Vaxart, Inc.

You should consider the risks and uncertainties described under Item 1A of Part I of our Annual Report on Form 10-K for the fiscal year ended December 31, 2025, which we filed with the Securities and Exchange Commission on March 13, 2026, together with all other information contained or incorporated by reference in this Quarterly Report on Form 10-Q, when evaluating our business and our prospects. Except as set forth below, there have been no material changes from the risk factors set forth in Part I, Item 1A of our Annual Report on Form 10-K for the year ended December 31, 2025. The risk factors below update certain risk factors included in the Annual Report and, for convenience, restate certain others in their entirety.

We have identified conditions that raise substantial doubt about our ability to continue as a going concern, and we will require substantial additional funding to finance our operations.

We have incurred significant losses and negative cash flows from operations since our inception. As of September 30, 2026, we had $65.5 million of cash, cash equivalents and short-term investments and an accumulated deficit of $486.2 million. In our Annual Report on Form 10-K for the year ended December 31, 2025, we reported that the conditions that had previously raised substantial doubt about our ability to continue as a going concern had been alleviated. In the second quarter of 2026, management concluded that our cash, cash equivalents and investments are not sufficient to fund our planned operations for at least twelve months from the date of issuance of our financial statements, and these conditions raise substantial doubt about our ability to continue as a going concern. Based on management’s current plan, we expect our existing cash resources to fund our operations into the second quarter of 2027. Management’s plans include raising additional capital through the sale of equity securities, including under the March 2025 ATM and the April 2026 ELOC to the extent available to us, obtaining funding under the 2024 ATI-RRPV Contract and receiving payments under the License and Collaboration Agreement, and, if we are unable to raise additional capital in sufficient amounts or on acceptable terms, further reducing or delaying operating expenses. There can be no assurance that we will be successful in raising additional capital on acceptable terms or at all.

Our ability to sell equity securities is constrained because our common stock is quoted on the OTCQX rather than listed on a national securities exchange and is subject to state securities law requirements, as described below, and the amount available under the 2024 ATI-RRPV Contract has been reduced and remains subject to the government’s funding decisions. If we are unable to obtain sufficient funding, we could be forced to delay, reduce the scope of or eliminate certain of our development programs, explore other strategic alternatives or cease operations, and we may be forced to liquidate our assets, in which case the values we receive for our assets in liquidation or dissolution could be significantly lower than the values reflected in our unaudited condensed consolidated financial statements. Our unaudited condensed consolidated financial statements have been prepared assuming that we will continue as a going concern and do not include any adjustments that might result from the outcome of this uncertainty.

Currently, a significant portion of the funds to study our COVID vaccine candidate is expected to come from HHS BARDA. If HHS BARDA were to further reduce, eliminate, delay, or object to funding available to us under the 2024 ATI-RRPV Contract, this could have a significant, negative impact on our revenues and cash flows, and we may be forced to suspend or terminate the continued development of the product candidate or obtain alternative sources of funding.

In June 2024, we entered into the 2024 ATI-RRPV Contract with ATI, the Rapid Response Partnership Vehicle’s Consortium Management Firm funded by HHS BARDA. Pursuant to Modification No. 7 to the 2024 ATI-RRPV Contract, dated June 22, 2026, the total amount of authorized funding under the 2024 ATI-RRPV Contract was reduced from $460.7 million to $344.8 million (a decrease of $115.9 million). The June 22, 2026 Modification No. 7 reduction to total authorized funding under the 2024 ATI-RRPV Contract follows the reduction in scope of work that resulted from previously issued stop work orders that halted enrollment and therefore reduced the size of the study.

We anticipate that a significant portion of the funding to further develop our COVID-19 vaccine candidate will come from the remaining amounts to be received under the 2024 ATI-RRPV Contract. The 2024 ATI-RRPV Contract provides that the government has the right to determine whether to fund the continued performance of the study after the initial funding. In the second half of 2024, the Company initiated and completed enrollment of the 400-participant sentinel cohort of its Phase 2b study comparing the Company’s XBB COVID-19 vaccine candidate to an approved mRNA XBB comparator. In January 2025, the independent data safety monitoring board (DSMB) reviewed 30-day sentinel cohort data and recommended the study proceed without modifications. On July 6, 2026, we announced topline 12-month data from the 400-participant sentinel cohort of the Phase 2b study, which was not powered to determine comparative efficacy between the two arms. Topline data from the complete study, comprising the sentinel cohort and the approximately 5,000 participants enrolled in the main cohort, are anticipated in the first half of 2027. See Part I, Item 2, “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Our Product Pipeline—Coronavirus Vaccine.”

In February 2025, ATI issued a stop work order on the 2024 ATI-RRPV Contract. Subsequently, in April 2025, the Company received written notification from ATI lifting the stop work order, permitting the Company to resume incurring costs, participating in meetings, and communicating with the Government and ATI concerning the project award. In May 2025, HHS BARDA approved initiation of dosing in the 10,000-participant main cohort of the Phase 2b study, and the Company announced the first participant dosed later that month. In August 2025, ATI issued a second stop work order directing the Company to halt further screening and enrollment for the COVID-19 Phase 2b trial under the 2024 ATI-RRPV Contract. As of the August notification date, the Company had enrolled approximately half of the targeted number of participants for the main cohort of the study. On October 8, 2025, ATI issued a Follow-Up Notice confirming BARDA’s intent to stop all ongoing enrollment under the contract while permitting continued follow-up and planned analyses of both the sentinel cohort and the enrolled main study population.

Even as we continue to receive funds under the 2024 ATI-RRPV Contract, the terms of the 2024 ATI-RRPV Contract may unfavorably change, or the amount of funding may further decrease. If there is any government decision to discontinue funding under the 2024 ATI-RRPV Contract, our revenues and cash flows would be significantly and negatively impacted and we may be forced to seek alternative sources of funding, which may not be available on non-dilutive terms, terms favorable to us, or at all.

There can be no assurance thatDynavax will continue to perform its obligations under the License and Collaboration Agreement or that Dynavax will not exercise its right to terminate the agreement.

On February 10, 2026, Sanofi completed its acquisition of Dynavax. As a result of the consummation of the merger, Dynavax became an indirect wholly owned subsidiary of Sanofi. Sanofi’s vaccine portfolio includes multiple influenza vaccines (Fluzone High-Dose, Flublok, Fluzone) and a co-commercialized protein-based COVID-19 vaccine, Nuvaxovid. Sanofi is also developing a combination, single-shot COVID-19/flu vaccine for adults 50+ using Novavax technology, targeting a non-mRNA approach. Sanofi can be expected to make its decisions regarding further investment for further investments in our Dynavax partnered COVID-19 vaccine candidate and potentially other Vaxart assets in the context of this larger vaccine portfolio.

Changes in the regulatory environment for vaccines could adversely impact our product development and commercialization efforts.

Recent developments in U.S. vaccine oversight, including increased involvement by the FDA Commissioner’s office in approval decisions and changes to the Advisory Committee on Immunization Practices (ACIP), may create additional uncertainty in the regulatory process. These changes could result in new or heightened requirements for clinical data, slower review timelines, or altered recommendations for use, any of which could adversely affect the timing, likelihood of approval, and market acceptance of our vaccine candidates.

Ourcommon stock has been delisted from The Nasdaq Capital Market. There can therefore be no assurance that it will trade on a national exchange again.

Effective July 8, 2025, Nasdaq suspended trading in our common stock, and on September 19, 2025, Nasdaq informed us that our common stock would be delisted from The Nasdaq Capital Market because of our continued failure to comply with the minimum bid price requirement under Nasdaq Listing Rule 5550(a)(2). Our common stock was delisted from The Nasdaq Capital Market effective December 1, 2025, and is quoted on the OTCQX Best Market (“OTCQX”) under the symbol “VXRT.” We can provide no assurance that our common stock will continue to be quoted on the OTCQX, that broker-dealers will continue to provide public quotations for our common stock or that the trading volume of our common stock will be sufficient to provide an efficient trading market. Securities quoted on the OTC markets generally have substantially less liquidity than securities listed on a national securities exchange, which reduces our ability to issue additional securities or obtain additional financing. In addition, because our common stock is no longer listed on a national securities exchange, it is not a “covered security” under the National Securities Markets Improvement Act of 1996, and offers and sales of our securities are subject to the securities (“blue sky”) laws of each state in which they are made. This state-level regulation imposes additional compliance requirements on us and on broker-dealers that trade in our securities, has limited our use of the March 2025 ATM and may further reduce the liquidity of our common stock and our ability to raise capital.

We may not be able to retain coverage by securities or industry analysts because our common stock is not traded on a national securities exchange.

The trading in our common stock is influenced by independent research and reports that securities or industry analysts publish about us or our business from time to time. Because our common stock trades on the OTCQX Best Market rather than a national securities exchange, our exposure to media and coverage by securities and industry analysts may be limited. Further, if one or more of the analysts who cover us should downgrade our shares or change their opinion of our business prospects, our share price may be adversely impacted.

Use of artificial intelligence in our operations could result in reputational or competitive harm and legal or regulatory liability.

We have incorporated, and may continue to incorporate, certain AI solutions into our operations, and the use of AI involves various risks and challenges that could adversely affect our business. The development and deployment of AI systems involve inherent technical complexities and uncertainties, and our AI systems may encounter unexpected technical difficulties, limitations or errors, including inaccuracies in data processing or flawed algorithms. In addition, our competitors or other third parties may incorporate AI into their operations and products more quickly or more successfully than us, which could impair our ability to compete effectively.

The use of AI applications, including large language models, may in the future result in cybersecurity incidents that implicate the personal data of end users of such applications. Any such cybersecurity incidents related to our use of AI applications could adversely affect our business and reputation. AI also presents emerging ethical issues, and if our use of AI becomes controversial, we may experience brand or reputational harm, competitive harm, regulatory scrutiny or legal liability. In addition, use of personal data in generative AI technologies is subject to various privacy laws and other privacy obligations. Governments have passed and are likely to pass additional laws regulating generative AI. The introduction of AI technologies into our operations may result in new or enhanced governmental or regulatory scrutiny, litigation, confidentiality or security risks or other complications that could adversely affect our business. The regulatory landscape governing AI technologies is evolving rapidly, and changes in laws, regulations or enforcement practices may impose new compliance requirements, restrict certain AI applications or increase our regulatory obligations, which could negatively impact our business.

We may be unable to realize the potential benefits of our collaboration with Dynavax.

On November 4, 2025, we entered into the License and Collaboration Agreement with Dynavax, pursuant to which we granted Dynavax an exclusive, worldwide license to develop and commercialize our oral pill COVID-19 vaccine candidate for SARS-CoV-2, SARS coronavirus or MERS coronavirus, including COVID-19 and all variants thereof. On February 10, 2026, Sanofi completed its acquisition of Dynavax. As a result of the consummation of the merger, Dynavax became an indirect wholly owned subsidiary of Sanofi.

Under the License and Collaboration Agreement, we have agreed to, among other things, continue to develop our oral pill COVID-19 vaccine candidate through completion of the ongoing Phase 2b clinical trial of such vaccine candidate. Following a planned end-of-Phase 2 meeting (“EOP2 Meeting”) with the FDA, Dynavax will have the choice, in its sole discretion, to assume responsibility for the continued development of the vaccine candidate. If Dynavax elects to undertake the continued development of our oral pill COVID-19 vaccine candidate, then we will be entitled to receive from Dynavax a fee of $50 million, subject to the terms and conditions of the License and Collaboration Agreement. The License and Collaboration Agreement further contemplates specific milestone payments payable by Dynavax to us, subject to the terms and conditions of the License and Collaboration Agreement. If Dynavax does not elect to assume responsibility for such continued development of the vaccine candidate, then the License and Collaboration Agreement will terminate pursuant to its terms.

There can be no guarantee that the collaboration with Dynavax will be successful, and we may be unable to realize in full or in part the potential benefits of such collaboration if the results of the Phase 2b clinical trial and EOP2 Meeting are unfavorable or Dynavax does not elect to assume responsibility for the continued development of our oral pill COVID-19 vaccine candidate. Even if Dynavax elects to assume responsibility for such continued development, our collaboration with Dynavax may not result in the successful development or commercialization of products or product candidates in light of the following risks: