PCVX 10-K & 10-Q changes, risk factors and insider trading

To date, we have devoted substantially all of our resources to performing research and development, undertaking preclinical studies, advancing our vaccine candidates through clinical trials, enabling manufacturing activities in support of our product development efforts, acquiring and developing our technology and vaccine candidates, organizing and staffing our company, performing business planning, establishing our intellectual property portfolio and raising capital to support and expand such activities. As an organization, we have not yet demonstrated an ability to successfully complete clinical development, obtain regulatory approvals, manufacture a commercial-scale product or conduct sales and marketing activities necessary for successful commercialization or arrange for a third party to conduct certain of these activities on our behalf. Consequently, any predictions about our future success or viability may not be as accurate as they could be if we had a longer operating history.

Our current vaccine candidate pipeline includes two clinical and three preclinical programs. We may encounter unforeseen expenses, difficulties, complications, delays, changes in the regulatory environment, and other known or unknown factors in achieving our business objectives, including with respect to our vaccine candidates. We will need to transition at some point from a company with a research and development focus to a company capable of supporting commercial activities. We may not be successful in such a transition.

As of December 31, 2024,2025, we had cash, cash equivalents and investments of $3,134.7$2,442.6 billion.million. We believe our existing cash, cash equivalents and investments will fund our current operating plans through at least 12 months from the filing date of this Annual Report on Form 10-K. However, our operating plan may change as a result of many factors currently unknown to us, and we may need to seek additional funds sooner than planned. Furthermore, we will need to raise substantial additional capital to complete the development, manufacturing and commercialization of our drug candidates. We expect to finance our cash needs through public or private equity or debt financings, third-party (including government) funding and marketing and distribution arrangements, as well as other collaborations, strategic alliances and licensing arrangements or any combination of these approaches.

Our ability to raise additional capital may be adversely impacted by potential worsening global economic conditions, including higher inflation rates andrates, changes in interest rates and the recent disruptions to and volatility in the credit and financial markets in the United States and worldwide, including the trading price of common stock, resulting from civil and political unrest in certain countries and regions. Our future capital requirements will depend on many factors, including:

•the costs of establishing additional manufacturing capacity to meet potential incremental supply requirements following the initial commercial launchlaunches of VAX-31 in the adult population and VAX-31 or VAX-24 in the pediatric population, if approved;

Our ability to raise additional funds will depend on financial, economic and other factors, many of which are beyond our control. We cannot be certain that additional funding will be available on acceptable terms, or at all. We have no committed source of additional capital and if we are unable to raise additional capital in sufficient amounts or on terms acceptable to us, we may have to significantly delay, scale back or discontinue the development or commercialization of our vaccine candidates or other research and development initiatives. Our license agreements may also be terminated if we are unable to meet the payment obligations or milestones under the agreements. We could be required to seek collaborators for our vaccine candidates at an earlier stage than otherwise would be desirable or on terms that are less favorable than might otherwise be available, or relinquish or license on unfavorable terms our rights to our vaccine candidates in markets where we otherwise would seek to pursue development or commercialization ourselves. In addition, in February 2025, the National Institutes of Health (“NIH”) announced that it would cap indirect costs for grants at 15%. If we cannot find additional funds to cover the gap created by the new funding gap, we may need to change or terminate our vaccine development program for VAX-GI, which is currently funded in part by grants obtained from the NIH and administered by the University of Maryland, Baltimore.

Due to the significant resources required for the development of our vaccine candidates, we must decide which vaccine candidates to pursue and advance and the amount of resources to allocate to each. Our decisions concerning the allocation of research, development, management and financial resources toward particular vaccine candidates may not lead to the development of any viable commercial vaccines and may divert resources away from better opportunities. For example, although we allocated resources for the development of VAX-24 in the adult population through a Phase 1/2 program, we made the determination to suspend further development of VAX-24 for the adult indication because we have chosenchose to advance exclusively VAX-31 for an adult Phase 3 program following the positive results of the VAX-31 adult Phase 1/2 study. Additionally, in August 2025, we announced that as part of our continued focus on strategic capital deployment and in order to prioritize our resources towards our PCV franchise, we had paused the advancement, beyond preclinical development, of VAX-GI while remaining confident in its potential and preserving the option to advance the program in the future. We also discontinued further development of VAX-PG, a vaccine candidate we were developing for periodontal disease, which demonstrated an acceptable safety profile but not sufficient efficacy signals to warrant further investment. Similarly, our potential decisions to delay, terminate, license or collaborate with third parties in respect of certain vaccine candidates may subsequently also prove to be less than optimal and could cause us to miss valuable opportunities. If we make incorrect determinations regarding the viability or market potential of any of our vaccine candidates or misread trends in the biopharmaceutical industry, in particular for vaccines, our business could be seriously harmed. As a result, we may fail to capitalize on viable commercial products or profitable market opportunities, be required to forego or delay pursuit of opportunities with other vaccine candidates that may later prove to have greater commercial potential than those we choose to pursue or relinquish valuable rights to such vaccine candidates through collaboration, licensing or other royalty arrangements in cases in which it would have been advantageous for us to invest additional resources to retain sole development, manufacturing and commercialization rights.

We are developing a pipeline of vaccine candidates utilizing our cell-free protein synthesis platform, which is comprised of the XpressCFTMXpressCF® platform exclusively licensed from Sutro Biopharma, Inc. (“Sutro Biopharma”) and our proprietary know-how for vaccine applications against infectious disease. Our future success depends on the successful application of this approach to vaccine development. We are in the clinical or preclinical stages of developing our vaccine candidates and there can be no assurance that any development problems we may experience in the future will not cause significant delays or unanticipated costs, or that such development problems can be overcome. For example, although we have achieved proof-of-concept for our carrier-sparing approach with VAX-31 and VAX-24, our approach may not be validated for our other vaccine candidates or subsequent trials of VAX-31 or VAX-24. We may also experience delays in developing a sustainable, reproducible and scalable manufacturing process or transferring that process to manufacturing partners, which may prevent us from completing our clinical trials or commercializing our products on a timely or profitable basis, if at all. In addition, since we have not yet completed clinical development on any of our product candidates, we do not know the specific doses that may be effective in the clinic or, if approved, commercially. Finding a suitable dose may delay our anticipated clinical development timelines. We may also encounter difficulty recruiting sufficient participants for our clinical studies, or the FDA may impose additional requirements on us regarding trial size or a long-term safety study that will significantly slow or forestall our development program.

Furthermore, our expectations with regard to our scalability and costs of manufacturing may vary significantly as we develop our vaccine candidates and learn more about these critical factors. Conjugate vaccine development is highly complex, and development of broad-valency pneumococcal conjugate vaccines (“PCVs”) is further complicated by the number of components, analytical assays and potential for adjustments, including, but not limited to, changes in raw materials, composition, formulation, manufacturing methods and dosing, which could result in drug substances and/or drug product that may vary between preclinical and clinical studies over time. Over the course of the development and manufacturing of VAX-24, we previously encountered process-related matters that required us to make adjustments to our processes. For example, in 2020 we encountered such process-related matters during our drug substance manufacturing campaign for VAX-24 at Lonza, Ltd. (“Lonza”). The cumulative impact of the time required to make adjustments to our processes led to a delay of our drug substance manufacturing campaign due to scheduling conflicts and capacity constraints at Lonza. There can be no assurance that we or Lonza will be able to successfully manufacture drug substances in a timely manner in the future, or at all. Such process changes and manufacturing delays have caused a change in our Investigational New Drug (“IND”) application timelines in the past and future changes or delays could impact future timelines for VAX-31, VAX-24 or for our other product candidates. In addition, if we encounter similar manufacturing issues after product approval, it will require inspection and approval of the new manufacturing site and submission of a Biologics License Application (“BLA”) supplement, which may further impede or delay commercialization.

In addition, the preclinical and clinical trial requirements of the FDA, European Medicines Agency (“EMA”) and other regulatory agencies and the criteria these regulators use to determine the safety and immunogenicity or efficacy of a vaccine candidate are determined according to the type, complexity, novelty and intended use and market of the potential products, taking into consideration the benefits and risks for the intended population who will receive the vaccine, as well as the disease(s) to be prevented. Regulatory agencies also evaluate a sponsor’s data to determine whether the manufacturing and facility information assure product quality and consistency. Approvals by the FDA and EMA for existing pneumococcal vaccines, such as Pfizer Inc.'s (“Pfizer”) Prevnar 13® (“PCV13”) and Prevnar 20® (“PCV20”), and Merck & Co., Inc.'s (“Merck”) VAXNEUVANCETM (“PCV15”), CapvaxiveTMCapvaxive® (“PCV21”) and Pneumovax® 23 (“PPSV23”), may not be indicative of what these regulators may require for approval of our vaccine candidates. For example, in the adult population, these existing pneumococcal vaccines were previously approved based on the establishment of non-inferiority of OPA responses relative to the then current standard of care vaccine(s), on a strain-by-strain basis, where non-inferiority was defined as greater than or equal to 0.50 of the lower limit of the two-sided 95% confidence interval of the OPA geometric mean titer ratio. Following discussions with the FDA, the non-inferiority standard in our VAX-31 adult OPUS-1 Phase 3 pivotal, noninferiority trial is set at 0.667. The FDA may challenge our VAX-31 Phase 3 Chemistry, Manufacturing and Controls (“CMC”) strategy, which could cause significant delays or unanticipated costs. Additionally, novel aspects of our vaccine candidates and manufacturing processes may create further challenges in obtaining regulatory approval. The regulatory approval process for our novel vaccine candidates can be more complex and consequently more expensive and take longer than for other, better known or extensively studied pharmaceutical or other vaccine candidates. More generally, approvals by any regulatory agency may not be indicative of what any other regulatory agency may require for approval or what such regulatory agencies may require for approval in connection with new vaccine candidates. Moreover, our vaccine candidates may not perform successfully in clinical trials. InEvolving addition, leadership of the FDA’s Center for Biologic Evaluation and Research, which oversees vaccine development, is supportive of novelregulatory approaches to vaccine development.approval If that leadership changes, wedecisions may facepresent additional hurdles to development orthat maywould havenecessitate a change to change our approach to meet regulatory expectations.

Our ability to achieve and sustain profitability depends on obtaining regulatory approvals for and successfully commercializing our vaccine candidates, either alone or with third parties, and we cannot guarantee that we will ever obtain regulatory approval for any of our vaccine candidates. We have limited experience in conducting and managing the clinical trials necessary to obtain regulatory approvals, including approval by the FDA. None of our vaccine candidates have been the subject of late-stage or pivotal clinical trials,FDA, and we may never be able to obtain marketing approval for any of our product candidates. Before obtaining regulatory approval for the commercial distribution of our vaccine candidates, we must conduct extensive preclinical studies and clinical trials to demonstrate the safety and immunogenicity or efficacy of our vaccine candidates.

In addition, changes to the standard-of-care or the approval standards for new vaccines have, and could again in the future, change the threshold for achievement of non-inferiority using the established surrogate immune endpoints that our PCVs will need to meet in our clinical trials.

Our business is highly dependent on the success of our PCV candidates, VAX-31 and VAX-24, both of which are in clinical development.candidates. If we are unable to successfully develop, obtain approval for and effectively commercialize VAX-31our orPCV VAX-24,candidates, our business would be significantly harmed.

Our business and future success depends on our ability to successfully develop, obtain regulatory approval of, and then commercialize our PCV candidates, which include VAX-31, our 31-valent clinical PCV candidate in development for both the adult and pediatric populations, and VAX-24, our 24-valent clinical PCV candidate in development for the pediatric population.population, and VAX-XL, our third-generation PCV candidate designed to provide the broadest coverage of any PCV currently in development. Although VAX-31 has produced positive topline results in a Phase 1/2 clinical study in adults, it may not demonstrate the same results in futurethe adult pivotal Phase 3 studiesstudy needed to obtain marketing approval from the FDA or comparable foreign regulatory authorities or in infant clinical studies. In addition, past VAX-24 results in adults may not be indicative of future results in infant clinical trials. VAX-31 and VAX-24 will require additional clinical and non-clinical development, regulatory review and approval in multiple jurisdictions, substantial investment, access to sufficient clinical and commercial manufacturing capacity and significant marketing efforts before we can generate any revenue from product sales. We cannot provide any assurance that we will be able to successfully advance VAX-31our andPCV VAX-24candidates through the development process.

•our ability to demonstrate to the satisfaction of the FDA or comparable foreign regulatory authorities the safety and immunogenicity or efficacy and acceptable risk to benefit profile of VAX-31,our VAX-24PCV candidates and any future vaccine candidates;

•the pace and prevalence of serotype replacement following the introduction of VAX-31,our VAX-24PCV candidates or other vaccines targeting pneumococcal disease;

•obtaining and maintaining an Advisory Committee on Immunization Practices (“ACIP”) preferred recommendation or, comparable foreign regulatory authority’sauthority, professional society, or other clinical recommendation of our vaccine candidates and the willingness of physicians, operators of clinicsclinics, and patients to utilize or adopt any of our future vaccine candidates to prevent or treat age-associated diseases;

Vaccine candidates that we successfully develop and commercialize may compete with existing vaccines and new vaccines that may become available in the future. Many of our competitors have substantially greater financial, lobbying, technical, human and other resources than we do and may be better equipped to develop, manufacture and market technologically superior vaccines, including the potential that our competitors may develop chemical processes or utilize novel technologies for developing vaccines that may be superior to those we employ. In addition, many of these competitors have significantly greater experience than we have in undertaking preclinical studies and clinical trials of new products and in obtaining regulatory approvals, including for many vaccine franchises. Accordingly, our competitors may succeed in obtaining FDA approval or a preferred recommendation from ACIP for their products. For example, PCV13 obtained FDA approval for the prevention of invasive pneumococcal disease (“IPD”) in infants based on non-inferior IgG antibody responses relative to Prevnar, using the surrogate immune endpoints established by the prior Prevnar field efficacy study. Pfizer implemented a similar approach to the development of its 20-valent PCV vaccine candidate, PCV20, which was approved by the FDA in June 2021 for use in adults and in April 2023 for use in infants and children. Pfizer announced in July 2024 and October 2024 that it is developing a 25-valent PCV candidate ("PCV25") that is currently in adult and pediatric Phase 2 clinical trials.trials, Pfizer also announced in October 2024and that it is working on a 30-plus valent PCV candidate that is in preclinical development. Pfizer announced in November 2025 that it plans to initiate adult and pediatric pivotal trials evaluating PCV25 in 2026. Merck received approval for PCV15, its 15-valent PCV, in July 2021 for use in adults and in June 2022 for use in infants and children. Merck announced in June 2024 that PCV21, its 21-valent PCV, received approval from the FDA for use in adults. In September 2025, Merck announced positive results from its Phase 3 study evaluating PCV21 in children aged 2–17 with increased risk for pneumococcal disease. Merck is also advancing additional next-generation PCV candidates through multiple early-phase clinical studies evaluating different formulations. In addition, Sanofi and SK Chemicalsbioscience have partnered to develop a 21-valent PCV and, in June 2023, announced positive results from their Phase 2 clinical trials in infants. In December 2024, Sanofi and SK Chemicalsbioscience announced the initiation of a global pediatric Phase 3 clinical studyprogram of their 21-valent PCV candidate, as well as an expanded agreement to develop, license and commercialize "next-generation" PCVs for both pediatric and adult populations. In February 2026, SK bioscience announced that it expected topline results from this Phase 3 study to be available in 2027, and that a next-generation PCV candidate, also co-developed with Sanofi, was in preclinical development with clinical trial entry expected in 2026. GSK, which previously acquired Affinivax, iswas previously developing a 24-valent24‑valent affinity-boundaffinity‑bound pneumococcal vaccine for infants, which is currentlycandidate in aadults pediatricand Phase 2 clinical trial with data anticipated in 2026 or later.infants. In October 2024, GSK announced they have ceased the developmenttermination of their adult 24-valent program in adults in favor of a preclinical 30-plus valent candidate. In October 2025, GSK announced the initiation of a Phase 1 study in Australia evaluating its 30-plus valent candidate in adults. In the fourth quarter of 2025, GSK removed its pediatric 24-valent candidate, which had previously advanced into a Phase 2 clinical trial program, from its publicly disclosed pipeline.

While we are designing and developing a manufacturing process that we believe can scale to address clinical and commercial vaccine supply, we do not own or operate any manufacturing facilities. We rely on contract manufacturing organizations (“CMOs”), including our strategic partnership with our contract manufacturer, Lonza, to access resources to facilitate the development and, if approved, commercialization of VAX-31 or VAX-24 and our other vaccine candidates. Advancing our vaccine candidates may create significant challenges for our CMOs, including:

Before we can initiate a clinical trial or commercialize any of our vaccine candidates, we must demonstrate to the FDA that the CMC for our vaccine candidates meet applicable requirements, and prior to authorization in the European Union (“EU”), a manufacturing authorization must be obtained from the appropriate EU regulatory authorities. Because no product manufactured on a cell-free manufacturing platform has been approved in the United States, there is no manufacturing facility that has demonstrated the ability to comply with FDA requirements, and, therefore, the timeframe for demonstrating compliance to the FDA’s satisfaction is uncertain. Personnel changes at regulatory agencies could impact or delay the timing of pre-approval inspections or the issuance of required authorizations. Delays in establishing our manufacturing process and ensuring the facilities we utilize for manufacturing comply with cGMP or disruptions in our manufacturing processes, implementation of novel technologies or scale-up activities, may delay or disrupt our development efforts.

•receiving the U.S. Centers for Disease Control and Prevention (“CDC”), and ACIP recommendations for use, as well as recommendations ofACIP, comparable foreign regulatory andauthority, advisoryprofessional bodiessociety, or other clinical recommendation for use;

In the United States, the CDC and ACIP develop vaccine recommendations for both children and adults, as do professional societies and similar agencies around the world. To develop its recommendations, the ACIP forms working groups that gather, analyze and prepare scientific information. The ACIP also considers many of the factors above, as well as myriad additional factors such as the value of vaccination for the target population regarding the outcomes, health economic data and implementation issues. The ACIP recommendations are also made within categories, such as in an age group or a specified risk group. For example, the ACIP may determine that a preferred recommendation in a smaller child population may be more economical than recommending vaccinations for a larger adult population, which could adversely impact our market opportunity.

The membershipACIP's ofcomposition and decisions could influence the ACIPpathway is influenced by the Department of Health and Human Services (“HHS”). Changes in the ACIP representation could impact the viability offor new vaccines receivingto receive a positive recommendation,recommendation particularlyor ifthe thereimpact isof a changepositive in the federal government’s posture towards vaccines.recommendation. If our vaccine candidates are approved but fail to receive CDCCDC, andACIP, ACIPcomparable foreign authority, professional society, or other clinical recommendations, or recommendationsfail of other comparable foreign regulatory and advisory bodies, orto achieve market acceptance among physicians, healthcare providers, patients, third-party payors or others in the medical community, we will not be able to generate significant revenue. Even if our products achieve market acceptance, we may not be able to maintain that market acceptance over time if new products or technologies are introduced that are more favorably received than our products, are more cost effective or render our products obsolete.

The success of our business depends in large part upon our ability to identify, develop and commercialize products based on our cell-free protein synthesis platform. WeIn intendaddition to pursueour clinicalPCV developmentfranchise, ofour additionalpipeline includes preclinical vaccine candidates beyond VAX-31 and VAX-24 for IPD, including VAX-A1 for Group A Streptococcus (“Group A Strep”), VAX-PG for periodontitis and VAX-GI for dysentery and shigellosis. Our research programs may fail to identify potential vaccine candidates for clinical development for a number of reasons or we may focus our efforts and resources on potential programs or vaccine candidates that ultimately prove to be successful in a smaller subset of patients than expected or completely unsuccessful. In addition, we cannot provide any assurance that we will be able to successfully advance any of our existing or future vaccine candidates through the development process.

We currently rely on third-party manufacturing and supply partners, including Lonza and Sutro Biopharma,partners to supply raw materials and components for, and the manufacture of, our preclinical and clinical supplies as well as our vaccine candidates. Our inability to procure necessary raw materials or to have sufficient quantities of preclinical and clinical supplies or the inability to have our vaccine candidates manufactured, including delays or interruptions at our third-party manufacturers, or our failure to comply with applicable regulatory requirements or to supply sufficient quantities at acceptable quality levels or prices, or at all, would materially and adversely affect our business.

We rely on third-party contract manufacturers to manufacture preclinical and clinical trial product materials and supplies for our needs. There can be no assurance that our preclinical and clinical development product supplies will not be limited or interrupted or be of satisfactory quality or continue to be available on acceptable terms. Over the course of the development and manufacturing of VAX-24, we previously encountered process-related matters that required us to make adjustments to our processes. For example, in 2020 we encountered such process-related matters during our drug substance manufacturing campaign for VAX-24 at Lonza. The cumulative impact of the time required to make adjustments to our processes led to a delay of our drug substance manufacturing campaign due to scheduling conflicts and capacity constraints at Lonza. There can be no assurance that we or Lonza will be able to successfully manufacture drug substances in a timely manner in the future, or at all. Such process changes and manufacturing delays have caused a change in our IND timelines in the past and future changes or delays could impact future timelines for VAX-31, VAX-24, or for our other product candidates. Since we utilize a third-party manufacturer,manufacturers, we are also subject to Lonza’stheir scheduling commitments for itstheir other clients. Scheduling conflicts with Lonza’s other clients have contributed to manufacturing delays in the past, and there is no guarantee that future scheduling conflicts or related capacity constraints will not affect our manufacturing campaigns and related timelines. Certain aspects of our manufacturing process for our clinical trial product materials and supplies have also been adversely affected by macroeconomic factors in the past and may in the future be adversely affected by these and numerous other factors, including earthquakes and other natural or man-made disasters, economic downturns, equipment failures, labor shortages, health epidemics, power failures and tariffs.significant changes in trade policies.

If our contract manufacturers cannot successfully manufacture material that conforms to our specifications and the strict regulatory requirements of the FDA or comparable foreign regulatory authorities, or if they cannot pass a pre-approval inspection, we may not be able to rely on their manufacturing facilities for the manufacture of elements of our vaccine candidates. Moreover, we do not control the manufacturing process at our contract manufacturers and are completely dependent on them for compliance with current regulatory requirements. In the event that any of our manufacturers failsfail to comply with such requirements or to perform itstheir obligations in relation to quality, timing or otherwise, or if our supply of components or other materials becomes limited or interrupted for other reasons, we may be forced to manufacture the materials ourselves or enter into an agreement with another third party, which we may not be able to do on reasonable terms, if at all. In some cases, the technical skills, raw materials or technology required to manufacture our vaccine candidates may be unique or proprietary to the original manufacturer or supplier, and we may have difficulty applying such skills or technology or sourcing such raw materials ourselves, or in transferring such skills, technology or raw materials to another third party, or such transfer may be subject to certain consent obligations and payment terms to Lonza.the original manufacturer. These factors would increase our reliance on such manufacturer or require us to obtain a license from such manufacturer in order to enable us, or to have another third party, manufacture our vaccine candidates. If we are required to change manufacturers for any reason, we will be required to verify that the new manufacturer maintains facilities and procedures that comply with quality standards and with all applicable regulations and guidelines, and we may be required to repeat some of the development program and submit a supplement to our application. The delays associated with the verification of a new manufacturer could negatively affect our ability to develop vaccine candidates in a timely manner or within budget.

We expect to continue to rely on third-party manufacturers and suppliers, including Lonza,suppliers if we receive regulatory approval for any PCV or any other vaccine candidates. For example, in October 2023, we entered into a pre-commercial services and commercial manufacturing supply agreement (the “Lonza Commercial Manufacturing and Supply Agreement”) with Lonza, pursuant to which Lonza will (i) construct and build out a dedicated suite (“Suite”) at Lonza’s facilities in Visp, Switzerland to manufacture certain key components (including drug substance) for our proprietary PCV franchise and any other products or intermediates we may choose (collectively, the “Products”), and (ii) maintain and operate the Suite (utilizing Lonza’s employees) to manufacture the Products as a service provided to us, including conducting related quality control and quality assurance operations. PursuantIn September 2025, we also entered into a master services agreement with Patheon Manufacturing Services LLC, part of Thermo Fisher Scientific (collectively, “Thermo Fisher”), pursuant to which Thermo Fisher will commercially manufacture and supply drug product for our PCV candidates, if approved (the “Thermo Fisher Commercial Manufacturing and Supply Agreement, Lonza will be a preferred, non-exclusive, supplier of the Products to us, and we retain the right to procure the Products from one or more alternate and/or backup manufacturers of the Products (including at our own facilitiesAgreement”).

To the extent that we have existing, or enter into future, manufacturing arrangements with third parties, we will depend on these third parties to perform their obligations in a timely manner consistent with contractual and regulatory requirements, including those related to quality control and assurance. In December 2019, we exercised our right to require Sutro Biopharma to establish a second supplier for extract and custom reagents to support our anticipated clinical and commercial needs. In December 2022, we entered into an option grant agreement with Sutro Biopharma (the “Option Agreement”). Pursuant to the Option Agreement, we acquired from Sutro Biopharma (i) authorization to enter into an agreement with an independent alternate CMO to directly source Sutro Biopharma’s cell-free extract, allowing us to have direct oversight over financial and operational aspects of the relationship with the CMO; and (ii) a right, but not an obligation, to obtain certain exclusive rights to internally manufacture and/or source extract from certain CMOs and the right to independently develop and make improvements to extract (including the right to make improvements to the extract manufacturing process as well as cell lines) for use in connection with the exploitation of certain vaccine compositions (the “Option”). We and Sutro Biopharma agreed to negotiate the terms and conditions of a form definitive agreement to be entered into in the event we exercise the Option, which would include the terms and conditions set forth in an executed term sheet between us (the “Term Sheet”) and such terms that were necessary to give effect to each of the terms and conditions set forth in the Term Sheet (the “Form Definitive Agreement”). On September 28, 2023, we and Sutro Biopharma mutually agreed in writing upon the Form Definitive Agreement to become effective in the event that we exercise the Option. In November 2023, we exercised the Option and entered into a manufacturing rights agreement (the “Manufacturing Rights Agreement”) with Sutro Biopharma to obtain control over the development and manufacture of cell-free extract. Pursuantpursuant to the Manufacturing Rights Agreement,which we obtained exclusive rights to independently, or through certain third parties, develop, improve and manufacture cell-free extract for use in connection with our vaccine candidates. If Sutro Biopharma, the independent alternate CMO or the designated third parties are unable to provide a sufficient supply of cell-free extract, our third-party manufacturers may be delayed in their production of intermediate components, which may lead to delays of our drug substance manufacturing campaigns.

Increases in negative perceptions of vaccines or the technologies that we rely on by regulators may result in the FDA not approving our products or, if approved, fewer physicians prescribing our products. It also may reduce the willingness of patients to utilize our products or participate in clinical trials for our vaccine candidates.

For example, based on the positive topline results from the VAX-24 Phase 1/2 proof-of-concept study, which evaluated the safety, tolerability and immunogenicity of VAX-24 in adults 18-64 years of age, the FDA supported the initiation of a pediatric study in infants. This study could uncover risks in this study population that could have potentially been discovered during a child and/or toddler study, which could then delay or stop the completion of clinical development. Any inability to successfully complete preclinical and clinical development could result in additional costs to us or impair our ability to generate revenue. In addition, if we make manufacturing or formulation changes to our vaccine candidates, we may be required to or we may elect to conduct additional studies to bridge our modified vaccine candidates to earlier versions. Clinical trial delays could also shorten any periods during which our products have patent protection and may allow our competitors to bring products to market before we do, which could impair our ability to successfully commercialize our vaccine candidates and may harm our business and results of operations.

We may experience difficulties in enrolling subjects in any clinical trials we may conduct for a variety of reasons. The timely completion of clinical trials in accordance with their protocols depends, among other things, on our ability to enroll a sufficient number of subjects who remain in the study until its conclusion. The enrollment of subjects depends on many factors, includingincluding, but not limited to:

Based on our VAX-24VAX-31 End-of-Phase 2 meeting with the FDA in October 2023,FDA, we believe there was agreement with the FDA on the clinical design of the then planned VAX-24 adult Phase 3 program, including the approximate overall number of subjects, the primary and secondary endpoints for the pivotal, non-inferiority study as well asis confirmation that the planned immunogenicity analyses would have beenare sufficient to support licensure and an efficacy study is therefore would not have been required. Following the topline results of the VAX-31 Phase 1/2 study in adults 50 and older, we selected VAX-31 to exclusively advance to an adult Phase 3 program. We plan to hold an End-of-Phase 2 meeting for the VAX-31 adult program in advance of commencing a Phase 3 program. However, we believe the FDA position related to the previously discussed VAX-24 adult Phase 3 program will also apply to the VAX-31 adult Phase 3 program. In the event that we are required to conduct any field efficacy studies for VAX-31 or any of our other product candidates, enrollment of a sufficient number of subjects may require additional time and resources given widespread vaccination rates in the United States, particularly in the pediatric population. As a result, we may be required to conduct any such trials outside the United States, which could cause additional complexity and delay. Delays in enrollment may result in increased costs or may affect the timing or outcome of any clinical trials we may conduct, which could prevent completion of these trials and adversely affect our ability to advance the development of our vaccine candidates.

From time to time, we may publish interim topline or preliminary data from our preclinical or clinical trials. Interim topline data from clinical trials that we may complete are subject to the risk that one or more of the clinical outcomes may materially change as more patient data become available. We also make assumptions, estimations, calculations and conclusions as part of our analyses of data, and we may not have received or had the opportunity to fully and carefully evaluate all data when we publish such data. As a result, the topline results that we report may differ from future results of the same studies, or different conclusions or considerations may qualify such results once additional data have been received and fully evaluated. Preliminary or topline data also remain subject to audit and verification procedures that may result in the final data being materially different from the preliminary data we may publish. As a result, interim and preliminary data should be viewed with caution until the final data are available. Adverse differences between preliminary or interim data and final data could significantly harm our business prospects. Additionally, disclosure of interim topline or preliminary data by us or by our competitors has and may continue to result in volatility in the price of our common stock.

We have in the past and may in the future seek BTD or Fast Track designation for some of our vaccine candidates. For instance, in August 2022 we announced that the FDA granted Fast Track designation to VAX-24 in adults ages 18 and older and,older, in January 2023,2023 we announced that the FDA granted a BTD for VAX-24 for the prevention of IPD in adults, in November 2024 we announced that the FDA granted a BTD for VAX-31 for the prevention of IPD in adults, and in August 2025 we announced that the FDA extended the BTD for VAX-31 to include the prevention of pneumonia caused by Streptococcus pneumoniae in adults. A sponsor may seek FDA designation of its vaccine candidate as a breakthrough therapy if the vaccine candidate is intended to treat a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the therapy may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. For vaccines that have been designated as Breakthrough Therapies, the FDA may take actions to expedite the development and review of the application, and interaction and communication between the FDA and the sponsor of the trial can help to identify the most efficient path for clinical development while minimizing the number of patients placed in ineffective control regimens.

Even whenif we obtain Fast Track designation for one or more of our vaccine candidates, we may not experience a faster development process, review or approval compared to non-expedited FDA review procedures. In addition, the FDA may withdraw Fast Track designation from any of our vaccine candidates that may receive the designation in the future, if it believes that the designation is no longer supported. Fast Track designation alone does not guarantee qualification for the FDA’s Priority Review procedures.

We currently have no sales, marketing or distribution capabilities and as an organization have no experience in marketing products. If we develop an in-house marketing organization and sales force, we will require significant capital expenditures,expenses, management resources and time, and we will have to compete with other pharmaceutical and biotechnology companies to recruit, hire, train and retain marketing and sales personnel.

A variety of risks associated with potentiallyour conducting researchcurrent and clinicalpotential trialsinternational abroadoperations and marketing our vaccine candidates internationallycollaborations could materially adversely affect our business.

As we pursue approval and commercialization for our vaccine candidates overseas and conduct CMC and other operations overseas, we will be subject to additional risks related to operating in foreign countries, includingincluding, but not limited to:

As our discovery, development, manufacturing and commercialization plans and strategies develop, we have rapidly expanded our employee base and expect to continue to add managerial, operational, sales, research and development, marketing, financial and other personnel. Current and future growth imposes significant added responsibilities on members of management, includingincluding, but not limited to:

If our information technology systems or those of the third parties upon which we rely, are or were compromised, we could experience adverse consequences resulting from such compromise, includingincluding, but not limited toto, significant fines or other liability; regulatory investigations or actions; disruptions of our development programs or business operations; harms to our reputation,reputation; and other adverse consequences.

We and the third parties upon which we rely are subject to a variety of evolving threats, includingincluding, but not limited toto, software bugs; malicious code (such as viruses and worms); social-engineering attacks (including through deep fakes, which may be increasingly more difficult to identify as a fake, and phishing attacks); employee error, theft or misuse; denial-of-service attacks (such as credential stuffing); malware (including as a result of advanced persistent threat intrusions); natural disasters; terrorism; war; telecommunication and electrical failures; supply-chain attacks; ransomware attacks; attacks enhanced or facilitated by artificial intelligence (“AI”); and other similar threats. In particular, severe ransomware attacks, including those perpetrated by organized criminal threat actors, nation-states, and nation-state-supported actors, are becoming increasingly prevalent and can lead to significant interruptions in our operations, loss of data and income, reputational harm and diversion of funds. Extortion payments may alleviate the negative impact of a ransomware attack, but we may be unwilling or unable to make such payments due to, for example, applicable laws or regulations prohibiting such payments. We may also be the subject of server malfunction, software or hardware failures, supply-chain cyberattacks, loss of data or other computer assets and other similar issues.

We cannot be sure that our insurance coverage, if any, will be adequate or otherwise protect us from or adequately mitigate liabilities or damages with respect to claims, costs, expenses, litigation, fines, penalties, business loss, data loss, regulatory actions or other materially adverse impacts arising out of our processing activities, privacy and security practices, or security breaches we may experience. The successful assertion of one or more large claims against useus that exceeds our available insurance coverage, or results in changes to our insurance policies (including premium increases or the imposition of large excess or deductible or co-insurance requirements), could result in substantial cost increase or prevent us from obtaining insurance on acceptable terms. Additionally, our contracts may not contain limitations of liability, and even where they do, there can be no assurance that limitations of liability in our contracts are sufficient to protect us from liabilities, damages, or claims related to our data privacy and security obligations.

Our operations, and those of our CMOs, CROs and other contractors and consultants, could be subject to earthquakes, power shortages, telecommunications failures, water shortages, floods, hurricanes, typhoons, fires, extreme weather conditions, medical epidemics and other natural or man-made disasters or business interruptions, for which we are predominantly self-insured. The impact of climate change may increase these risks due to changes in weather patterns, such as increases in storm intensity, sea-level rise, melting of permafrost and temperature extremes on facilities or operations. The occurrence of any of these business disruptions could seriously harm our operations and financial condition and increase our costs and expenses.

The American Rescue Plan Act (“ARPA”) was signed on March 11, 2021. One of the provisions of the ActARPA included a modification to the provision limiting the deductibility of executive compensation expense, expanding the definition of covered employees subject to IRC 162(m) to include an additionalthe top five highest compensated employees beyond the CEO, CFO and three highest paid officersofficers. currentlyThe coveredprovision was further modified by the OBBBA, which made the provision applicable to publicly traded companies and all members of their controlled group (as opposed to members of the affiliated group, as prescribed under IRCprior 162(mlaw). ThisAll expandedchanges provisionare is applicableeffective for tax years beginning after December 31, 2026.2025. WeWhile we do not believe that thisthese updatemodifications to IRC 162(m) wouldwill have a material impact on our income tax provision currentlycurrently, andwe will continue to monitor this provision.

Our ability to utilize our net operating loss ("NOL") carryforwards and certain other tax attributes may be limited.

We have incurred substantial losses since inception and do not expect to become profitable in the near future, if ever. As of December 31, 2024,2025, we had federal and state NOL carryforwards of $430.2$796.1 million and $1,188.1$1,907.7 million, respectively. The federal and state loss carryforwards, except the federal loss carryforward arising in tax years beginning after December 31, 2017, begin to expire in 2034 unless previously utilized. Federal NOLs arising in tax years beginning after December 31, 2017 have an indefinite carryforward period and do not expire. As of December 31, 2024,2025, we also had federal and state research credit carryforwards of $28.3$40.3 million and $8.1$12.3 million, respectively. The federal research and development tax credit carryforwards expire beginning in 2039 unless previously utilized, and the state research and development tax credits can be carried forward indefinitely. In general, under Sections 382 and 383 of the U.S. Internal Revenue Code of 1986, as amended, a corporation that undergoes an “ownership change” (generally defined as a greater than 50 percentage point change (by value) in its equity ownership by certain stockholders over a rolling three-year period) is subject to limitations on its ability to utilize its pre-change NOLs to offset future taxable income. We have experienced ownership changes in the past. There were no ownership changes identified in 2024,2025, as such we have determined that no federal research credits will expire unutilized or are excluded from our research carryforwards as of December 31, 2024.2025. Subsequent ownership changes may affect the limitation in future years. As a result, if, and to the extent that we earn net taxable income, our ability to use our pre-change NOLs to offset such taxable income may be subject to limitations.

We are a clinical-stage vaccine innovation company engineering high-fidelity vaccines to protect humankind from the consequences of bacterial diseases. We are developing broad-spectrum conjugate and novel protein vaccines to prevent or treat bacterial infectious diseases. We are re-engineering the way highly complex vaccines are made through modern synthetic techniques, including advanced chemistry and the XpressCF™ cell-free protein synthesis platform, exclusively licensed from Sutro Biopharma, Inc. (“Sutro Biopharma”).platform. Unlike conventional cell-based approaches, our system for producing difficult-to-make proteins and antigens is intended to accelerate our ability to efficiently createdevelop and deliver high-fidelity vaccines with enhanced immunological benefits.benefits that are beyond the capabilities of conventional approaches.

•Pneumococcal conjugate vaccine (“PCV”) candidates that we believe are among the broadest-spectrum PCV candidates currently in development, targeting the approximately $8 billion global pneumococcal vaccine market. Pneumococcal disease ("PD") is an infection caused by Streptococcus pneumoniae bacteria. It can result in invasive pneumococcal disease (“IPD”), including meningitis and bacteremia, and non-invasive pneumococcal disease,PD, including pneumonia, otitis media and sinusitis. Our broad-spectrum, carrier-sparing PCV candidates, VAX-31VAX-31, VAX-24 and VAX-24,VAX-XL, are designed to improve upon the standard-of-care PCVs for both adults and children by covering the serotypes that are responsible for aincreasing significant portionportions of IPD in circulation and are associated with high case-fatality rates, antibiotic resistance and meningitis, while maintaining coverage of previously circulating strains that are currently contained through continued vaccination practice.vaccination.

▪VAX-31 is a 31-valent, broad-spectrum, carrier-sparing investigational PCV being developed for the prevention of IPD.IPD and pneumonia. VAX-31 is the broadest-spectrum PCV in the clinic, and has the potential to provide protection against both currently circulating and historically prevalent serotypes. VAX-31 was designed to increase coverage, in a single vaccine, to more thanapproximately 95% of IPD and approximately 88% of pneumococcal pneumonia circulating in adults in the United States aged 50 and older, with the potential to provide an incremental 12-40%14-34% of coverage for IPD and an incremental 19-31% of coverage for pneumococcal pneumonia over current standard-of-care adult PCVs.

•In November 2024, we announced that the FDA granted a breakthrough therapy designation ("BTD") for VAX-31 for the prevention of IPD in adults.adults and, in August 2025, we announced that the FDA expanded the BTD for VAX-31 to include the prevention of pneumonia caused by Streptococcus pneumoniae.

•VAX-A1, a novel conjugate vaccine candidate designed to prevent disease caused by Group A Streptococcus (“Group A Strep”). Group A Strep is pervasive globally and causes an estimated 800 million cases of illness annually, including pharyngitis, or strep throat, and certain severe invasive infections and sequelae. There is currently no vaccine against Group A Strep, which is one of the leading infectious disease-related causes of death and disability worldwide and a significant contributor to the prescription of antibiotics in children. We believe we have demonstrated preclinical proof of concept for VAX-A1, the data for which were published in December 2020. We nominatedplan theto finalinitiate vaccinea candidatePhase 1 adult study for VAX-A1 in 2026, with the firstprimary quarterobjective of 2021assessing safety and initiated Investigational New Drug ("IND")-enabling activities in the second half of 2021. We continue to advance the development of VAX-A1 and we intend to provide further information about the anticipated timing of an IND application as the program progresses.tolerability.

•VAX-GI, a novel preclinical vaccine candidate being developed as a preventative treatment for dysentery and shigellosis, which is caused by Shigella bacteria. Shigella is a bacterial illness estimated to cause 80 million to 165 million cases of disease and 600,000 deaths annually, mostly among children. The central antigen in VAX-GI is IpaB, a well-appreciated antigen that other developers have been unable to produce in an amount sufficient to enable a commercial product. With our cell-free technology, we believe we can produce this antigen at substantially improved yields, allowing for commercial-scale production. VAX-GI is being developed in collaboration with the University of Maryland, Baltimore as well as with partial funding from two research grants awarded by the National Institutes of Health (“NIH”). As part of our continued focus on strategic capital deployment and in order to prioritize our resources towards our PCV franchise, we announced in August 2025 that we had paused the advancement, beyond preclinical development, of VAX-GI while remaining confident in its potential and preserving the option to advance the program in the future.

•Completed Public Offering Generating Gross Proceeds of $632.5 million: In February 2024,2026, we completed an underwritten public offering of 12,695,31212,650,000 shares of our common stock, which included the full exercise of the underwriters’underwriters' option to purchase an additional 1,757,8121,650,000 shares, at a public offering price of $64.00$50.00 per share and pre-funded warrants to purchase 781,250 shares of our common stock at a public offering price of $63.999 per underlying share. The aggregate gross proceeds to us from thethis offering were $862.5$632.5 million, before deducting underwriting discounts and commissions and other estimated offering expenses payable by us, and excluding the exercise of any pre-funded warrants.us.

We have incurred net losses in each year since inception and expect to continue to incur net losses in the foreseeable future. Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending in large part on the timing of our preclinical studies, clinical trials and manufacturing activities, and our expenditures on other research and development activities. Our net losses were $766.6 million, $463.9 million, $402.3 million and $223.5$402.3 million for the years ended December 31, 2024,2025, 20232024 and 2022,2023, respectively. As of December 31, 2024,2025, we had an accumulated deficit of $1,388.3$2,154.9 million and cash, cash equivalents and investments of $3,134.7$2,442.6 million. We believe our cash, cash equivalents and investments will be sufficient to fund our operating expenses and capital expenditure requirements through at least 12 months from the filing date of this Annual Report on Form 10-K.

We are a clinical-stage biotechnology vaccine company. Investment in clinical-stage companies and vaccine development is highly speculative because it entails substantial upfront capital expenditures and significant risk that any potential vaccine candidate will not gain regulatory approval or become commercially viable. We do not have any products approved for sale and have not generated any revenue from product sales. As a result, we are not profitable and have incurred losses in each year since inception. Our net losses were $766.6 million and $463.9 million for the years ended December 31, 2025 and 2024, respectively, and $320.6$284.3 million and $140.7$166.6 million for the three months ended MarchJune 31,30, 2026 and 2025, respectively, and $604.9 million and $307.3 million for the six months ended June 30, 2026 and 2025, respectively. As of MarchJune 31,30, 2026, we had an accumulated deficit of $2.5$2.8 billion.

As of MarchJune 31,30, 2026, we had cash, cash equivalents and investments of $2.7$2.5 billion. We believe our existing cash, cash equivalents and investments will fund our current operating plans through at least 12 months from the filing date of this Quarterly Report on Form 10-Q. However, our operating plan may change as a result of many factors currently unknown to us, and we may need to seek additional funds sooner than planned. Furthermore, we will need to raise substantial additional capital to complete the development, manufacturing and commercialization of our drug candidates. We expect to finance our cash needs through public or private equity or debt financings, third-party (including government) funding and marketing and distribution arrangements, as well as other collaborations, strategic alliances and licensing arrangements or any combination of these approaches.

Vaccine candidates that we successfully develop and commercialize may compete with existing vaccines and new vaccines that may become available in the future. Many of our competitors have substantially greater financial, lobbying, technical, human and other resources than we do and may be better equipped to develop, manufacture and market technologically superior vaccines, including the potential that our competitors may develop chemical processes or utilize novel technologies for developing vaccines that may be superior to those we employ. In addition, many of these competitors have significantly greater experience than we have in undertaking preclinical studies and clinical trials of new products and in obtaining regulatory approvals, including for many vaccine franchises. Accordingly, our competitors may succeed in obtaining FDA approval or a preferred recommendation from ACIP for their products. For example, PCV13 obtained FDA approval for the prevention of invasive pneumococcal disease (“IPD”) in infants based on non-inferior IgG antibody responses relative to Prevnar, using the surrogate immune endpoints established by the prior Prevnar field efficacy study. Pfizer implemented a similar approach to the development of its 20-valent PCV vaccine candidate, PCV20, which was approved by the FDA in June 2021 for use in adults and in April 2023 for use in infants and children. Pfizer previously announced that it was developing a 25-valent PCV candidate ("PCV25") that was in adult and pediatric Phase 2 clinical trials, and that it was working on a 30-plus valent PCV candidate that was in preclinical development. Pfizer announced in November 2025 that it planned to initiate adult and pediatric pivotal trials evaluating PCV25 in 2026. In May 2026, Pfizer announced the initiation of a Phase 3 pediatric studyprogram evaluating PCV25 and thatthe termination of its adult 25-valent program wasin advancingfavor directly toof a preclinical 35-valent candidate, which it expects will enter clinical development in 2026. Merck received approval for PCV15, its 15-valent PCV, in July 2021 for use in adults and in June 2022 for use in infants and children. Merck announced in June 2024 that PCV21, its 21-valent PCV, received approval from the FDA for use in adults. In September 2025, Merck announced positive results from its Phase 3 study evaluating PCV21 in children aged 2–17 with increased risk for pneumococcal disease. In June 2026, Merck announced that the FDA approved an additional indication for PCV21 in children aged 2–17 with increased risk of pneumococcal disease who have previously completed a primary pediatric pneumococcal series. Merck is also advancing additional next-generation PCV candidates through multiple early-phase clinical studies evaluating different formulations. In addition, Sanofi and SK bioscience have partnered to develop a 21-valent PCV and, in June 2023, announced positive results from their Phase 2 clinical trials in infants. In December 2024, Sanofi and SK bioscience announced the initiation of a global pediatric Phase 3 clinical program of their 21-valent PCV candidate, as well as an expanded agreement to develop, license and commercialize "next-generation" PCVs for both pediatric and adult populations. In February 2026, SK bioscience announced that it expected topline results from this Phase 3 study to be available in 2027, and that a next-generation PCV candidate, also co-developed with Sanofi, was in preclinical development with clinical trial entry expected in 2026. In March 2026, SK bioscience announced that it was targeting 2029 for commercialization of its 21-valent PCV candidate, which it is co-developing with Sanofi. GSK, which previously acquired Affinivax, was previously developing a 24‑valent affinity‑bound pneumococcal vaccine candidate in adults and infants. In October 2024, GSK announced the termination of their adult 24-valent program in favor of a preclinical 30-plus valent candidate. In October 2025, GSK announced the initiation of a Phase 1 study in Australia evaluating its 30-plus valent candidate in adults. In the fourth quarter of 2025, GSK removed its pediatric 24-valent candidate, which had previously advanced into a Phase 2 clinical trial program, from its publicly disclosed pipeline.

As a result of these factors, our competitors may obtain regulatory approval of their products before we are able to, which may limit our ability to develop or commercialize our vaccine candidates, or achieve a competitive position in the market. This would adversely affect our ability to generate revenue. Our competitors may also develop vaccines that are safer, more effective, more widely accepted or less expensive than ours, and may also be more successful than we are in manufacturing and marketing their products. These advantages could render our vaccine candidates obsolete or non-competitive before we can recover the costs of such vaccine candidates’ development, manufacturing and commercialization.

The success of our business depends in large part upon our ability to identify, develop and commercialize products based on our cell-free protein synthesis platform. In addition to our PCV franchise, our pipeline includes preclinicalVAX-A1, a clinical vaccine candidates VAX-A1candidate for Group A Streptococcus (“Group A Strep”), and VAX-GIVAX-GI, a preclinical vaccine candidate for dysentery and shigellosis. Our research programs may fail to identify potential vaccine candidates for clinical development for a number of reasons or we may focus our efforts and resources on potential programs or vaccine candidates that ultimately prove to be successful in a smaller subset of patients than expected or completely unsuccessful. In addition, we cannot provide any assurance that we will be able to successfully advance any of our existing or future vaccine candidates through the development process.

We expect to continue to rely on third-party manufacturers and suppliers if we receive regulatory approval for any PCV or any other vaccine candidates. For example, in October 2023, we entered into a pre-commercial services and commercial manufacturing supply agreement (the “Lonza Commercial Manufacturing and Supply Agreement”) with Lonza, pursuant to which Lonza will (i) constructconstructed and buildbuilt out a dedicated suite (“Suite”) at Lonza’s facilities in Visp, Switzerland to manufacture certain key components (including drug substance) for our proprietary PCV franchise and any other products or intermediates we may choose (collectively, the “Products”), and (ii) will maintain and operate the Suite (utilizing Lonza’s employees) to manufacture the Products as a service provided to us, including conducting related quality control and quality assurance operations. In September 2025, we also entered into a master services agreement with Patheon Manufacturing Services LLC, part of Thermo Fisher Scientific (collectively, “Thermo Fisher”), pursuant to which Thermo Fisher will commercially manufacture and supply drug product for our PCV candidates, if approved (the “Thermo Fisher Commercial Manufacturing and Supply Agreement”).

We currently have noonly recently begun to build our marketing and sales organization, and as an organization we have nonever experiencemarketed in marketingany products. If we are unable to further establish marketing and sales capabilities or enter into agreements with third parties to market and sell our vaccine candidates, we may not be able to generate product revenue.

We currently have noonly recently begun to build our sales, marketing orand distribution capabilitiesorganization and, as a company, have never marketed any products. Although we have begun hiring sales and asmarketing anpersonnel, we have not yet established a fully developed organization have no experience in marketingthese products.areas. IfContinuing weto develop anthese in-house marketing organization and sales force, wecapabilities will require significant expenses, management resources and time, and we will have to compete with other pharmaceutical and biotechnology companies to recruit, hire, train and retain marketing and sales personnel.

If we are unable or decide not to further establish internal sales, marketing and distribution capabilities, we will pursue collaborative arrangements regarding the sales and marketing of our products; however, there can be no assurance that we will be able to establish or maintain such collaborative arrangements, or if we are able to do so, that they will have effective sales forces. Any revenue we receive will depend upon the efforts of such third parties, which may not be successful. We may have little or no control over the marketing and sales efforts of such third parties and our revenue from product sales may be lower than if we had commercialized our vaccine candidates ourselves. We also face competition in our search for third parties to assist us with the sales and marketing efforts of our vaccine candidates.

There can be no assurance that we will be able to further develop in-house sales and distribution capabilities or establish or maintain relationships with third-party collaborators to commercialize any product that receives regulatory approval in the United States or overseas. If we are unable to further develop in-house sales and distribution capabilities or enter into relationships with third-party collaborators on acceptable terms or at all, we may not be able to successfully commercialize our products. If we are not successful in commercializing our products or any future products, either on our own or through arrangements with one or more third parties, we may not be able to generate any future product revenue and we would incur significant additional losses.

While we have implemented security measures designed to protect against cybersecurity incidents, there can be no assurance that these measures will be effective. We take steps designed to detect, mitigate, and remediate vulnerabilities in our information systems (such as our hardware and/or software, including that of third parties upon which we rely). We may not, however, be able to detect and remediate all such vulnerabilities, including on a timely basis. Despite our efforts to identify and remediate vulnerabilities, if any, in our information technology systems, our efforts may not be successful. Further, we may experience delays in developing and deploying remedial measures designed to address any such identified vulnerabilities. Vulnerabilities could be exploited and result in a cybersecurity incident.

We do not have the infrastructure or capability internally to manufacture supplies for our vaccine candidates or the materials necessary to produce our vaccine candidates for use in the conduct of our preclinical studies or clinical trials, and we lack the internal resources and the capability to manufacture any of our vaccine candidates on a preclinical, clinical or commercial scale. Pursuant to the Manufacturing Rights Agreement with Sutro Biopharma, we obtained exclusive rights to independently, or through certain third parties, develop, improve and manufacture cell-free extract for use in connection with our vaccine candidates. We have engaged Lonza to perform manufacturing process development and clinical manufacture and supply of components for our PCV candidates. Lonza is currently in the process of manufacturing certain components of our vaccine candidates on a clinical scale. In addition, we entered into the Lonza Commercial Manufacturing and Supply Agreement pursuant to which Lonza will (i) constructconstructed and buildbuilt out a Suite at Lonza’s facilities in Visp, Switzerland to manufacture the Products, and (ii) will maintain and operate the Suite (utilizing Lonza’s employees) to manufacture the Products as a service provided to us. In September 2025, we also entered into the Thermo Fisher Commercial Manufacturing and Supply Agreement, pursuant to which Thermo Fisher will commercially manufacture and supply drug product for our PCV candidates, if approved.

▪VAX-31 is a 31-valent, broad-spectrum, carrier-sparing investigational PCV being developed for the prevention of IPD and pneumonia. VAX-31 is the broadest-spectrum PCV in the clinic, and has the potential to provide protection against both currently circulating and historically prevalent serotypes. VAX-31 was designed to increase coverage, in a single vaccine, to approximately 95% of IPD and approximately 88% of pneumococcal pneumonia circulating in adults in the United States aged 50 and older, with the potential to provide an incremental 14-34%13-36% ofbroader coverage for IPD and an incremental 19-31% ofbroader coverage for pneumococcal pneumonia over current standard-of-care adult PCVs.

•In December 2025, following an FDA End-of-Phase 2 meeting, we announced that the first participants were dosed in a Phase 3 pivotal, non-inferiority trial ("OPUS-1") evaluating the safety, tolerability and immune responses of VAX-31 in healthy, pneumococcal-naïve (defined as having no known prior history of IPD or pneumococcal pneumonia, or receipt of any licensed or investigational pnemococcalpneumococcal vaccine) adults aged 50 and older through direct, head-to-head comparisons with both PVC20 and PCV21, the current standard-of-care PCVs. In March 2026, we announced that we completed enrollment of this trial. We expect to announce topline safety, tolerability and immunogenicity data from this study in the fourth quarter of 2026.

•In January 2026, we announced the initiation of an additional Phase 3 trial evaluating VAX-31 when administered concomitantly with a licensed, high-dose seasonal influenza vaccine in pneumococcal-naïve adults aged 50 years and older (“OPUS-2”). In February 2026, we announced the initiation of a separate Phase 3 study evaluating VAX-31 in adults previously vaccinated with a lower-valency pneumococcal vaccine (“OPUS-3”). In March 2026, we announced we completed enrollment of the OPUS-2 trial and in May 2026, we announced we completed enrollment of the OPUS-3 trial. We expect to report safety, tolerability and immunogenicity data from the OPUS-2 and OPUS-3 studies in the first half of 2027. We are also planning for a manufacturing consistency study (e.g., a lot-to-lot study) as the final Phase 3 study to enable the submission of the Biologics License Application (BLA).

•VAX-A1, a novel conjugate vaccine candidate designed to prevent disease caused by Group A Streptococcus (Streptococcus pyogenes) (“Group A Strep”). Group A Strep is pervasive globally and causes an estimated 800 million cases of illness annually, including pharyngitis, or strep throat, and certain severe invasive infections and sequelae. There is currently no vaccine against Group A Strep, which is one of the leading infectious disease-related causes of death and disability worldwide and a significant contributor to the prescription of antibiotics in children. We believe we have demonstrated preclinical proof of concept for VAX-A1, the data for which were published in December 2020. WeIn planJune to2026, initiatewe initiated a Phase 1 adult study for VAX-A1 in mid-2026,VAX-A1, with the primary objective of assessing safety and tolerability, along with a secondary objective of evaluating initial immunogenicity data, to support potential further advancement. We expect to report topline data from this study in the second half of 2027.

Since JanuaryMarch 1,31, 2026, key developments affecting our business include the following:

•AdvancingInitiated Phase 1 Study Evaluating VAX-A1, a Potential Best-in-Class Vaccine Candidate Designed to Provide UniversalBroad Protection Against Disease Caused by Group A Strep, into the ClinicStreptococcus: In FebruaryJune 2026, we announced plans to advancethat the clinicalfirst developmentparticipant ofwas ourdosed mostin advancedthe preclinicalPhase program,1, first-in-human study evaluating VAX-A1, aan investigational prophylactic vaccine candidate designed to prevent disease caused by Group A Strep, with the primary objective of assessing safety and tolerability, along with a secondary objective of evaluating initial immunogenicity data, to support potential further advancement. All participants enrolled in Stage 1 of the study have received the first of two planned doses. The Stage 2 portion of the study is expected to proceed contingent upon the Data Safety Monitoring Board's approval following the review of unblinded Stage 1 safety and tolerability data. All participants in the study will be evaluated for safety through six months after receiving the second dose. Group A Strep remains a major global cause of morbidity and mortality in adults and children and is a leading driver of antibiotic use, underscoring the significant public health burden. We expect to initiate a Phase 1 adult study in mid-2026.burden.'

We have incurred net losses in each year since inception and expect to continue to incur net losses in the foreseeable future. Our net losses may fluctuate significantly from quarter-to-quarter and year-to-year, depending in large part on the timing of our clinical trials and manufacturing activities, and our expenditures on other research and development activities. Our net loss was $320.6$284.3 million and $604.9 million for the three monthsand six months, respectively, ended MarchJune 31,30, 2026. As of MarchJune 31,30, 2026, we had an accumulated deficit of $2.5$2.8 billion and cash, cash equivalents and investments of $2.7$2.5 billion. We believe our cash, cash equivalents and investments will be sufficient to fund our operating expenses and capital expenditure requirements through at least 12 months from the filing date of this Quarterly Report on Form 10-Q.

We do not expect to generate any revenue from commercial product sales unless and until we successfully complete development and obtain regulatory approval for one or more of our vaccine candidates, which we expect will take a number of years. We expect our expenses will increase substantially in connection with our ongoing activities, as we:

Pursuant to the Lonza Commercial Manufacturing and Supply Agreement, Lonza will (i) constructconstructed and buildbuilt out a dedicated suite (the “Suite”) at Lonza’s facilities in Visp, Switzerland to manufacture certain key components (including drug substance) for our proprietary PCV franchise and any other products or intermediates we may choose (collectively, the “Products”). Following completion of construction and (ii)certification of the Suite for commercial operation, the Suite was handed over to the Lonza operations team on August 1, 2026, and Lonza will now maintain and operate the Suite (utilizing Lonza’s employees) to manufacture the Products as a service provided to us, including conducting related quality control and quality assurance operations. Lonza will beis a preferred, non-exclusive, supplier of the Products to us, and we retain the right to procure the Products from one or more alternate and/or backup manufacturers of the Products (including at our own facilities).

Under the Lonza Commercial Manufacturing and Supply Agreement, prior to completion of construction and certification of the Suite for commercial operation, we will contributecontributed to the capital expenditure costs to construct the Suite (and will own certain equipment in the Suite tothat bewas purchased or otherwise acquired by us), and will paypaid Lonza a fixed-rate monthly service fee for Lonza’s pre-commercial services prior to commencement of commercial operationsoperations. (which monthly service fee amount is subject to increases in subsequent years). Following commencement of commercial operations of the Suite to manufacture the Products, weWe will now pay Lonza (i) Suite fees based on allocations of certain of Lonza’s costs to maintain the facility in which the Suite is located and to provide shared services to us and Lonza’s other customers in such facility, (ii) service fees based upon Lonza’s actual full-time equivalent employee (“FTE”) costs to operate the Suite to manufacture the Products, and (iii) equipment expenditures and certain other pass-through costs, including for raw materials. In addition, we may be obligated to pay or reimburse Lonza for certain other fees and expenses under the Lonza Commercial Manufacturing and Supply Agreement. Lonza will be eligible for certain financial bonuses, and subject to certain financial penalties, as incentives for the timely completion of certain scale-up activities, receipt of certain regulatory approvals for the Suite and manufacture of the Products in accordance with our commercial requirements.

Our PCV programs include VAX-31, VAX-24 and VAX-XL, and our non-PCV programs include VAX-A1, VAX-GI, and other discovery-stage programs. In August 2025, we announced that we paused the advancement, beyond preclinical development, of VAX-A1 and VAX-GI while remaining confident in their potential and preserving the option to advance the programs in the future. WeIn nowJune plan2026, towe initiateinitiated a Phase 1 adult study for VAX-A1 in mid-2026.VAX-A1. The majority of our external costs relate to our PCV programs compared to the costs related to non-PCV programs. Most of the external costs associated with our vaccine candidates, particularly our PCV programs, are common in nature, and can be deployed across multiple candidates or redeployed as our vaccine development strategy evolves; as a result, we do not track external costs by candidate, program or project. We do not allocate internal personnel-related costs by program or project because several of our departments support multiple vaccine candidate programs and the hours are not tracked separately by program.

Our vaccine development program for VAX-GI, a novel preclinical vaccine candidate being developed as a preventative treatment for dysentery and shigellosis, which is caused by Shigella bacteria, is currently funded in part by two grants obtained from the NIH administered by the University of Maryland, Baltimore. Our first grant from the NIH was awarded in April 2021 and provides for potential funding up to five years totaling approximately $0.5 million. In June 2023, we received another grant from the NIH that provides for potential funding up to five years totaling approximately $4.6 million. As of MarchJune 31,30, 2026, we have received and expect to continue to receive funding under each of these grants.

We are currently working on a discovery program with the University of North Carolina at Chapel Hill and the University of Chicago to develop a vaccine candidate for the prevention of Chlamydia, which is funded in part by a grant from the NIAID that provides potential funding up to five years totaling approximately $9.5 million. As of MarchJune 31,30, 2026, we have received and expect to continue to receive funding under this grant.

Income from grants is recognized in the period during which the related specified expenses are incurred, provided that the conditions under which the grants were provided have been met. The amount of grant income was not material during the three and six months ended MarchJune 31,30, 2026 and MarchJune 31,30, 2025. Grant income is included as a component of Other income, net in the condensed consolidated statements of operations.

Comparison of the Three and Six Months Ended MarchJune 31,30, 2026 and 2025

Research and development expenses increased by $164.6$73.7 million, or 111.1%,37.9%, during the three months ended MarchJune 31,30, 20262026, compared to the corresponding period in 2025. The increase was largely driven by external costs, which grew by $152.6$64.1 million largelyprimarily due to increased developmentactivities related to clinical trials and product manufacturing activities in connection with our PCV programs. Clinical trials-related expenses increased by $25.4 million primarily due to the activities associated with the VAX-31 OPUS-1, OPUS-2, and OPUS-3 Phase 3 studies. Product manufacturing costs increased by $101.8$23.2 million,million primarily driven by an increase inincreased manufacturing activities, includingactivities to support the potential future commercial launches,launches. clinical trials-relatedResearch expenses increased by $45.0$13.3 million, primarily due to the initiation of and enrollment in the VAX-31 OPUS-1, OPUS-2 and OPUS-3 Phase 3 studies, facility and other allocatedexternal costs increased by $3.9 million, and research expenses increased by $1.3$1.9 million compared to the corresponding period in 2025. The increase was further driven by internal personnel-related costs, which grew by $12.0$9.6 millionmillion, largelyprimarily due to headcount growth.

General and administrative expenses increased by $0.4$2.9 million, or 1.3%, and remained relatively flat9.0% during the three months ended MarchJune 31,30, 2026 compared to the corresponding period in 2025.2025, which was driven primarily by an increase in internal personnel-related costs due to headcount growth.

Other income, net decreased by $14.8$41.2 million, or 37.0%,69.0%, during the three months ended MarchJune 31,30, 2026 compared to the corresponding period in 2025. The decrease was primarily attributable to a $9.4$35.9 million reduction in unrealized and realized foreign currency gains due to fluctuations in the foreign currency exchange rates and a $6.3$5.3 million decrease in interest income as a result of lower cash and investment balances and lower interest rates during the period.

From inception through MarchJune 31,30, 2026, we have incurred losses and negative cash flows from operations and have funded our operations primarily through the issuance of common stock, pre-funded warrants to purchase our common stock and, prior to our IPO, redeemable convertible preferred stock, totaling approximately $5.3 billion in aggregate gross proceeds and $5.1 billion net of underwriting discounts, commissions and offering expenses. As of MarchJune 31,30, 2026, we had $0.3$0.2 billion in cash and cash equivalents, $2.5$2.3 billion in investments and an accumulated deficit of $2.5$2.8 billion.

On February 24, 2026, we entered into a Sales Agreement (the "2026 ATM Sales Agreement") with Leerink Partners LLC ("Leerink Partners"), to issue and sell, from time to time at our discretion, shares of our common stock at an aggregate offering price up to $500.0 million through Leerink Partners as our sales agent. We will pay Leerink Partners a commission of up to 3.0% of the gross sales proceeds of any common stock sold through Leerink Partners under the 2026 ATM Sales Agreement; however, we are not obligated to make any sales of common stock. As of MarchJune 31,30, 2026, we have not sold any shares of our common stock under the 2026 ATM Sales Agreement.

During the three and six months ended MarchJune 31,30, 2025, 3,500,000640,705 and 4,140,705 shares underlying the pre-funded warrants were exercisedexercised, respectively, to receive 3,499,959640,685 and 4,140,644 shares of common stock, respectively, net of exercise costs. No shares underlying the pre-funded warrants were exercised during the three and six months ended MarchJune 31,30, 2026. As of both MarchJune 31,30, 2026 and December 31, 2025, a total of 5,463,793 shares underlying pre-funded warrants were outstanding.

Net cash used in operating activities for the threesix months ended MarchJune 31,30, 2026 was $280.6$513.1 million, an increase of $114.4$225.7 million compared to the threesix months ended MarchJune 31,30, 2025. The increase was primarily due to higher cash expenditures to support our business growth, including increased development and manufacturing activities in connection with the adult and infant PCV programs to support the potential future commercial launches, as well as timing of payments.

Net cash used in investing activities for the threesix months ended MarchJune 31,30, 2026 was $233.4$85.7 million, an increase of $356.7$286.8 million compared to net cash provided by investing activities for the threesix months ended MarchJune 31,30, 2025. The change was primarily attributable to a $269.6$189.3 million increase in purchases of investments and a $99.0$114.6 million decrease in maturities and sales of investments, which were partially offset by a $12.0 million decrease in purchases of property and equipment, manufacturing facility build-out and equipment construction-in-progress.investments.

Net cash provided by financing activities for the threesix months ended MarchJune 31,30, 2026 was $601.6$607.3 million, an increase of $600.8$604.0 million compared to the threesix months ended MarchJune 31,30, 2025. The increase was primarily due to the proceeds of $601.8 million,million in net of issuance costs,proceeds from the follow-on offering during the threesix months ended MarchJune 31,30, 2026, whereas no such offerings occurred during the threesix months ended MarchJune 31,30, 2025.

We have operating lease agreements for our office spaces. As of MarchJune 31,30, 2026, we had total lease payment obligations of $161.0$158.2 million, of which $12.8$13.7 million is payable within one year.

We have certain payment obligations under various license agreements. Under these agreements, we are required to make milestone payments upon successful completion and achievement of certain intellectual property, clinical, regulatory and sales milestones. The payment obligations under the license agreements are contingent upon future events such as our achievement of specified development, clinical, regulatory and commercial milestones, and we will be required to make development milestone payments and royalty payments in connection with the sale of products developed under these agreements. As the achievement and timing of these future milestone payments are not probable or estimable, such amounts have not been included in our condensed consolidated balance sheets as of MarchJune 31,30, 2026 or December 31, 2025.

We enter into agreements in the normal course of business with CMOs and other vendors for manufacturing services and raw materials purchases. We rely on several third-party manufacturers for our manufacturing requirements. As of MarchJune 31,30, 2026, we had the following amounts of non-cancelable purchase commitments related to manufacturing services and raw materials purchased due to our key manufacturing partners. These amounts represent our minimum contractual obligations, including termination fees. If we terminate certain firm orders with our key manufacturing partners, we will be required to pay for the manufacturing services scheduled or raw materials purchased under our arrangements. The actual amounts we pay in the future to the vendors under such agreements may differ from the purchase order amounts.