Vaxart Inc美股招股说明书(2026-05-04版)

We have entered into an At the Market Offering Agreement, dated March 21, 2025 (the “Sales Agreement”) with Citizens JMPSecurities, LLC and B. Riley Securities, Inc. (the “Sales Agents”) relating to shares of our common stock, par value $0.0001 pershare, offered by this prospectus supplement and the accompanying prospectus. In accordance with the terms of the SalesAgreement, we may offer and sell shares of our common stock having an aggregate offering price of up to $49,772,479 from timeto time through the Sales Agents. Upon our delivery of a placement notice and subject to the terms and conditions of the Sales Agreement, the Sales Agents may sellthe common stock by methods deemed to be an “at the market” offering as defined in Rule 415 promulgated under the SecuritiesAct of 1933, as amended (the “Securities Act”), including sales made directly on The Nasdaq Capital Market (“Nasdaq”), on anyother existing trading market for the common stock or to or through a market maker other than on an exchange. In addition, withour prior written approval, the Sales Agents may also sell the common stock by any other method permitted by law, including inprivately negotiated transactions. If we and the Sales Agents agree on any method of distribution other than sales of shares of ourcommon stock on or through The Nasdaq Capital Market or another existing trading market in the United States at market prices,we will file a further prospectus supplement providing all information about such offering as required by Rule 424(b) under theSecurities Act. The Sales Agents are not required to sell any specific number or dollar amount of our common stock, but will useits commercially reasonable efforts, as our sales agent and subject to the terms of the sales agreement, to sell the shares of commonstock offered, as instructed by us and applicable state and federal laws, rules and regulations and the rules of the Nasdaq. There isno arrangement for funds to be received in any escrow, trust or similar arrangement. Each of the Sales Agents will be entitled to compensation under the terms of the sales agreement at a fixed commission rate, in theaggregate, of up to 3% of the gross sales price per share sold, in addition to reimbursement of certain expenses. See “Plan ofDistribution” for information relating to certain expenses of the sales agent to be reimbursed by us. In connection with the sale of common stock on our behalf, each of the Sales Agents may be deemed to be an “underwriter” withinthe meaning of the Securities Act and the compensation to each of the Sales Agents will be deemed to be underwritingcommissions or discounts. We have also agreed to provide indemnification and contribution to each of the Sales Agents withrespect to certain liabilities, including liabilities under the Securities Act. The net proceeds we receive from any sales under this prospectus supplement will be the gross proceeds from such sales less thecommissions and any other costs we may incur in offering the common stock. See “Use of Proceeds” and “Plan of Distribution”for additional information. Our common stock is traded on the OTCQX® Best Market under the symbol “VXRT.” On April 10, 2026, the reported closingprice of the common stock was $0.63 per share. Investing in our securities involves risk. See“Risk Factors”beginning on pageS-4of this prospectus supplement, on page2of the accompanying base prospectus and in our filings with the Securities Exchange Commission (the“SEC”), that areincorporated by reference herein and therein to read about factors you should consider before investing in our securities. Neither the SEC nor any state securities commission has approved or disapproved of these securities or determined if thisprospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is acriminal offense. CitizensCapital MarketsB. Riley Securities The date of this prospectus supplement is April 30, 2026. Table of Contents TABLE OF CONTENTS ABOUT THIS PROSPECTUS SUPPLEMENTPROSPECTUS SUPPLEMENT SUMMARYTHE OFFERINGRISK FACTORSSPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTSUSE OF PROCEEDSDIVIDEND POLICYDILUTIONPLAN OF DISTRIBUTIONLEGAL MATTERSEXPERTSWHERE YOU CAN FIND ADDITIONAL INFORMATIONINCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE ABOUT THIS PROSPECTUS SUPPLEMENT We provide information to you about this offering of securities in two separate documents that are bound together: (1) thisprospectus supplement, which describes the specific details regarding this offering; and (2) the accompanying base prospectus,which provides general information, some of which may not apply to this offering. If information in this prospectus supplement isinconsistent with the accompanying base prospectus, you should rely on this prospectus supplement. However, if any statement inone of these documents is inconsistent with a statement in another document having a later date - for example, a documentincorporat