, after deducting underwriting discounts and commissions and offering expenses. Upon the closing of the IPO, all 89,908,215 shares of the then outstanding convertible preferred stock automatically converted into 21,634,898 shares of common stock. Liquidity The Company had an accumulated deficit of $ 117.6 million, cash of $ 261.4 million, and restricted cash of $ 1.1 million at March 31, 2022. Management believes the Company has sufficient capital to execute its strategic plan and fund operations through at least the next twelve months from the date these condensed financial statements are issued. The Company has devoted substantially all its resources to organizing and staffing the Company, business planning, raising capital, in-licensing intellectual property rights, developing vaccine candidates, scaling up manufacturing of vaccine candidates, and preparing for its ongoing and planned preclinical studies and clinical trials. The Company has a limited operating history, and the sales and income potential of its business is unproven. The Company has incurred net losses and negative cash flows from operating activities since its inception and expects to continue to incur net losses into the foreseeable future as it continues the development of its vaccine candidates. From inception to March 31, 2022, the Company has funded its operations primarily through the sale of its convertible preferred stock and common stock. As the Company continues to pursue its business plan, it expects to finance its operations through equity offerings, debt financings or other capital sources, including potential strategic collaborations, licenses, and other similar arrangements. However, there can be no assurance that any additional financing or strategic transactions will be available to the Company on acceptable terms, if at all. If events or circumstances occur such that the Company does not obtain additional funding, it may need to delay, reduce or eliminate its product development or future commercialization efforts, which could have a material adverse effect on the Company’s business, results of operations or financial condition. The accompanying financial statements do not include any adjustments that might be necessary if the Company were unable to continue as a going concern.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed financial statements as of March 31, 2022 and for the three months ended March 31, 2022 and 2021 have been prepared in conformity with generally accepted accounting principles (“GAAP”) in the United States of America for interim financial information and pursuant to Article 10 of Regulation S-X of the Securities Act of 1933, as amended (the “Securities Act”). Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. These unaudited condensed financial statements include only normal and recurring adjustments that the Company believes are necessary to fairly state the Company’s financial position and the results of its operations and cash flows. The results for the three months ended March 31, 2022 are not necessarily indicative of the results expected for the full fiscal year or any subsequent interim period. The condensed balance sheet at December 31, 2021 has been derived from the audited financial statements at that date but does not include all disclosures required by GAAP for complete financial statements. Because all of the disclosures required by GAAP for complete financial statements are not included herein, these unaudited condensed financial statements and the notes accompanying them should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2021 included in the Annual Report on Form 10-K (the "Annual Report") that the Company filed with the Securities and Exchange Commission (the “SEC”) on March 30, 2022. Use of Estimates The Company’s significant accounting policies are described in Note 2, “Summary of significant accounting policies,” of the Company’s audited financial statements for the year ended December 31, 2021 included in the Annual Report. There have been no material changes to the significant accounting policies previously disclosed in those audited financial statements. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including expenses, clinical trials and research and development costs, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain or treat COVID-19, as well as the economic impact on local, regional, national and international markets. The Company has considered potential impacts arising from the COVID-19 pandemic and is not presently aware of any events or circumstances that would require the Company to update its estimates, judgments or revise the carrying value of its assets or liabilities. Fair Value of Financial Instruments The accounting guidance defines fair value, establishes a consistent framework for measuring fair value, and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as an exit price representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. The carrying amounts of all cash, restricted cash, prepaid expenses and other assets, accounts payable, and accrued and other current liabilities are considered to be representative of their respective fair values due to their short maturities. Derivative Liability, Convertible Notes Discount and Amortization The Company’s convertible note (see Note 7) had conversion and redemption features that met the definition of an embedded derivative and were therefore subject to bifurcation and derivative accounting. The initial recognition of the fair value of the derivative resulted in a discount to the convertible note, with a corresponding derivative liability. The discount to the convertible note was amortized using the effective interest method. The amortization of the discount is included in interest and other income (expense) in the statements of operations and comprehensive loss. The derivative liability related to these features was recorded at estimated fair value and remeasured on a recurring basis. Any changes in fair value were reflected as change in fair value of derivative liability in the statements of operations and comprehensive loss at each reporting date while such instruments were outstanding. The derivative liability was settled in March 2021 upon conversion of the underlying convertible note into Series B convertible preferred stock, resulting in a loss on extinguishment of the convertible promissory note. Leases At the inception of a contractual arrangement, the Company determines whether the contract contains a lease by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration over a period of time. If both criteria are met, the Company records the associated lease liability and corresponding right-of-use ("ROU") asset upon commencement of the lease using the implicit rate or a discount rate based on a credit-adjusted secured borrowing rate commensurate with the term of the lease. The Company additionally evaluates leases at their inception to determine if they are to be accounted for as an operating lease or a finance lease. A lease is accounted for as a finance lease if it meets one of the following five criteria: the lease has a purchase option that is reasonably certain of being exercised, the present value of the future cash flows is substantially all of the fair market value of the underlying asset, the lease term is for a significant portion of the remaining economic life of the underlying asset, the title to the underlying asset transfers at the end of the lease term, or if the underlying asset is of such a specialized nature that it is expected to have no alternative uses to the lessor at the end of the term. Leases that do not meet the finance lease criteria are accounted for as an operating lease. Operating lease assets represent a right to use an underlying asset for the lease term and operating lease liabilities represent an obligation to make lease payments arising from the lease. Operating lease liabilities with a term greater than one year and their corresponding ROU assets are recognized on the balance sheet at the commencement date of the lease based on the present value of lease payments over the expected lease term. Certain adjustments to the ROU asset may be required for items such as initial direct costs paid or incentives received. As the Company’s leases do not typically provide an implicit rate, the Company utilizes the appropriate incremental borrowing rate, determined as the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term and in a similar economic environment. Lease cost is recognized on a straight-line basis over the lease term and variable lease payments are recognized as operating expenses in the period in which the obligation for those payments is incurred. Variable lease payments primarily include common area maintenance, utilities, real estate taxes, insurance, and other operating costs that are passed on from the lessor in proportion to the space leased by the Company. The Company has elected the practical expedient to not separate lease and non-lease components. Liability for Early Exercise of Stock Options Certain individuals were granted the ability to early exercise their stock options. The shares of common stock issued from the early exercise of unvested stock options are restricted and continue to vest in accordance with the original vesting schedule. The Company has the option to repurchase any unvested shares at the original purchase price upon any voluntary or involuntary termination. The shares purchased by the employees and non-employees pursuant to the early exercise of stock options are not deemed, for accounting purposes, to be outstanding until those shares vest. The cash received in exchange for exercised and unvested shares related to stock options granted is recorded as a liability for the early exercise of stock options on the accompanying balance sheets and will be reclassified as common stock and additional paid-in capital as the shares vest. Unvested shares issued under early exercise provisions subject to repurchase by the Company totaled 200,341 and 253,824 shares as of March 31, 2022 and December 31, 2021, respectively. As of March 31, 2022 and December 31, 2021, the Company recorded $ 0.1 million and $ 0.2 million respectively, associated with shares issued with repurchase rights as other noncurrent liabilities in the accompanying condensed balance sheets. Commitments and Contingencies The Company recognizes a liability with regard to loss contingencies when it believes it is probable a liability has been incurred, and the amount can be reasonably estimated. If some amount within a range of loss appears at the time to be a better estimate than any other amount within the range, the Company accrues that amount. When no amount within the range is a better estimate than any other amount the Company accrues the minimum amount in the range. In the event the Company becomes subject to claims or suits arising in the ordinary course of business, the Company would accrue a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. The Company has not recorded any such liabilities at either March 31, 2022 or December 31, 2021. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted- average number of shares of common stock outstanding for the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and common stock equivalents outstanding for the period. Common stock equivalents are only included when their effect is dilutive. The Company’s potentially dilutive securities include outstanding stock options under the Company’s equity incentive plan and have been excluded from the computation of diluted net loss per share as they would be anti-dilutive to the net loss per share. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position. The following tables summarize the computation of the basic and diluted net loss per share (in thousands, except share and per share data): Three Months Ended 2022 2021 Numerator: Net loss $ ( 23,533 ) $ ( 5,851 ) Denominator: Weighted-average common shares outstanding, basic and 39,602,146 3,674,126 Less: Weighted average unvested common stock ( 200,341 ) ( 904,164 ) Weighted average shares used to compute net loss per 39,401,805 2,769,962 Net loss per share, basic and diluted $ ( 0.60 ) $ ( 2.11 ) The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their inclusion would be anti-dilutive. As of March 31, 2022 2021 Series A convertible preferred stock — 54,143,753 Series B convertible preferred stock — 35,764,462 Common stock options and restricted stock units 8,525,522 1,717,446 Unvested common stock 200,341 849,884 Total 8,725,863 92,475,545 Segments The Company has determined that it operates and manages one operating segment, which is the business of researching and developing vaccines against infectious diseases. The Company’s chief operating decision maker, its chief executive officer, reviews financial information on an aggregate basis for the purpose of allocating resources. All assets of the Company are located in the United States. Recent Accounting Pronouncements Recently Adopted Accounting Standards In December 2019, the FASB issued ASU 2019-12, Income Taxes—Simplifying the Accounting for Income Taxes (“ASU 2019-12”). The new guidance simplifies the accounting for income taxes by removing several exceptions in the current standard and adding guidance to reduce complexity in certain areas, such as requiring that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date. The new standard is effective for fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022 for all non-public entities, with early adoption permitted, and is effective for fiscal years beginning after December 15, 2020, including interim periods within those annual periods for public entities. Early adoption is permitted. The Company adopted ASU 2019-12 on January 1, 2021 and the standard did not have a material impact on its condensed financial statements and related disclosures. Recently Issued Accounting Standards There were no recently issued accounting standards that the Company believes have had or will have a material impact on its financial position or results of operations.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1 —Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. Level 2 —Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability. Level 3 —Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). No transfers between levels have occurred during the periods presented. There were no assets or liabilities measured at fair value on a recurring basis as of either March 31, 2022 or December 31, 2021. As further described in Note 7, the Company issued a convertible promissory note in August 2020. The convertible promissory note contained certain features that met the definition of a derivative and were required to be bifurcated. The Company accounted for these as a single derivative comprising all the features requiring bifurcation. The fair value of the derivative liability was estimated using a scenario-based analysis comparing the probability-weighted present value of the convertible promissory note payoff at maturity with and without the bifurcated features. The Company considered possible outcomes available to the noteholders, including various financing dissolution scenarios. In addition, the probabilities applied to various scenarios, the time to liquidity for each scenario, and the discount rate were the key unobservable inputs. The following table summarizes information about the significant unobservable inputs used in the fair value measurements for the derivative liability: March 19, 2021 Probability of financing 100 % Probability of dissolution — Time to liquidity (years) — Discount rate 7.6 % The Company adjusted the carrying value of the derivative liability within the convertible promissory note to the estimated fair value at each reporting date, with any related increases or decreases in the fair value recorded as change in fair value of derivative liability in the statements of operations and comprehensive loss. For the three months ended March 31, 2021, the Company recognized $ 0.2 million of other income in the statements of operations and comprehensive loss related to increases in the fair value of the embedded derivative liability. On March 19, 2021, in connection with the closing of the Series B convertible preferred stock financing, the convertible promissory note (including accrued interest) and derivative liability converted into 2,805,850 shares of Series B-2 convertible preferred stock. As a result of the conversion, the Company recorded a loss on extinguishment of convertible promissory notes of $ 0.8 million in other expense in the condensed statements of operations and comprehensive loss for the three months ended March 31, 2021, which included the derecognition of unamortized debt issuance costs. The following table provides a reconciliation of the fair value of the derivative liability using Level 3 significant unobservable inputs (in thousands): Derivative Liability Fair value at December 31, 2020 $ ( 1,604 ) Change in fair value of embedded derivative liability ( 205 ) Reclassification of derivative liability into convertible preferred stock resulting from conversion of convertible promissory note 1,809 Fair value at March 31, 2021 $ —

Grant Agreement

Grant Agreement	3 Months Ended
	Mar. 31, 2022
Grant Agreement [Abstract]
Grant Agreement	4. Grant Agreement Bill & Melinda Gates Foundation Grant Agreement In support of the Company’s development of its IVX-411 COVID-19 vaccine for pandemic use, in September 2020, the Company entered into the grant agreement (the “Grant Agreement”) with the Bill & Melinda Gates Foundation (“BMGF”), under which it was awarded a grant totaling up to $ 10.0 million (the “Grant”). The Grant supported development activities, including the Company’s regulatory filing preparations and its Phase 1/2 clinical trial of IVX-411. The Grant terminated in accordance with its terms on March 31, 2022. Concurrent with and in connection with the Grant Agreement, the Company entered into a Global Access Commitments Agreement (“GACA”) with BMGF. Under the terms of the GACA, among other things, the Company agreed to make a certain amount of its IVX-411 COVID-19 vaccine for pandemic use available and accessible at affordable pricing to people in certain low- and middle-income countries, if the vaccine is commercialized. Payments received in advance that were related to future performance were deferred and recognized as revenue when the research and development activities were performed. Cash payments received under the Grant Agreement were restricted as to their use until eligible expenditures were incurred. At March 31, 2022, the Company had no restricted cash and deferred revenue, and at December 31, 2021, had $ 0.6 million of restricted cash and deferred revenue, representing funds received from BMGF and the Company's estimate of costs to be reimbursed and revenue to be recognized, respectively, in the next twelve months under the Grant Agreement. During the three months ended March 31, 2021, the Company received $ 2.7 million in funding from BMGF. The Company received no funding from BMGF during the three months ended March 31, 2022. During the three months ended March 31, 2022 and 2021, the Company recognized revenue from the Grant Agreement of $ 0.6 million and $ 2.0 million, respectively. The Company had received the full $ 10.0 million in funding under the Grant Agreement as of December 31, 2021, and through March 31, 2022, the Company has recognized $ 10.0 million in revenue since the inception of the Grant Agreement.

Additional Balance Sheet Inform

Additional Balance Sheet Information	3 Months Ended
	Mar. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Additional Balance Sheet Information	5. Additional Balance Sheet Information Accrued and other current liabilities consist of the following (in thousands): As of March 31, 2022 As of December 31, 2021 Taxes payable $ 35 $ — Accrued paid time off 480 342 Accrued bonus 729 2,216 Other accrued liabilities 5,759 1,977 Accrued 401k 213 156 ESPP liability 232 66 Total accrued and other current liabilities $ 7,448 $ 4,757

License Agreements

License Agreements	3 Months Ended
	Mar. 31, 2022
License Agreements [Abstract]
License Agreements	6. License Agreements License Agreement with the National Institutes of Health The Company is a party to a non-exclusive patent license agreement (as amended, the “NIH Agreement”) with a U.S. government entity, the National Institutes of Health, represented by National Institute of Allergy and Infectious Disease (“NIAID”), which was originally entered into in June 2018. Under the NIH Agreement, the Company obtained a non-exclusive, worldwide, royalty-bearing, sublicensable license under certain NIAID patent rights, and transfer of know-how and biological materials for use in adjuvanted or non-adjuvanted vaccines for the prevention, cure, or treatment of RSV and metapneumovirus (hMPV) infection in humans. Under the NIH Agreement, the Company is required to use commercially reasonable efforts to meet certain specified development, sales and regulatory milestones related to the licensed products within specified time periods. In consideration of the rights granted to the Company under the NIH Agreement, the Company paid a licensing fee upon execution of the NIH Agreement of $ 100,000 , and will pay annual minimum royalty payments starting in the second year after the initial sale of each licensed product which can be credited against any earned royalties due for sales made in the year. The Company is obligated to pay aggregate potential milestone payments of up to $ 8.6 million with respect to future development and commercial milestones. Additionally, the Company has agreed to pay a tiered royalty of a low single digit percentage on net sales of all products applicable to the license. Additional royalties would be due in connection with sublicenses. The Company’s royalty obligations continue for each licensed product for so long as licensed patent rights exist and have not expired, been revoked, lapsed, or held unenforceable. The NIH Agreement will terminate upon the last expiration of the patent rights or the Company may terminate the entirety of the agreement upon discontinuation of development or sales of licensed products and provision of written notice thereof to NIH. The Company made no payments associated with the license during the three months ended March 31, 2022, and during the three months ended March 31, 2021, the Company paid a negligible amount in fees associated with the license, which were recorded as research and development expenses. License Agreements with University of Washington License Agreement with respect to RSV and Other Pathogens The Company is a party to an exclusive license agreement with the University of Washington (“UW”), originally entered into in June 2018 (as amended, the “UW 2018 Agreement”). Under the UW 2018 Agreement, UW granted the Company an exclusive, worldwide, royalty-bearing, sublicensable license under certain UW patents to make, use, sell, offer to sell, import, and otherwise exploit any product covered by the licensed patents, or licensed products, for the prophylactic and/or therapeutic treatment of RSV infection and five other infectious diseases. UW also granted the Company a non-exclusive, worldwide license under certain know-how related to the licensed patents. The licensed patents and know-how generally relate to computationally designed nanoparticles and vaccines based upon such designs, and relate to the Company’s proprietary two-component virus-like-particle technology. The Company’s rights and obligations under the UW 2018 Agreement are subject to certain U.S. government rights, certain global access commitment rights for humanitarian purposes to BMGF, certain rights to Howard Hughes Medical Institute ("HHMI"), and certain other limited rights retained by UW. The Company issued 192,276 shares of common stock on August 1, 2018 in exchange for the UW 2018 Agreement’s exclusive license. The shares issued were recorded at their estimated fair value, which is de minimis, with the related expense classified as research and development in 2018. Under the UW 2018 Agreement, the Company is required to use commercially reasonable efforts to meet certain specified development, sales and regulatory milestones related to the licensed products within specified time periods. In consideration of the rights granted to the Company under the UW 2018 Agreement, the Company is required to pay an annual maintenance fee in the mid four figures starting in 2020. Additionally, the Company is required to pay minimum annual royalties following the first year after commercial sale of each licensed product. There are milestone payments due upon the completion of certain development, regulatory, and commercial milestones for licensed products in the future. The aggregate potential milestone payments for future development, regulatory, and sales-based milestones are $ 1.35 million per indication, up to a maximum of $ 8.1 million in total milestone payments. Additionally, the Company has agreed to pay a royalty of a low single digit percentage on net sales of all licensed products. Additional royalties would be due in connection with sublicenses. The Company’s royalty obligations continue for each licensed product for so long as licensed patent rights exist and have not expired, been revoked, lapsed, or held unenforceable. Unless terminated earlier, the UW 2018 Agreement will remain in effect until all licensed patent rights have terminated and all obligations due to UW have been fulfilled. The last-to-expire licensed patent, if issued, is expected to expire in 2041, subject to any adjustment or extension of patent term that may be available. UW can terminate the UW 2018 Agreement if the Company breaches or fails to perform one of its material duties under the UW 2018 Agreement and the Company is unable to remedy the default within an agreed upon time period that can be extended by UW. The Company may terminate the UW 2018 Agreement at will with prior written notice to UW. Option and License Agreement with Respect to COVID-19 The Company is also a party to an option and license agreement, originally entered into in July 2020 (as amended, the “UW 2020 Agreement”). Under the UW 2020 Agreement, UW granted the Company a non-exclusive, worldwide (excluding South Korea), sublicensable license under certain UW patents to make, use, sell, offer to sell, import, or otherwise exploit any product covered by the licensed patents for the prophylactic and/or therapeutic treatments of SARS-CoV-2 infection. Under an option exercised by the Company, UW granted the Company an exclusive license under the licensed patents for the United States, Canada, Mexico, and Europe (including Switzerland and the United Kingdom) starting in 2025. UW also granted the Company a non-exclusive, worldwide license under certain know-how related to the licensed patents. The licensed patents and know-how generally relate to computationally designed nanoparticles and vaccines based upon such designs. The Company’s rights and obligations under the UW 2020 Agreement are subject to certain U.S. government rights, certain global access commitment rights for humanitarian purposes to BMGF, certain rights to HHMI, and certain other limited rights retained by UW. Under the UW 2020 Agreement, the Company is required to use commercially reasonable efforts to meet certain specified development, sales and regulatory milestones related to the licensed products within specified time periods. The Company has agreed to pay a royalty of a low single digit percentage on net sales of all products applicable to the license. However, the Company will not be required to pay royalties on net sales of any licensed product under the UW 2020 Agreement if the Company is required to pay royalties on net sales under the UW 2018 Agreement. Additional royalties would be due in connection with sublicenses and milestones. The Company’s royalty obligations continue for each licensed product for so long as licensed patent rights exist and have not expired, been revoked, lapsed, or held unenforceable. Unless terminated earlier, the UW 2020 Agreement will remain in effect until all licensed patent rights have terminated and all obligations due to UW have been fulfilled. The last-to-expire licensed patent, if issued, is expected to expire in 2041, subject to any adjustment or extension of patent term that may be available. UW can terminate the UW 2020 Agreement if the Company breaches or fails to perform one of its material duties under the UW 2020 Agreement and the Company is unable to remedy the default within an agreed upon time period that can be extended by UW. The Company may terminate the UW 2020 Agreement at will with prior written notice to UW. During the three months ended March 31, 2022 and 2021, the Company paid negligible amounts in fees associated with the 2018 and 2020 Agreements. License Agreement with Respect to Influenza The Company is a party to a license agreement with UW ("UW Flu License Agreement") entered into in September 2021. Pursuant to the UW Flu License Agreement, UW granted the Company a non-exclusive, worldwide, royalty-bearing, sublicensable (subject to certain restrictions) license under certain UW patents to make, use, sell, offer to sell, import, and otherwise exploit any product covered by the licensed patents ("Licensed Flu Products"), for the prophylactic and/or therapeutic treatment of influenza. UW also granted the Company a non-exclusive, worldwide license to use certain know-how related to the licensed patents. The licensed patents and know-how generally relate to computationally designed nanoparticles and vaccines based upon such designs, and relate to the Company's proprietary two-component virus-like-particle technology and nanoparticle-based influenza virus vaccines. The United States federal government and HHMI have similar rights under the UW Flu License Agreement and the UW 2018 Agreement described above in “License Agreement with respect to RSV and Other Pathogens". The Company is obligated to use commercially reasonable efforts to commercialize Licensed Flu Products, and to initiate a clinical trial with respect to such Licensed Flu Products by a specified date in 2025. If the Company is unable to initiate a clinical trial by the specified date and cannot agree with UW to modify such obligation or does not cure by meeting such obligation, then UW may terminate the UW Flu License Agreement. Under the UW Flu License Agreement, the Company paid UW a one-time upfront license fee, and after September 2023 and for the remainder of the term of the UW Flu License Agreement, the Company is required to pay tiered minimum annual fees ranging from the mid four figures to the mid five figures, with such fees creditable against royalty payments. The Company is required to pay UW up to an aggregate of $ 6.4 million for payments related to development and commercial milestones. The Company is also required to pay UW a fixed, low single-digit percentage royalty on net sales of Licensed Flu Products by the Company and its sublicensees, subject to certain reductions if the Company is required to pay for third-party intellectual property rights in order to commercialize the Licensed Flu Products. The Company is not obligated to pay duplicate royalties on net sales of any Licensed Flu Products if the Company is already required to pay a royalty on such net sales under the UW 2018 Agreement and the UW 2020 Agreement. Unless terminated earlier, the UW Flu License Agreement will remain in effect until all licensed patent rights have terminated and all obligations due to UW have been fulfilled. The last-to-expire licensed patent, if issued, is expected to expire in 2041 , subject to any adjustment or extension of patent term that may be available. UW can terminate the UW Flu License Agreement if the Company breaches or fails to perform one of its material duties under the UW Flu License Agreement and is unable to remedy the default within an agreed upon time period that can be extended by UW. The Company can terminate the UW Flu License Agreement at will with prior written notice to UW. During the three months ended March 31, 2022, the Company paid a negligible amount in fees associated with the UW Flu License Agreement. License Agreement with the University of Texas The Company is a party to an exclusive patent license agreement with the University of Texas at Austin (“UT”) with respect to its hMPV antigen utilized in the IVX-A12 program (the “UT Agreement”). The UT Agreement was entered into in June 2021. Under the UT Agreement, UT granted the Company an exclusive, worldwide, royalty-bearing, sublicensable license under certain patent rights, to use licensed know-how for prevention, cure, amelioration or treatment of respiratory disease caused by metapneumovirus infection in all vaccine fields, excluding up to one mRNA-based vaccine. The Company is obligated to pay aggregate potential milestone payments of up to $ 4.6 million with respect to future development and commercial milestones. Unless terminated earlier, the UT Agreement will remain in effect until all the licensed patent rights have expired. The Company may terminate the UT Agreement with prior written notice to UT. UT may terminate the UT Agreement in whole or in part, or narrow the vaccine field, reduce the territory, or convert the license from exclusive to non-exclusive if the Company: (i) fails to meet its payment obligations, (ii) commits an uncured breach, (iii) commits three or more cured breaches within a specified time period, (iv) challenges the validity, enforceability, or scope of the licensed patent rights, or (v) undergoes certain insolvency-related events. During the three months ended March 31, 2022, the Company paid a negligible amount in fees associated with the UT Agreement.

Convertible Promissory Note

Convertible Promissory Note	3 Months Ended
	Mar. 31, 2022
Temporary Equity Disclosure [Abstract]
Convertible Promissory Note	7. Convertible Promissory Note In August 2020, the Company issued a $ 6.5 million convertible promissory note (“Convertible Promissory Note”). The Convertible Promissory Note accrued interest at a rate of 6 % a year with a maturity date two years from issuance. The Convertible Promissory Note could be converted or redeemed as follows (i) automatically converted in a qualified Series B financing transaction from which the Company would receive total gross proceeds of not less than $ 5.0 million at a conversion price equal to 85 % of the per share price paid by investors for such securities, (ii) automatically converted upon initial public offering at a conversion price equal to 85% of the per share price off common stock in the initial public offering, (iii) optionally converted into Series A-3 convertible preferred stock if a change in control, IPO, or qualified Series B financing had not occurred prior to the maturity date at a price equal to an amount determined by dividing $ 140 million by the fully diluted capitalization of the Company at the time of conversion, or (iv) repaid upon a change in control for an amount equal to the issue price plus accrued and unpaid interest or an amount as would have been payable if the noteholders had optionally converted into shares of Series A-3 convertible preferred stock. The Convertible Promissory Note was converted in March 2021 in connection with the Series B financing. The Convertible Promissory Note was accounted for in accordance with ASC 470-20, Debt with Conversion and Other Options (“ASC 470-20”) and ASC 815-15, Derivatives and Hedging - Embedded Derivatives (“ASC 815-15”). Under ASC 815-15, an embedded feature is required to be bifurcated if all three conditions are met: (1) economic characteristics and risks of the embedded derivative are not clearly and closely related to the economic characteristics and risks of the host contract, (2) the hybrid instrument is not remeasured at fair value under otherwise applicable GAAP with changes in fair value reported in earnings as they occur, and (3) a separate instrument which the same terms as the embedded derivative would be considered a derivative instrument subject to derivative accounting (the initial net investment for the hybrid instrument should not be considered to be the initial net investment for the embedded derivative). The Company bifurcated certain features that were required to be accounted for separately as a single embedded derivative. The initial fair value of this derivative of $ 1.8 million was recorded as a liability, and as a reduction to the carrying value of the Convertible Promissory Note. The Company also incurred a negligible amount of issuance costs related to the Convertible Promissory Note, which were also recorded as a reduction to the Convertible Promissory Note on the condensed balance sheet. The debt discount comprised the initial fair value of the derivative liability and the issuance costs, and was amortized using the effective interest method over the two-year contractual term of the Convertible Promissory Note and presented as a direct reduction of the debt liability. The debt discount was being amortized at an effective interest rate of 23.8 %. Interest expense incurred in connection with the Convertible Promissory Note consisted of the following (in thousands): Three Months Ended March 31, 2021 Coupon interest at 6% $ 86 Accretion of discount and amortization of issuance costs 177 Total interest expense on Convertible Promissory Note $ 263 On March 19, 2021, in connection with the closing of the Series B convertible preferred stock financing, the Convertible Promissory Note (including accrued interest) and derivative liability converted into 2,805,850 shares of Series B-2 convertible preferred stock at an issuance price of $ 2.39846 per share. As a result of the conversion, the Company recorded a loss on extinguishment of convertible promissory notes of $ 0.8 million in other expense in the condensed statements of operations and comprehensive loss for the three months ended March 31, 2021, which included the unamortized debt issuance costs.

Leases

Leases	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Leases	8. Leases In January 2020, and amended in March 2020, the Company entered into a lease agreement for office and laboratory space in Seattle, Washington. The lease agreement is twelve months and provides for renewal options. The monthly base rent is approximately $ 16,000 . The lease agreement is considered short-term and therefore, no right-of-use asset or lease liability has been recorded. In December 2021, the Company entered into a lease agreement for corporate office and laboratory space in Seattle, Washington. The Company took possession of certain leased space at various dates in January 2022 and March 2022. The lease agreement expires in December 2027 and provides for a one-time option to extend for a period of five additional years. The lease agreement provides the Company with an allowance for tenant improvements of $ 5.3 million that will be reimbursed to the Company or paid on its behalf as construction of improvements occurs. The monthly base rent will be $ 0.2 million for the first year and will increase by 3.0 % per year over the initial term. In addition, the Company is obligated to pay for common area maintenance and other costs. Under the terms of the lease agreement, the Company is required to maintain a standby letter of credit of $ 1.1 million at the execution of the lease agreement, reduced to $ 0.9 million at the first anniversary, and further reduced to $ 0.7 million at the second anniversary of the lease. Classification of ROU assets and lease liabilities and the weighted-average remaining lease term and discount rate associated with operating leases are as follows ($ in thousands): As of March 31, 2022 As of December 31, 2021 ROU assets: ROU assets - operating leases $ 3,309 $ — Lease liabilities: Current portion of operating lease liabilities 530 — Noncurrent portion of operating lease liabilities 2,964 — Total lease liabilities $ 3,494 $ — Weighted-average remaining lease term (in years): Operating leases 5.8 — Weighted-average discount rate: Operating leases 8.0 % — The components of lease costs are as follows (in thousands): Three Months Ended 2022 2021 Operating lease costs $ 185 $ — Short-term lease costs 141 14 Total lease costs $ 326 $ 14 The maturities of lease liabilities and reconciliation to the present value of lease liabilities are as follows (in thousands): As of March 31, 2022 2022 $ — 2023 2,137 2024 2,201 2025 2,267 2026 2,335 Thereafter 2,405 Total undiscounted lease payments 11,345 Less: lease incentives ( 5,301 ) Less: imputed interest ( 2,550 ) Total lease liabilities 3,494 Less: current lease liabilities ( 530 ) Lease liabilities, net of current portion $ 2,964

Convertible Preferred Stock and

Convertible Preferred Stock and Stockholders' Equity (Deficit)	3 Months Ended
	Mar. 31, 2022
Stockholders' Equity Note [Abstract]
Convertible Preferred Stock and Stockholders' Equity (Deficit)	. Convertible Preferred Stock and Stockholders’ Equity (Deficit) Convertible Preferred Stock Prior to its conversion into common stock in connection with the Company’s IPO in August 2021, the Company’s convertible preferred stock was classified as temporary equity on the Company’s balance sheets in accordance with authoritative guidance. Convertible preferred stock authorized and issued and its principal terms as of March 31, 2021 consisted of the following ($ amounts in thousands): Shares Shares Issued Shares of Aggregate Carrying Series A-1 49,193,959 49,193,959 11,837,711 $ 47,300 $ 46,917 Series A-2 4,949,794 4,949,794 1,191,082 $ 3,807 $ 4,150 Series B-1 32,958,612 32,958,612 7,930,924 $ 93,000 $ 92,654 Series B-2 2,805,850 2,805,850 675,181 $ 6,730 $ 7,917 Total 89,908,215 89,908,215 21,634,898 $ 150,837 $ 151,638 In February 2021, the Company triggered a milestone closing associated with its Series A-1 convertible preferred stock resulting in the issuance of 21,944,874 shares. In March 2021, before the Company effected a 1-for-4.1557 reverse stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each series of the Company’s convertible preferred stock in July 2021, the Company entered into a convertible preferred stock purchase agreement for the issuance of 35,764,462 shares of Series B convertible preferred stock, $ 0.0001 par value per share, of which 32,958,612 shares of Series B-1 and 2,805,850 shares of Series B-2 were issued. The Series B convertible preferred stock financing resulted in net cash proceeds of $ 92.7 million, net of $ 0.35 million in issuance costs from the sale of 32,958,612 shares of Series B-1 convertible preferred stock at a price of $ 2.82172 per share. In addition, the Convertible Promissory Note of $ 6.5 million that the Company issued in August 2020, including accrued interest as of the date of conversion of $ 0.2 million, was converted into 2,805,850 shares of Series B-2 convertible preferred stock on March 19, 2021 at 85 % of the offering’s share price. In connection with the Company’s IPO in August 2021, all outstanding shares of the convertible preferred stock converted into 21,634,898 shares of common stock and the related carrying value was reclassified to common stock and additional paid-in capital. There were no shares of convertible preferred stock outstanding as of the closing of the IPO. In addition, on August 2, 2021, the Company amended and restated its certificate of incorporation to authorize 500,000,000 shares of common stock and 50,000,000 shares of preferred stock, which shares of preferred stock are currently undesignated. The Company does not have any outstanding preferred stock as of March 31, 2022. Common Stock As of March 31, 2022 and December 31, 2021, of the Company's 500,000,000 authorized shares of common stock, 39,724,867 and 39,429,103 shares were issued, respectively. As of March 31, 2022 and December 31, 2021, shares outstanding, which excludes common stock issued from the early exercise of unvested stock options, were 39,524,526 and 39,175,279 , respectively. Equity Incentive Plans In 2017, the Company established an equity incentive plan (the “2017 Plan”) under which incentives may be granted to officers, employees, directors, consultants and advisors. Awards under the 2017 Plan consisted of restricted stock and incentive and non-qualified stock options to purchase shares of common stock of the Company. During 2021, the Company’s stockholders approved the 2021 Incentive Plan (the “2021 Plan”), which became effective in July 2021. The 2021 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock, dividend equivalents, restricted stock units ("RSU") and other stock or cash-based awards. The number of shares of the Company’s common stock initially reserved for issuance under the 2021 Plan is 4,600,000 shares; plus the shares of common stock remaining available for issuance under the 2017 Plan as of the effective date of the 2021 Plan, as well as any shares subject to outstanding awards under the 2017 Plan as of the effective date of the 2021 Plan that become available for issuance under the 2021 Plan thereafter in accordance with its terms. The number of shares initially available for issuance increases annually on January 1 of each calendar year beginning in 2022 and ending in and including 2031, equal to the lesser of (A) 5% of the shares outstanding on the final day of the immediately preceding calendar year and (B) a smaller number of shares as determined by our board of directors. The reserve for the 2021 Plan increased by 5 %, or 1,971,455 shares, effective January 1, 2022. No more than 50,000,000 shares of common stock may be issued under the 2021 Plan upon the exercise of incentive stock options. The 2021 Plan is administered by the Board of Directors of the Company or a committee appointed by the Board of Directors, which determines the types of awards to be granted, including the number of shares subject to the awards, the exercise price and the vesting schedule. All option and service-based RSU awards are subject to a time-based vesting period which will generally be four years . Performance-based RSU awards are subject to vesting conditions based on the achievement of specified milestones related to development of vaccine candidates. Certain option and RSU awards provide for accelerated vesting if there is a change in control or if other contractually specified contingencies are met. The term of stock options granted under the 2021 Plan cannot exceed ten years (or five years in the case of incentive stock options granted to certain significant stockholders). Options shall not have an exercise price less than 100 % of the fair market value of the Company’s common stock on the grant date (or 110 % in the case of incentive stock options granted to certain significant stockholders), except with respect to certain substitute awards granted in connection with a corporate transaction. Common stock reserved for future issuance consisted of the following: As of March 31, 2022 Common stock options and restricted stock units granted and outstanding 8,525,522 Shares available for issuance under the equity incentive plans 3,771,600 Shares available for issuance under the 2021 Employee Stock Purchase Plan 777,685 Total common stock reserved for issuance 13,074,807 A summary of the status of the options issued under the Company’s equity incentive plans as of March 31, 2022, and information with respect to the changes in options outstanding is as follows : Options Weighted Average Exercise Weighted Average Remaining Aggregate Balance at December 31, 2021 6,591,727 $ 8.04 9.26 Authorized increase in plan shares — — — — Granted 1,258,140 17.48 — — Exercised (including early) ( 295,764 ) 0.94 — $ 4,290,213 Balance at March 31, 2022 7,554,103 $ 9.89 9.19 $ 11,365,470 Vested and expected to vest as of 7,554,103 $ 9.89 9.19 $ 11,365,470 Vested and exercisable at 1,563,412 $ 5.99 9.00 $ 3,058,199 Exercisable options in the table above reflect the number of options vested as of the date reported. The 2021 Plan permits early exercises of options. Cash received for early exercise of unvested options is recognized as an other noncurrent liability in the accompanying balance sheet and totaled $ 0.1 million at March 31, 2022. The aggregate intrinsic value in the table above is calculated as the difference between the exercise price of the underlying options and the fair value of the Company’s common stock for all options that were in-the-money as of March 31, 2022. During the three months ended March 31, 2022, the Company granted 1,258,140 options, with a grant date fair value of $16.5 million. The weighted-average grant date fair value of employee option grants during the three months ended March 31, 2022 was $ 13.08 per share. A summary of the status of RSUs issued under the Company’s equity incentive plans as of March 31, 2022, and information with respect to the changes in RSUs outstanding is as follows: Service-based RSUs Performance-based RSUs Units Weighted Average Grant-Date Fair Value Units Weighted Average Grant-Date Fair Value Nonvested at December 31, 2021 388,500 $ 25.96 — $ — Granted 522,919 $ 17.60 60,000 $ 18.74 Nonvested at March 31, 2022 911,419 $ 21.16 60,000 $ 18.74 Expected to vest at March 31, 2022 911,419 $ 21.16 — $ — Employee Stock Purchase Plan During 2021, the Company’s stockholders approved the 2021 Employee Stock Purchase Plan (the “ESPP”), which became effective in July 2021. The ESPP permits eligible employees who elect to participate in an offering under the ESPP to have up to 15% of their eligible earnings withheld, subject to certain limitations, to purchase shares of common stock pursuant to the ESPP. The price of common stock purchased under the ESPP is equal to 85% of the lower of the fair market value of the common stock at the commencement date of each offering period or the relevant date of purchase. The number of shares of common stock initially reserved for issuance under the ESPP is 400,000 shares. The number of shares of common stock reserved for issuance under the ESPP increased on January 1, 2022 and each January 1 thereafter through January 1, 2031, in an amount equal to the lower of (1) 1 % of the aggregate number of shares of common stock of the Company outstanding on the final day of the immediately preceding calendar year and (2) such smaller number of shares of common stock as determined by the Board, provided that no more than 15,000,000 shares of our common stock may be issued under the ESPP. The reserve for the ESPP increased by 1 % or 394,291 shares, on January 1, 2022. As of March 31, 2022, 16,606 shares have been purchased by employees under the ESPP. Stock-based compensation expense related to the ESPP for the three months ended March 31, 2022 and 2021 was $ 0.1 million and $ 0 , respectively. Stock-Based Compensation Expense Stock-based compensation expense for all equity awards and the ESPP has been reported in the condensed statements of operations and comprehensive loss as follows (in thousands): Three Months Ended 2022 2021 Research and development $ 1,687 $ 113 General and administrative 2,863 163 Total $ 4,550 $ 276 The Company recognizes compensation expense for options and RSU awards granted to employees and the board of directors based on their grant date fair value. The compensation expense is recognized over the vesting period of 4 years on a straight-line basis. The fair value of each stock option granted was determined using the Black-Scholes option pricing model. The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee and nonemployee stock option grants issued during years ended were as follows: Three Months Ended 2022 2021 Risk-free rate of interest 1.43 %- 2.12 % 0.53 %- 0.64 % Expected term (years) 5.77 - 6.08 years 5.48 - 6.12 years Expected stock price volatility 89.3 % - 118.1 % 86.0 % - 87.9 % Dividend yield 0 % 0 % As of March 31, 2022, the unrecognized compensation cost related to outstanding stock options and RSU awards was $ 52.3 million and $ 17.3 million, respectively and is expected to be recognized as expense over a weighted-average period of approximately 3.38 years.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	. Income Taxes There was no provision for income taxes recorded during the three months ended March 31, 2022 or 2021. The Company’s deferred tax assets continue to be reduced by a full valuation allowance. The Company is subject to income taxes in the United States and its effective tax rate is calculated quarterly based upon current assumptions relating to the full year’s estimated operating results and various tax-related items. Each quarter an estimate of the annual effective tax rate is updated should the Company revise its forecast of earnings based upon its operating results. If there is a change in the estimated effective annual tax rate, a cumulative adjustment is made. The Company's effective tax rate was 0 % for the three months ended March 31, 2022 and 2021. The difference between the effective tax rate of 0 % and the U.S. federal statutory rate of 21 % for the three months ended March 31, 2022 and 2021 was primarily due to recognizing a full valuation allowance on deferred tax assets. As of March 31, 2022, the Company determined that, based on an evaluation of the four sources of taxable income that may be available under the tax law to realize a tax benefit for deductible temporary differences and carryforwards, and all available evidence, both positive and negative, including the Company's latest forecasts and cumulative losses in recent years, it was more likely than not that none of its deferred tax assets would be realized and therefore the Company continued to record a full valuation allowance. No current tax liability or expense has been recorded in the financial statements.

Employee Saving Plan

Employee Saving Plan	3 Months Ended
	Mar. 31, 2022
Postemployment Benefits [Abstract]
Employee Saving Plan	11. Employee Savings Plan The Company has a defined contribution 401(k) savings plan for those employees who meet minimum eligibility requirements. Under the terms of the plan, eligible employees may contribute up to 90 % of their annual compensation to the plan, subject to Internal Revenue Service limitations. The Company may also, at its sole discretion, make contributions to the plan. The Company did not make any contributions to the plan during the three months ended March 31, 2022 or 2021.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements as of March 31, 2022 and for the three months ended March 31, 2022 and 2021 have been prepared in conformity with generally accepted accounting principles (“GAAP”) in the United States of America for interim financial information and pursuant to Article 10 of Regulation S-X of the Securities Act of 1933, as amended (the “Securities Act”). Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. These unaudited condensed financial statements include only normal and recurring adjustments that the Company believes are necessary to fairly state the Company’s financial position and the results of its operations and cash flows. The results for the three months ended March 31, 2022 are not necessarily indicative of the results expected for the full fiscal year or any subsequent interim period. The condensed balance sheet at December 31, 2021 has been derived from the audited financial statements at that date but does not include all disclosures required by GAAP for complete financial statements. Because all of the disclosures required by GAAP for complete financial statements are not included herein, these unaudited condensed financial statements and the notes accompanying them should be read in conjunction with the Company’s audited financial statements for the year ended December 31, 2021 included in the Annual Report on Form 10-K (the "Annual Report") that the Company filed with the Securities and Exchange Commission (the “SEC”) on March 30, 2022.
Use of Estimates	Use of Estimates The Company’s significant accounting policies are described in Note 2, “Summary of significant accounting policies,” of the Company’s audited financial statements for the year ended December 31, 2021 included in the Annual Report. There have been no material changes to the significant accounting policies previously disclosed in those audited financial statements. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including expenses, clinical trials and research and development costs, will depend on future developments that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain or treat COVID-19, as well as the economic impact on local, regional, national and international markets. The Company has considered potential impacts arising from the COVID-19 pandemic and is not presently aware of any events or circumstances that would require the Company to update its estimates, judgments or revise the carrying value of its assets or liabilities.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The accounting guidance defines fair value, establishes a consistent framework for measuring fair value, and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is defined as an exit price representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. The carrying amounts of all cash, restricted cash, prepaid expenses and other assets, accounts payable, and accrued and other current liabilities are considered to be representative of their respective fair values due to their short maturities.
Derivative Liability, Convertible Notes Discount and Amortization	Derivative Liability, Convertible Notes Discount and Amortization The Company’s convertible note (see Note 7) had conversion and redemption features that met the definition of an embedded derivative and were therefore subject to bifurcation and derivative accounting. The initial recognition of the fair value of the derivative resulted in a discount to the convertible note, with a corresponding derivative liability. The discount to the convertible note was amortized using the effective interest method. The amortization of the discount is included in interest and other income (expense) in the statements of operations and comprehensive loss. The derivative liability related to these features was recorded at estimated fair value and remeasured on a recurring basis. Any changes in fair value were reflected as change in fair value of derivative liability in the statements of operations and comprehensive loss at each reporting date while such instruments were outstanding. The derivative liability was settled in March 2021 upon conversion of the underlying convertible note into Series B convertible preferred stock, resulting in a loss on extinguishment of the convertible promissory note.
Leases	Leases At the inception of a contractual arrangement, the Company determines whether the contract contains a lease by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration over a period of time. If both criteria are met, the Company records the associated lease liability and corresponding right-of-use ("ROU") asset upon commencement of the lease using the implicit rate or a discount rate based on a credit-adjusted secured borrowing rate commensurate with the term of the lease. The Company additionally evaluates leases at their inception to determine if they are to be accounted for as an operating lease or a finance lease. A lease is accounted for as a finance lease if it meets one of the following five criteria: the lease has a purchase option that is reasonably certain of being exercised, the present value of the future cash flows is substantially all of the fair market value of the underlying asset, the lease term is for a significant portion of the remaining economic life of the underlying asset, the title to the underlying asset transfers at the end of the lease term, or if the underlying asset is of such a specialized nature that it is expected to have no alternative uses to the lessor at the end of the term. Leases that do not meet the finance lease criteria are accounted for as an operating lease. Operating lease assets represent a right to use an underlying asset for the lease term and operating lease liabilities represent an obligation to make lease payments arising from the lease. Operating lease liabilities with a term greater than one year and their corresponding ROU assets are recognized on the balance sheet at the commencement date of the lease based on the present value of lease payments over the expected lease term. Certain adjustments to the ROU asset may be required for items such as initial direct costs paid or incentives received. As the Company’s leases do not typically provide an implicit rate, the Company utilizes the appropriate incremental borrowing rate, determined as the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term and in a similar economic environment. Lease cost is recognized on a straight-line basis over the lease term and variable lease payments are recognized as operating expenses in the period in which the obligation for those payments is incurred. Variable lease payments primarily include common area maintenance, utilities, real estate taxes, insurance, and other operating costs that are passed on from the lessor in proportion to the space leased by the Company. The Company has elected the practical expedient to not separate lease and non-lease components.
Liability for Early Exercise of Stock Options	Liability for Early Exercise of Stock Options Certain individuals were granted the ability to early exercise their stock options. The shares of common stock issued from the early exercise of unvested stock options are restricted and continue to vest in accordance with the original vesting schedule. The Company has the option to repurchase any unvested shares at the original purchase price upon any voluntary or involuntary termination. The shares purchased by the employees and non-employees pursuant to the early exercise of stock options are not deemed, for accounting purposes, to be outstanding until those shares vest. The cash received in exchange for exercised and unvested shares related to stock options granted is recorded as a liability for the early exercise of stock options on the accompanying balance sheets and will be reclassified as common stock and additional paid-in capital as the shares vest. Unvested shares issued under early exercise provisions subject to repurchase by the Company totaled 200,341 and 253,824 shares as of March 31, 2022 and December 31, 2021, respectively. As of March 31, 2022 and December 31, 2021, the Company recorded $ 0.1 million and $ 0.2 million respectively, associated with shares issued with repurchase rights as other noncurrent liabilities in the accompanying condensed balance sheets.
Commitments and Contingencies	Commitments and Contingencies The Company recognizes a liability with regard to loss contingencies when it believes it is probable a liability has been incurred, and the amount can be reasonably estimated. If some amount within a range of loss appears at the time to be a better estimate than any other amount within the range, the Company accrues that amount. When no amount within the range is a better estimate than any other amount the Company accrues the minimum amount in the range. In the event the Company becomes subject to claims or suits arising in the ordinary course of business, the Company would accrue a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. The Company has not recorded any such liabilities at either March 31, 2022 or December 31, 2021.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss attributable to common stockholders by the weighted- average number of shares of common stock outstanding for the period. Diluted net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock and common stock equivalents outstanding for the period. Common stock equivalents are only included when their effect is dilutive. The Company’s potentially dilutive securities include outstanding stock options under the Company’s equity incentive plan and have been excluded from the computation of diluted net loss per share as they would be anti-dilutive to the net loss per share. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position. The following tables summarize the computation of the basic and diluted net loss per share (in thousands, except share and per share data): Three Months Ended 2022 2021 Numerator: Net loss $ ( 23,533 ) $ ( 5,851 ) Denominator: Weighted-average common shares outstanding, basic and 39,602,146 3,674,126 Less: Weighted average unvested common stock ( 200,341 ) ( 904,164 ) Weighted average shares used to compute net loss per 39,401,805 2,769,962 Net loss per share, basic and diluted $ ( 0.60 ) $ ( 2.11 ) The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their inclusion would be anti-dilutive. As of March 31, 2022 2021 Series A convertible preferred stock — 54,143,753 Series B convertible preferred stock — 35,764,462 Common stock options and restricted stock units 8,525,522 1,717,446 Unvested common stock 200,341 849,884 Total 8,725,863 92,475,545
Segments	Segments The Company has determined that it operates and manages one operating segment, which is the business of researching and developing vaccines against infectious diseases. The Company’s chief operating decision maker, its chief executive officer, reviews financial information on an aggregate basis for the purpose of allocating resources. All assets of the Company are located in the United States.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Adopted Accounting Standards In December 2019, the FASB issued ASU 2019-12, Income Taxes—Simplifying the Accounting for Income Taxes (“ASU 2019-12”). The new guidance simplifies the accounting for income taxes by removing several exceptions in the current standard and adding guidance to reduce complexity in certain areas, such as requiring that an entity reflect the effect of an enacted change in tax laws or rates in the annual effective tax rate computation in the interim period that includes the enactment date. The new standard is effective for fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022 for all non-public entities, with early adoption permitted, and is effective for fiscal years beginning after December 15, 2020, including interim periods within those annual periods for public entities. Early adoption is permitted. The Company adopted ASU 2019-12 on January 1, 2021 and the standard did not have a material impact on its condensed financial statements and related disclosures. Recently Issued Accounting Standards There were no recently issued accounting standards that the Company believes have had or will have a material impact on its financial position or results of operations.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Computation of Basic and Diluted Net Loss Per Share	The following tables summarize the computation of the basic and diluted net loss per share (in thousands, except share and per share data): Three Months Ended 2022 2021 Numerator: Net loss $ ( 23,533 ) $ ( 5,851 ) Denominator: Weighted-average common shares outstanding, basic and 39,602,146 3,674,126 Less: Weighted average unvested common stock ( 200,341 ) ( 904,164 ) Weighted average shares used to compute net loss per 39,401,805 2,769,962 Net loss per share, basic and diluted $ ( 0.60 ) $ ( 2.11 )
Summary of Outstanding Potentially Dilutive Securities Excluded in Calculation of Diluted Net Loss Per Share	The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their inclusion would be anti-dilutive. As of March 31, 2022 2021 Series A convertible preferred stock — 54,143,753 Series B convertible preferred stock — 35,764,462 Common stock options and restricted stock units 8,525,522 1,717,446 Unvested common stock 200,341 849,884 Total 8,725,863 92,475,545

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Schedule of Fair Value Liabilities Measured on Recurring Basis
Schedule of Significant Unobservable Inputs Used in the Fair Value Measurements for the Derivative Liability	The following table summarizes information about the significant unobservable inputs used in the fair value measurements for the derivative liability: March 19, 2021 Probability of financing 100 % Probability of dissolution — Time to liquidity (years) — Discount rate 7.6 %
Schedule of Reconciliation of the Fair Value of the Derivative Liability Using Level 3 Significant Unobservable Inputs	The following table provides a reconciliation of the fair value of the derivative liability using Level 3 significant unobservable inputs (in thousands): Derivative Liability Fair value at December 31, 2020 $ ( 1,604 ) Change in fair value of embedded derivative liability ( 205 ) Reclassification of derivative liability into convertible preferred stock resulting from conversion of convertible promissory note 1,809 Fair value at March 31, 2021 $ —

Additional Balance Sheet Info_2

Additional Balance Sheet Information (Tables)	3 Months Ended
	Mar. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Schedule of Accrued and Other Current Liabilities	Accrued and other current liabilities consist of the following (in thousands): As of March 31, 2022 As of December 31, 2021 Taxes payable $ 35 $ — Accrued paid time off 480 342 Accrued bonus 729 2,216 Other accrued liabilities 5,759 1,977 Accrued 401k 213 156 ESPP liability 232 66 Total accrued and other current liabilities $ 7,448 $ 4,757

Convertible Promissory Note (Ta

Convertible Promissory Note (Tables)	3 Months Ended
	Mar. 31, 2022
Convertible Promissory Note [Abstract]
Summary Of Interest Expense Of Convertible Promissory Note	Interest expense incurred in connection with the Convertible Promissory Note consisted of the following (in thousands): Three Months Ended March 31, 2021 Coupon interest at 6% $ 86 Accretion of discount and amortization of issuance costs 177 Total interest expense on Convertible Promissory Note $ 263

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2022
Leases [Abstract]
Classified of ROU assets and lease liabilities and weighted average remaining lease term	Classification of ROU assets and lease liabilities and the weighted-average remaining lease term and discount rate associated with operating leases are as follows ($ in thousands): As of March 31, 2022 As of December 31, 2021 ROU assets: ROU assets - operating leases $ 3,309 $ — Lease liabilities: Current portion of operating lease liabilities 530 — Noncurrent portion of operating lease liabilities 2,964 — Total lease liabilities $ 3,494 $ — Weighted-average remaining lease term (in years): Operating leases 5.8 — Weighted-average discount rate: Operating leases 8.0 % —
Schedule of Component of Lease Cost	The components of lease costs are as follows (in thousands): Three Months Ended 2022 2021 Operating lease costs $ 185 $ — Short-term lease costs 141 14 Total lease costs $ 326 $ 14
Schedule of Maturities of Lease Liabilities	The maturities of lease liabilities and reconciliation to the present value of lease liabilities are as follows (in thousands): As of March 31, 2022 2022 $ — 2023 2,137 2024 2,201 2025 2,267 2026 2,335 Thereafter 2,405 Total undiscounted lease payments 11,345 Less: lease incentives ( 5,301 ) Less: imputed interest ( 2,550 ) Total lease liabilities 3,494 Less: current lease liabilities ( 530 ) Lease liabilities, net of current portion $ 2,964

Convertible Preferred Stock a_2

Convertible Preferred Stock and Stockholders' Equity (Deficit) (Tables)	3 Months Ended
	Mar. 31, 2022
Stockholders' Equity Note [Abstract]
Schedule of Convertible Preferred Stock	Convertible preferred stock authorized and issued and its principal terms as of March 31, 2021 consisted of the following ($ amounts in thousands): Shares Shares Issued Shares of Aggregate Carrying Series A-1 49,193,959 49,193,959 11,837,711 $ 47,300 $ 46,917 Series A-2 4,949,794 4,949,794 1,191,082 $ 3,807 $ 4,150 Series B-1 32,958,612 32,958,612 7,930,924 $ 93,000 $ 92,654 Series B-2 2,805,850 2,805,850 675,181 $ 6,730 $ 7,917 Total 89,908,215 89,908,215 21,634,898 $ 150,837 $ 151,638
Schedule of common stock reserved for future issuance	Common stock reserved for future issuance consisted of the following: As of March 31, 2022 Common stock options and restricted stock units granted and outstanding 8,525,522 Shares available for issuance under the equity incentive plans 3,771,600 Shares available for issuance under the 2021 Employee Stock Purchase Plan 777,685 Total common stock reserved for issuance 13,074,807
Summary of the Status of the Options Issued Under the Plan	A summary of the status of the options issued under the Company’s equity incentive plans as of March 31, 2022, and information with respect to the changes in options outstanding is as follows : Options Weighted Average Exercise Weighted Average Remaining Aggregate Balance at December 31, 2021 6,591,727 $ 8.04 9.26 Authorized increase in plan shares — — — — Granted 1,258,140 17.48 — — Exercised (including early) ( 295,764 ) 0.94 — $ 4,290,213 Balance at March 31, 2022 7,554,103 $ 9.89 9.19 $ 11,365,470 Vested and expected to vest as of 7,554,103 $ 9.89 9.19 $ 11,365,470 Vested and exercisable at 1,563,412 $ 5.99 9.00 $ 3,058,199
Summary of the RSU under Equity incentive plan	A summary of the status of RSUs issued under the Company’s equity incentive plans as of March 31, 2022, and information with respect to the changes in RSUs outstanding is as follows: Service-based RSUs Performance-based RSUs Units Weighted Average Grant-Date Fair Value Units Weighted Average Grant-Date Fair Value Nonvested at December 31, 2021 388,500 $ 25.96 — $ — Granted 522,919 $ 17.60 60,000 $ 18.74 Nonvested at March 31, 2022 911,419 $ 21.16 60,000 $ 18.74 Expected to vest at March 31, 2022 911,419 $ 21.16 — $ —
Schedule of Stock-based Compensation Expense for All Equity Awards	Stock-based compensation expense for all equity awards and the ESPP has been reported in the condensed statements of operations and comprehensive loss as follows (in thousands): Three Months Ended 2022 2021 Research and development $ 1,687 $ 113 General and administrative 2,863 163 Total $ 4,550 $ 276
Summary of Assumptions Used in Black-Scholes Model	The fair value of each stock option granted was determined using the Black-Scholes option pricing model. The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee and nonemployee stock option grants issued during years ended were as follows: Three Months Ended 2022 2021 Risk-free rate of interest 1.43 %- 2.12 % 0.53 %- 0.64 % Expected term (years) 5.77 - 6.08 years 5.48 - 6.12 years Expected stock price volatility 89.3 % - 118.1 % 86.0 % - 87.9 % Dividend yield 0 % 0 %

Description of Business - Addit

Description of Business - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Aug. 02, 2021	Aug. 31, 2021	Jul. 31, 2021	Mar. 31, 2021	Mar. 31, 2022	Dec. 31, 2021
Subsidiary, Sale of Stock [Line Items]
Accumulated Deficit					$ 117,602	$ 94,069
Cash					261,357	$ 279,082
Restricted Cash					$ 1,100
Stock split			1-for-4.1557	1-for-4.1557
Sale of common stock					39,724,867	39,429,103
IPO [Member]
Subsidiary, Sale of Stock [Line Items]
Proceeds from Issuance Initial Public Offering	$ 190,700
Sale of common stock	12,133,333
Offering price per share	$ 15
Additional shares purchasable by underwriters	1,819,999
Preferred stock, shares outstanding	89,908,215
Common stock converted	21,634,898	21,634,898

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022USD ($)Segmentshares	Dec. 31, 2021USD ($)shares
Number of shares subject to repurchase | shares	200,341	253,824
Liabilities with shares issued with repurchase rights | $	$ 0.1	$ 0.2
Number Of Reporting Units | Segment	1

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Numerator:
Net loss	$ (23,533)	$ (5,851)
Denominator:
Weighted-average common shares outstanding, basic and diluted	39,602,146	3,674,126
Less: Weighted average unvested common stock	(200,341)	(904,164)
Weighted average shares used to compute net loss per share, basic and diluted	39,401,805	2,769,962
Net loss per share, basic and diluted	$ (0.60)	$ (2.11)

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Summary of Outstanding Potentially Dilutive Securities Excluded in Calculation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive common equivalent shares	8,725,863	92,475,545
Common Stock [Member] | Stock Option [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive common equivalent shares	8,525,522	1,717,446
Unvested Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive common equivalent shares	200,341	849,884
Series A
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive common equivalent shares	0	54,143,753
Series B
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive common equivalent shares	0	35,764,462

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Mar. 19, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 0		$ 0
Convertible preferred stock, Shares issued upon conversion		21,634,898
Loss on extinguishment of convertible promissory note	$ 0	$ (754)
Series B-2 Convertible Preferred Stock [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Convertible preferred stock, Shares issued upon conversion				2,805,850
Operating Expense [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Increase in the fair value of the derivative liability		200
Operating Expense [Member] | Series B-2 Convertible Preferred Stock [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Loss on extinguishment of convertible promissory note		$ 800

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Significant Unobservable Inputs Used in the Fair Value Measurements for the Derivative Liability (Details)	Mar. 19, 2021
Probability of financing
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liability	100
Probability of dissolution
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liability	0
Time to liquidity (years)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liability	0
Discount rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liability	7.6

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Reconciliation of the Fair Value of the Derivative Liability Using Level 3 Significant Unobservable Inputs (Details) - Level 3 $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning balance	$ (1,604)
Change in fair value of embedded derivative liability	(205)
Reclassification of derivative liability into convertible stock resulting from conversion of convertible promissory note	1,809
Ending balance	$ 0

Grant Agreement - Additional In

Grant Agreement - Additional Information (Details) - BMGF Grant - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Grant Agreement [Line Items]
Grant received	$ 10,000		$ 10,000
Deferred revenue	0		$ 600
Revenue since inception	10,000
Funding received	0	$ 2,700
Revenue from grant	$ 600	$ 2,000

Additional Balance Sheet Info_3

Additional Balance Sheet Information - Schedule of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Taxes payable	$ 35
Accrued paid time off	480	342
Accrued bonus	729	2,216
Other accrued liabilities	5,759	1,977
Accrued 401K	213	156
ESPP Liability	232	66
Accrued Liabilities, Current, Total	$ 7,448	$ 4,757

License Agreements - Additional

License Agreements - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Aug. 01, 2018
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, shares issued	39,724,867		39,429,103
NIH Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment of license fee	$ 100,000
Potential milestone payments	8,600
NIH Agreement | Research and Development Expense [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Payment of license fee	0	$ 0
U W Two Thousand And Eighteen Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock, shares issued				192,276
Potential Payments for Future Development Regulatory and Sales Based Milestones	1,350
Total Milestone Payments	8,100
Uw Flu License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Aggregate Payments Related To Cumulative Net Sales Thresholds	$ 6,400
License Agreement Expiry Year	2041
U T Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone payments	$ 4,600

Convertible Promissory Note - A

Convertible Promissory Note - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 19, 2021	Aug. 31, 2020	Mar. 31, 2022	Mar. 31, 2021
Debt Conversion [Line Items]
Convertible promissory note issued		$ 6,500
Accrued interest rate, per annum		6.00%
Promissory note maturity period		2 years	2 years
Derivative Liability, Fair Value, Gross Liability			$ 1,800
Debt discount interest rate, effective percentage			23.80%
Loss on extinguishment of convertible promissory note			$ 0	$ (754)
Convertible Promissory Note
Debt Conversion [Line Items]
Debt Conversion, Converted Instrument, Amount		$ 140,000
Series A3 Convertible Preferred Stock | Convertible Promissory Note
Debt Conversion [Line Items]
Share price, percentage		85.00%
Series B-2 Convertible Preferred Stock [Member]
Debt Conversion [Line Items]
Promissory note and derivative liability conversion into share	2,805,850
Shares issued price per share	$ 2.39846
Minimum [Member] | Series A3 Convertible Preferred Stock | Convertible Promissory Note
Debt Conversion [Line Items]
Proceeds from Convertible Debt		$ 5,000

Convertible Promissory Note - S

Convertible Promissory Note - Summary of Interest Expense of Convertible Promissory Note (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022USD ($)
Convertible Promissory Note [Abstract]
Coupon Interest at 6%	$ 86
Accretion of discount and amortization of issuance costs	(177)
Total interest expense on Convertible Promissory Note	$ 263

Convertible Preferred Stock a_3

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 02, 2021	Mar. 19, 2021	Aug. 31, 2021	Jul. 31, 2021	Feb. 28, 2021	Aug. 31, 2020	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Class Of Stock [Line Items]
Common stock, shares authorized	500,000,000						500,000,000		500,000,000
Common stock, par value							$ 0.0001		$ 0.0001
Convertible promissory note						$ 6,500
Gross Proceeds from issuance of convertible preferred stock, net of issuance costs								$ 113,659
Accumulated deficit							(117,602)		$ (94,069)
Convertible promissory note issued						6,500
Allocated Share Based Compensation Expense							$ 4,550	276
Common stock, shares issued							39,724,867		39,429,103
Common Stock Shares Outstanding							39,524,526		39,175,279
Granted							1,258,140
Compensation expense recognition vesting period							3 years 4 months 17 days
Common Stock, Capital Shares Reserved for Future Issuance							13,074,807
Preferred stock, shares authorized	50,000,000
Non-cash, stock-based compensation expense							$ 4,550	$ 276
Reverse stock split				1-for-4.1557				1-for-4.1557
2021 Stock Incentive Plan
Class Of Stock [Line Items]
Percentage Increase In Common Stock Shares Reserved For Future Issuance							5.00%
Increase In Common Stock Shares Reserved For Future Issuance							1,971,455
Common stock, shares issued							50,000,000
Stock option granted vesting period							4 years
Stock option granted maximum term							10 years
Percentage of exercise price to fair market value common stock on grant date							100.00%
Common Stock, Capital Shares Reserved for Future Issuance							4,600,000
Restricted Stock
Class Of Stock [Line Items]
Unrecognised compensation cost							$ 17,300
Stock Options [Member]
Class Of Stock [Line Items]
Cash received for early exercise of unvested options							$ 100
Weighted-average grant date fair value							$ 13.08
Granted							1,258,140
Compensation expense recognition vesting period							4 years
Unrecognised compensation cost							$ 52,300
Stock Options [Member] | 2021 Stock Incentive Plan
Class Of Stock [Line Items]
Percentage of exercise price to fair market value common stock on grant date							110.00%
IPO [Member]
Class Of Stock [Line Items]
Proceeds from initial public offering, net of offering costs	$ 190,700
Common stock, shares issued	12,133,333
Conversion of Stock, Shares Converted	21,634,898		21,634,898
Preferred Stock, Shares Outstanding	89,908,215
2021 Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Percentage Increase In Common Stock Shares Reserved For Future Issuance							1.00%
Increase In Common Stock Shares Reserved For Future Issuance							394,291
Allocated Share Based Compensation Expense							$ 100	$ 0
Common stock, shares issued							15,000,000
Common Stock, Capital Shares Reserved for Future Issuance							400,000
Percentage Of Common Stock Outstanding							1.00%
Number of purchased shares by the employee							16,606
Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Number of convertible preferred stock sold during the period								21,944,874
Series A1 Convertible Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, shares issued					21,944,874
Series B Preferred Stock [Member]
Class Of Stock [Line Items]
Gross Proceeds from issuance of convertible preferred stock, net of issuance costs								$ 92,700
Preferred stock, shares issued								35,764,462
Preferred stock, par value								$ 0.0001
Series B1 Convertible Preferred Stock
Class Of Stock [Line Items]
Proceeds from issuance of convertible preferred stock								$ 350
Convertible preferred stock price per share								$ 2.82172
Preferred stock, shares issued								32,958,612
Series B-2 Convertible Preferred Stock [Member]
Class Of Stock [Line Items]
Offering's share price		85.00%
Accrued interest						$ 200
Convertible conversation preferred shares		2,805,850
Preferred stock, shares issued								2,805,850

Leases - Additional Information

Leases - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2020
Lessee, Lease, Description [Line Items]
Lease agreement option to extend	The lease agreement is twelve months and provides for renewal options.
Monthly Base Rent	$ 16,000
Lease liability	3,494,000		$ 0
Right-of-use assets - operating leases	$ 3,309,000		$ 0
Lease Agreements [Member]
Lessee, Lease, Description [Line Items]
Lease agreement option to extend		The lease agreement expires in December 2027 and provides for a one-time option to extend for a period of five additional years.
Monthly Base Rent		$ 200,000
Allowance for tenant improvements		$ 5,300,000
Lease term option to extend for additional years		5 years
Monthly base rent yearly increase percentage		3.00%
Standby Letters of Credit | Lease Agreements [Member]
Lessee, Lease, Description [Line Items]
Standby letters of credit		$ 1,100,000
Second Anniversary [Member] | Lease Agreements [Member]
Lessee, Lease, Description [Line Items]
Standby letters of credit		700,000
First Anniversary [Member] | Lease Agreements [Member]
Lessee, Lease, Description [Line Items]
Standby letters of credit		$ 900,000

Leases - Classified of ROU asse

Leases - Classified of ROU assets and lease liabilities and weighted average remaining lease term (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Right-of-use assets - operating leases	$ 3,309		$ 0
Current portion of operating lease liabilities	530
Noncurrent portion of operating lease liabilities	2,964
Total lease liabilities	$ 3,494		$ 0
Weighted-average remaining lease term (in years): Operating leases	5 years 9 months 18 days
Weighted-average discount rate: Operating leases	8.00%

Leases - Schedule of Component

Leases - Schedule of Component of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Leases [Abstract]
Operating lease costs	$ 185
Short-term Lease, Cost	141	14
Total lease costs	$ 326	$ 14

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2020
Leases [Abstract]
2022	$ 0
2023	2,137
2024	2,201
2025	2,267
2026	2,335
Thereafter	2,405
Lessee, Operating Lease, Liability, Undiscounted Excess Amount, Total	11,345
Less: lease incentives	(5,301)
Less: imputed interest	(2,550)
Total lease liabilities	3,494		$ 0
Less: current lease liabilities	530
Operating lease liabilities, net of current portion	$ 2,964

Convertible Preferred Stock a_4

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Schedule of Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Mar. 31, 2021
Class Of Stock [Line Items]
Share Authorized and Outstanding	89,908,215
Shares Issued and Outstanding		89,908,215
Convertible preferred stock, Shares issued upon conversion		21,634,898
Aggregate Liquidation Preference		$ 150,837
Carry Value		$ 151,638
Series A-1
Class Of Stock [Line Items]
Share Authorized and Outstanding		49,193,959
Shares Issued and Outstanding		49,193,959
Convertible preferred stock, Shares issued upon conversion		11,837,711
Aggregate Liquidation Preference		$ 47,300
Carry Value		$ 46,917
Series A-2
Class Of Stock [Line Items]
Share Authorized and Outstanding		4,949,794
Shares Issued and Outstanding		4,949,794
Convertible preferred stock, Shares issued upon conversion		1,191,082
Aggregate Liquidation Preference		$ 3,807
Carry Value		$ 4,150
Series B-1
Class Of Stock [Line Items]
Share Authorized and Outstanding		32,958,612
Shares Issued and Outstanding		32,958,612
Convertible preferred stock, Shares issued upon conversion	7,930,924
Aggregate Liquidation Preference		$ 93,000
Carry Value	$ 92,654
Series B-2
Class Of Stock [Line Items]
Share Authorized and Outstanding	2,805,850
Shares Issued and Outstanding		2,805,850
Convertible preferred stock, Shares issued upon conversion		675,181
Aggregate Liquidation Preference		$ 6,730
Carry Value		$ 7,917

Convertible Preferred Stock a_5

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Schedule of Common Stock Reserved for Future Issuance (Details)	Mar. 31, 2022shares
Class Of Stock [Line Items]
Convertible preferred stock	13,074,807
Equity Incentive Plan [Member]
Class Of Stock [Line Items]
Convertible preferred stock	3,771,600
2021 Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Convertible preferred stock	777,685
Common Stock Options and Restricted Stock Units [Member]
Class Of Stock [Line Items]
Convertible preferred stock	8,525,522

Convertible Preferred Stock a_6

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Summary of the Status of the Options Issued Under the Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Stockholders' Equity Note [Abstract]
Options Outstanding, Balance at December 31, 2021	6,591,727
Authorized increase in plan shares	0
Options Outstanding, Granted	1,258,140
Options Outstanding, Exercised (including early)	(295,764)
Options Outstanding, Balance at March 31, 2022	7,554,103	6,591,727
Options Outstanding, Vested and expected to vest as of March 31, 2022	7,554,103
Options Outstanding, Vested and exercisable at March 31, 2022	1,563,412
Weighted average exercise price per share, Balance at December 31, 2021	$ 8.04
Weighted average exercise price per share, Granted	17.48
Weighted average exercise price per share, Exercised (including early)	0.94
Weighted average exercise price per share, Balance at March 31, 2022	9.89	$ 8.04
Weighted average exercise price per share, Vested and expected to vest as of March 31, 2022	9.89
Weighted average exercise price per share, Vested and exercisable at March 31, 2022	$ 5.99
Weighted average remaining contractual term (Years)	9 years 2 months 8 days	9 years 3 months 3 days
Weighted average remaining contractual term, Vested and expected to vest as of March 31, 2022	9 years 2 months 8 days
Weighted average remaining contractual term, Vested and exercisable at March 31, 2022	9 years
Aggregate intrinsic value, Exercised (including early)	$ 4,290,213
Aggregate intrinsic value, Balance at March 31, 2022	11,365,470
Vested and expected to vest as of March 31, 2022	11,365,470
Aggregate intrinsic value, Vested and exercisable at March 31, 2022	$ 3,058,199

Convertible Preferred Stock a_7

Convertible Preferred Stock and Stockholders Equity (Deficit) - Summary of RSU Equity incentive plans (Details) - $ / shares	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	1,258,140
Expected to vest at March 31, 2022	7,554,103
Weighted average exercise price per share, Vested and exercisable at March 31, 2022	$ 5.99
Service Based RSU Member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested at December 31, 2021	911,419	388,500
Granted	522,919
Nonvested at March 31, 2022	911,419	388,500
Expected to vest at March 31, 2022	911,419
Weighted Average Nonvested at December 31, 2021	$ 21.16	$ 25.96
Weight granted fair value Nonvested Granted	17.60
Weighted Average Grant Nonvested at March 31, 2022	21.16	$ 25.96
Weighted average exercise price per share, Vested and exercisable at March 31, 2022	$ 21.16
Performance Based RSUs Member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested at December 31, 2021	60,000
Granted	60,000
Nonvested at March 31, 2022	60,000
Weighted Average Nonvested at December 31, 2021	$ 18.74
Weight granted fair value Nonvested Granted	18.74
Weighted Average Grant Nonvested at March 31, 2022	$ 18.74

Convertible Preferred Stock a_8

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Schedule of Stock-based Compensation Expense for All Equity Awards (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Class Of Stock [Line Items]
Research and development	$ 4,550	$ 276
Research and Development Expense [Member]
Class Of Stock [Line Items]
Research and development	1,687	113
General and Administrative [Member]
Class Of Stock [Line Items]
Research and development	$ 2,863	$ 163

Convertible Preferred Stock a_9

Convertible Preferred Stock and Stockholders' Equity (Deficit) - Summary of Assumptions Used in Black-Scholes Model (Details)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Class Of Stock [Line Items]
Risk-free rate of interest, Minimum	1.43%	0.53%
Risk-free rate of interest, Mximum	2.12%	0.64%
Expected stock price volatility, Minimum	89.30%	86.00%
Expected stock price volatility, Maximum	118.10%	87.90%
Dividend yield	0.00%	0.00%
Minimum [Member]
Class Of Stock [Line Items]
Expected term (years)	5 years 9 months 7 days	5 years 5 months 23 days
Maximum [Member]
Class Of Stock [Line Items]
Expected term (years)	6 years 29 days	6 years 1 month 13 days

Income Taxes (Additional Inform

Income Taxes (Additional Information) (Details)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Effective Income Tax Rate	0.00%	0.00%
Difference Between Effective Tax Rate	0.00%	0.00%
Federal Statutory Rate	21.00%	21.00%

Employee Savings Plan - Additio

Employee Savings Plan - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Defined Contribution Plan Disclosure [Line Items]
Employer discretionary contribution amount
Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Percent of employees gross pay	90.00%