Vaxart Inc美股招股说明书(2025-11-05版)

(To Prospectus Dated May 5, 2023) This prospectus supplement and the accompanying prospectus relate to the offer and sale of 11,111,111 shares of our commonstock, par value $0.0001 per share. The offering price for each share of common stock is $0.45. Our common stock is quoted on the OTCQX® Best Market under the symbol “VXRT.” On November 3, 2025, the last reportedsale price of our common stock on the OTCQX was $0.33 per share. Investing in our common stock involves risk. See“Risk Factors”beginning on page S-5 of this prospectus supplement, andin our filings with the Securities Exchange Commission (“SEC”) that are incorporated by reference into this prospectussupplement before making your investment decision. 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. Delivery of the shares of common stock is expected to be made on or about November 6, 2025. The date of this prospectus supplement is November 4, 2025 Table of Contents PROSPECTUS SUPPLEMENT 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 PROSPECTUS ABOUT THIS PROSPECTUS SUPPLEMENT We provide information to you about this offering of shares of our common stock in two separate documents that are boundtogether: (1) this prospectus supplement, which describes the specific details regarding this offering; and (2) the accompanyingbase prospectus, which provides general information, some of which may not apply to this offering. If information in thisprospectus supplement is inconsistent with the accompanying base prospectus, you should rely on this prospectus supplement.However, if any statement in one of these documents is inconsistent with a statement in another document having a later date —for example, a document incorporated by reference in this prospectus supplement — the statement in the document having the laterdate modifies or supersedes the earlier statement as our business, financial condition, results of operations, and prospects may havechanged since the earlier dates. We have not authorized anyone to provide you with any information that is in addition to or different from that contained orincorporated by reference in this prospectus supplement, the accompanying base prospectus, or in any free writing prospectus wehave prepared. We take no responsibility for, and provide no assurance as to the reliability of, any other information that othersmay give you. We are not making an offer to sell or soliciting an offer to buy our securities in any jurisdiction where an offer orsolicitation is not authorized or in which the person making that offer or solicitation is not qualified to do so or to anyone to whomit is unlawful to make an offer or solicitation. You should assume that the information appearing in this prospectus supplement, theaccompanying base prospectus, the documents incorporated by reference herein and therein, and in any free writing prospectus thatwe may authorize for use in connection with this transaction, is accurate only as of the date of those respective documents. Ourbusiness, financial condition, results of operations, and prospects may have changed since those dates. You should read thisprospectus supplement, the accompanying base prospectus, the documents incorporated by reference into this prospectussupplement, and any free writing prospectus that we may authorize for use in connection with this transaction in their entiretybefore making an investment decision. You should also read and consider the information in the documents to which we havereferred you in the section of this prospectus supplement titled “Where You Can Find Additional Information.” We are offering to sell shares of common stock only in jurisdictions where offers and sales are permitted. The distribution of thisprospectus supplement and the accompanying base prospectus and the offering of the common stock in certain jurisdictions maybe restricted by law. This prospectus supplement and the accompanying base prospectus do not constitute, and may not be used inconnection with, an offer to sell, or a solicitation of an offer to buy, any securities offered by this prospectus supplement and theaccompanying base prospectus by any person in any jurisdiction in which it is unlawful for such person to make such an offer orsolicitation. When we refer to “Vaxart,” “we,” “our,” “us,” and the “Company” in this prospectus supplement, we mean Vaxart, Inc., and ourconsolidated subsidiaries unless otherwise specified. Vaxart® and the Vaxart logo are some of our trademarks used in this prospectus supplement. T