Slides
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Corporate Presentation November 4, 2025
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2 Forward-Looking Statements November 4, 2025 This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These statements include, but are not limited to, statements related to the potential benefits of Vaxcyte’s carrier-sparing platform and vaccine candidates, including breadth of coverage and the ability to deliver potentially better immune responses, a potentially best-in-class pneumococcal conjugate vaccine (PCV) franchise and the improvement upon the standard- of-care; demand for Vaxcyte’s vaccine candidates; the design, timing of initiation, progress and expected results of Vaxcyte’s preclinical studies, clinical trials and research and development plans (including, but not limited to, the design of the VAX-31 infant Phase 2 study and the timing of the data readout(s) from such study; and the timing of the initiation and data readouts for the VAX-31 adult studies); the ability of Vaxcyte’s cell-free platform to deliver the broadest-spectrum PCVs that provide protection against both currently circulating and historically prevalent strains; applicability of precedent criteria for licensure; Vaxcyte’s ability to establish global commercial manufacturing capacity for its PCV candidates; the ability of Vaxcyte to commercialize its PCV candidates and to meet the PCV franchise market demand for commercial markets; the use and availability of funds from NIH; the growth and expansion of the pneumococcal vaccine market, and the potential to address the need for broader-spectrum of coverage in such market; the market opportunity for Vaxcyte’s vaccines; Vaxcyte’s expectations regarding the potential benefits, spectrum coverage, clinical or regulatory pathways, adoption speed and immunogenicity of its vaccine candidates and other statements that are not historical fact. The words “anticipate,” “believe,” “continue,” “could,” “designed,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “will,” “would” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. These forward-looking statements are based on Vaxcyte’s current expectations and actual results and timing of events could differ materially from those anticipated in such forward-looking statements as a result of risks and uncertainties, including, without limitation, risks related to Vaxcyte’s product development programs, including development timelines, success and timing of chemistry, manufacturing and controls and related manufacturing activities; potential delays or inability to obtain and maintain required regulatory approvals for its vaccine candidates; the risks and uncertainties inherent with preclinical and clinical development processes; the success, cost and timing of all development activities and clinical trials; and sufficiency of cash and other funding to support Vaxcyte’s development programs and other operating expenses. These and other risks are described more fully in Vaxcyte’s filings with the Securities and Exchange Commission (SEC), including its Quarterly Report on Form 10-Q filed with the SEC on November 4, 2025 or in other documents Vaxcyte subsequently files with or furnishes to the SEC. Vaxcyte undertakes no duty or obligation to update any forward-looking statements contained in this release as a result of new information, future events or changes in its expectations.
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November 4, 2025 3 VAXCYTE MISSION STATEMENT We are on a global mission to engineer high- fidelity vaccines that protect humankind from the consequences of bacterial diseases.
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Positive VAX-31 and VAX-24 Study Results Validate Potential of Site-Specific, Carrier-Sparing Platform Highlights: Potential Best-in-Class Pneumococcal Conjugate Vaccine (PCV) Franchise 4IPD = Invasive Pneumococcal Disease, ST= serotype, MOA = Mechanism of Action. • Strategic Manufacturing Approach – Building out capacity to satisfy global PCV demand for commercial markets – Global commercial manufacturing agreement with Lonza to produce PCV key components – Agreement with Thermo Fisher Scientific to establish U.S. fill-finish manufacturing; expands domestic capacity to support future commercial manufacturing – Seasoned management team, directors and advisors • ~$2.7 billion in cash, cash equivalents and investments as of 9/30/25 ALIGNED CRITICAL RESOURCES • Well-defined ~$8B market segment poised for substantial growth – Age range in U.S. expanded to include adults ≥ 50 years of age; and – Developed countries adopting or expanding universal vaccination of adults • Leverages established surrogate immune endpoints as basis for full approval, negating need for field efficacy studies • Serotype and disease spectrum of coverage is the primary adoption driver, yet incumbents limited by carrier suppression HIGHLY ATTRACTIVE PCV MARKET • Scalable, site-specific platform enabling broader-spectrum carrier-sparing PCVs • Adult Indication – VAX-31: Advancing to Phase 3 with initiation of pivotal, non-inferiority study expected in December 20251; received FDA Breakthrough Therapy designation for IPD and pneumonia – Broadest-spectrum PCV in clinic; designed to cover ~95% of IPD, including currently circulating and historically prevalent strains, in U.S. adults aged 50 and older • Pediatric Indication: – VAX-24: Announced final data from positive infant Phase 2 dose-finding study – VAX-31: Ongoing Phase 2 randomized, dose- finding study modified to add VAX-31 Optimized Dose; currently in third and final stage • VAX-XL: Third-generation PCV designed to further expand coverage POTENTIAL BEST-IN-CLASS PCV FRANCHISE • Vaxcyte PCV Franchise – Leverages site-specific conjugation to expose protective T- and B-cell antigens – Enables carrier-sparing conjugates that honor well-understood PCV MOA • Permits production of “tough-to- make” antigens • Platform unlocks large market opportunities – VAX-A1: Novel Group A Strep vaccine – VAX-GI: Novel Shigella vaccine EXCLUSIVE CELL-FREE PLATFORM November 4, 2025 (1) Guidance as of November 4, 2025.
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Harp Dhaliwal, MBA Chief Technology Officer Mike Mullette, MBA Chief Commercial Officer 5 Grant Pickering, MBA Chief Executive Officer & Co-Founder Jim Wassil, MS, MBA Executive VP & Chief Operating Officer November 4, 2025 Experienced Management Team with Track Record in Vaccines and Biopharma Andrew Guggenhime, MBA President & Chief Financial Officer Roger Nosal Head of Global Regulatory & Quality Jeff Fairman, PhD VP Research & Co-Founder Chris Griffith, MS, MBA Chief Business & Strategy Officer
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SPEED, FLEXIBILITY , SCALABILITY • Rapidly screen vaccine candidates • Flexible reaction conditions • Scaled to 1000L using standard equipment SUPERIOR CONJUGATE VACCINES • Site-specifically attach antigens onto protein carriers designed to: – Enable consistent exposure of T-cell epitopes and/or B-cell epitopes on protein carrier – Avoid off-target effects – Enable use of less protein carrier without sacrificing immunogenicity – Enable broader- spectrum vaccines NOVEL PROTEIN VACCINES • Able to produce “tough-to-make” protein antigens that conform to target pathogens • Increased likelihood of protective immune response 6 CELL-FREE PROTEIN SYNTHESIS • Transcriptional & translational (ribosomal) machinery from E. coli stored as a frozen “extract” • Produces singular protein of interest at high yields • Enables site-specific conjugation via insertion of multiple nnAA conjugation anchors • Permits protein production in non- physiological conditions Design and Produce Proteins Beyond Reach of Conventional Methods Cell-Free Protein Synthesis Platform Unlocks Multiple Vaccine Applications November 4, 2025
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7 Broad-Spectrum Conjugate and Novel Protein Vaccines to Prevent Bacterial Infectious Diseases Pipeline of High-Fidelity Vaccines November 4, 2025 Preclinical Phase 1 Phase 2 Phase 3 VAX-A1Novel Group A Strep Vaccine¹ Adults & Infants VAX-2424-Valent PCV Candidate Infants VAX-GI Adults & InfantsNovel Shigella Vaccine¹ VAX-3131-Valent PCV Candidate Adults 50+ Infants Third-Generation PCV Candidate VAX-XL Adults & Infants Approved (1) Paused advancement beyond preclinical development.
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Potential Best-in-Class PCV Franchise for Adult and Infant Segments 8November 4, 2025 Infants 31-valent PCV candidate VAX-31 Adults • Initiate the Phase 3 pivotal, non-inferiority study in December 2025 and announce topline data in 2026 • Initiate remaining Phase 3 studies in 2026 and announce data from these studies in 2027 Population Investigational PCV Key Anticipated Milestones¹ 31-valent PCV candidate VAX-31 • Announce topline data from the ongoing Phase 2 dose- finding study from both the primary immunization series and the booster dose either sequentially or together by the end of first half of 2027 Clinical Development Next Steps and Anticipated Milestones (1) Guidance as of November 4, 2025.
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PCV Opportunity November 4, 2025 9
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A November 4, 2025 10 Streptococcus pneumoniae is the most common pathogen causing pneumococcal disease (PD) • Non-invasive PD includes otitis media, sinusitis, pneumonia • Invasive PD (IPD) includes bacteremia, meningitis • Pneumococci cause over 50% of bacterial meningitis cases in the U.S. Global Health Impact of Pneumococcal Disease Remains Significant Global incidence driven by emerging serotypes not covered by currently available vaccines • In the U.S. alone, over 150K hospitalizations occur annually3 • Streptococcus pneumoniae is the leading cause of vaccine-preventable deaths globally in children under five4 • ~300K children under five years old die annually worldwide due to Streptococcus pneumoniae5 Vaccinations are recommended globally for infants and adults to prevent PD1,2 Routine SOC schedule in the U.S.: • Infants: – Prevnar 20® (PCV20) x 4 doses; or – Vaxneuvance® (PCV15) x 4 doses • Adults aged 50 and older (single dose): – PCV20 or CapvaxiveTM (PCV21); or – PCV15 & Pneumovax® 23 (PPV23) ABOUT STREPTOCOCCUS PNEUMONIAE GLOBAL INCIDENCE & IMPACT OF PD STILL SUBSTANTIAL CURRENT ~$8 BILLION GLOBAL VACCINE CATEGORY (1) https://www.cdc.gov/pneumococcal/hcp/vaccine-recommendations/, (2) https://www.cdc.gov/pinkbook/hcp/table-of-contents/chapter-17-pneumococcal-disease.html. (3) GBD 2019 Diseases and Injuries Collaborators.. Lancet 2020; 396: 1204-22. Supplementary Appendix 2. (4) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8677503/table/T2/, https://www.cdc.gov/pneumococcal/php/surveillance/index.html#:~:text=Global%20trends,deaths%20occur%20in%20developing%20countries.
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November 4, 2025 11 ACIP Recommendations Reinforce Need for Broader-Spectrum PCVs Infant Routine Use Ages 2 – 23 months Children Catch-Up Ages 2 – 6 years Risk Conditions1 Ages 6 – 49 years Adult Routine Use Ages 50+ years Adult Catch-Up2 Ages 65+ years Advisory Committee on Immunization Practices (ACIP) Pneumococcal Vaccine Recommendations PREVNAR 20 (PCV20) VAXNEUVANCE (PCV15) Infant Routine Use Ages 2 – 23 months Children Catch-Up Ages 2 – 6 years Risk Conditions1 Ages 6 – 49 years Adult Routine Use Ages 50+ years PLUS PNEUMOVAX 23 (PPSV23) (1) No prior vaccination with PCV13, PCV15 or PCV20. (2) Shared clinical decision-making is recommended regarding use of a supplemental PCV21 or PCV20 dose for adults aged ≥65 years who have completed their recommended vaccine series with both PCV13 and PPSV23. Sources: 1. https://stacks.cdc.gov/view/cdc/133252, 2.https://www.cdc.gov/pneumococcal/hcp/vaccinerecommendations/index.html?CDC_AA_refVal=https%3A%2F%2Fwww.cdc.gov%2Fvaccines%2Fvpd%2Fpneumo%2Fhcp%2Frecommendations.htm, (3) https://www.cdc.gov/pneumococcal/hcp/vaccine-recommendations/, 4. https://www.cdc.gov/mmwr/volumes/72/rr/rr7203a1.htm. Continued Inclusion of PPSV23 Driven by Lack of Broader- Spectrum PCV CAPVAXIVE (PCV21) ADULTS ONLY Risk Conditions1 Ages 19 – 49 years Adult Routine Use Ages 50+ years Adult Catch-Up2 Ages 65+ years
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12 Non-Vaccine Serotypes Increase in Prevalence, as Circulation of Vaccine Serotypes is Eliminated, Resulting in the Need for Broader-Spectrum Vaccines November 4, 2025 Serotype Replacement Drives Need for Broader-Spectrum Vaccines (1) Ladhani et al, Lancet Infect Dis 2018 Apr;18(4):441-45 inclusive of unpublished raw data. UK IPD CASES IN ADULTS > 651 0 5 10 15 20 25 30 2000 2005 2010 2015 Cases Per 100,000 Prevnar 13 Types Non-vaccine Types Residual disease driven by incremental 11 strains over and above PCV13. PCV13 highly effective in prevention of IPD and circulation of included strains.
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PCVs 13 Broad Coverage But Limited Protection in Adults - Not Boostable Pneumococcal capsular polysaccharides (PS) antigens lead to: • Transient Ab responses (IgM) protect against sepsis, but not pneumonia • No T-cell mediated memory responses, thus no boost • Hyporesponsive effect inhibits ability to boost PCVs post-prime Narrow Coverage But Highly Effective in Adults & Infants - Boostable Conjugation of PS to protein carrier leads to: • Enhanced Ab responses (IgG) that protect against pneumonia • T-cell mediated memory to provide boostable, durable protection • Characteristic interstrand crosslinked matrix-like structures November 4, 2025 PCV Efficacy Driven by T-Cell Epitopes on Diphtheria Toxin Protein Carrier – CRM197 1 T-Cell Note: Graphics adapted from Strugnell et al, Understanding Modern Vaccines, Vol 1, Issue 1, 61-88. (1) Protein carrier in Prevnar 20 is a modified form of diphtheria toxin (CRM197). PS-Only Vaccine Independent Dependent PCVs Designed to Overcome the Limitations of Polysaccharide-Only Vaccines
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14November 4, 2025 Coverage Expansion Needed to Address Circulating Disease, but Protein Carrier Backbone Problematic Limitations of Current PCVs Sources: Prevnar 7, Prevnar 13, Prevnar 20, Vaxneuvance and Capvaxive product inserts. LIMITATIONS OF CONVENTIONAL CHEMISTRY • Random conjugation masks on-target T-cell epitopes on the protein carrier • Conventional reductive amination chemistry requires higher amounts of protein carrier than polysaccharide to form stable conjugates • Overabundance of protein carrier exacerbates carrier suppression, due to competition for CD4+ help between disease-specific polysaccharides and non- disease specific protein carrier PROTEIN CARRIER DIVERTS IMMUNE RESPONSE 20 34 30 51 65 16 31 32 46 84 0 10 20 30 40 50 60 70 80 90 Prevnar 7 Prevnar 13 Vaxneuvance Prevnar 20 Capvaxive Protein Carrier (mcg) Discrete Pneumococcal Polysaccharides (ug)
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(1) Immunoglobulin G (IgG) Geometric Mean Concentrations post-dose 4 – Prevnar 20 BLA Clinical Review Memorandum by FDA (STN: 125731/189). April 27, 2023. (2) Prevnar 20 BLA Clinical Review Memorandum. STN: 125731/0 June 8, 2021. OPA = Opsonophagocytic assay. GMR = Geometric Mean Ratio. Diminished immune response to target polysaccharides due to cumulative amount of protein carrier • Expanded spectrum of coverage requires increasing protein carrier burden • Reduced immune responses consistently demonstrated with > spectrum PCVs in both infants and adults November 4, 2025 Coverage Expansion Using Conventional Chemistry Has Led to Carrier-Induced Immune Suppression Limitations of Current PCVs: Adding Conjugates Results in Lower Ab Titers ADULT IMMUNE RESPONSES (OPA): PCV20 VS PCV132 INFANT IMMUNE RESPONSES (IgG): PCV20 VS PCV131 CARRIER SUPPRESSION 15 0.0 0.5 1.0 1.5 23F 19F 19A 18C 14 9V 7F 6B 6A 5 4 3 1 0.0 0.5 1.0 1.5 23F 19F 19A 18C 14 9V 7F 6B 6A 5 4 3 1 GMR GMR
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Vaxcyte’s Carrier-Sparing PCV Franchise has Potential to Address Need for Broader-Spectrum of Coverage in Growing ~$8B Pneumococcal Market 4 6B 9V 14 18C 19F 23F 1 5 7F 3 6A 19A 22F 33F 8 10A 11A 12F 15B/C 2 9N 17F 201 7C 15A 16F 23A 23B 31 35B 24F Source: Prescribing information for Prevnar, Prevnar 13, Prevnar20, Synflorix, Vaxneuvance, Prevnar 20 and Capvaxive. Company filings for Vaxcyte. Capvaxive is approved for use in adults only. (1) The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. Due to the significant structural homology between 20C and 20B, immune responses elicited by 20C have been demonstrated to be highly cross-reactive with 20B. The Company therefore expects to be able to demonstrate coverage for both serotypes, 20B and 20C, in the VAX-31 adult Phase 3 and infant Phase 2 studies. Reference: Yu J, et al.; New pneumococcal serotype 20C is a WciG O- acetyltransferase deficient variant of canonical serotype 20B. Microbiol Spectr 0:e02443-24. VAX-31 VAX-24: Broadest-spectrum profile designed to cover more serotypes than any pediatric pneumococcal vaccine on-market today VAX-31: 31-valent PCV, the broadest-spectrum PCV in the clinic, designed to cover both currently circulating and historically prevalent serotypes 16November 4, 2025 VAX-24
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17November 4, 2025 VAX-31 Designed to Expand Protection with Broadest Disease Coverage in Adults Percentage of IPD and Non-Bacteremic Pneumococcal Pneumonia Covered by PCVs in U.S. Adults IPD1, ≥50 years Pneumococcal Pneumonia2, ≥50 years All estimates assume cross-protection between serotypes 6A and 6C and between 15B and 15C. (1) CDC 2023 Active Bacterial Core (ABC) Surveillance data; IPD cases with missing serotype data were excluded, non-typeable cases were included in the denominator. (2) King LM et al. Pneumococcal Serotype Distribution and Coverage of Existing and Pipeline Pneumococcal Vaccines, The Journal of Infectious Diseases, 2025, jiaf376; https://doi.org/10.1093/infdis/jiaf376; the percentage covered by PCV is based on a weighted average based on inpatient pneumonia cases (50–64 years of age, ≥65 years of age). 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% PCV15 PCV20 PCV21 VAX-31 47% 61% 81% 95% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% PCV15 PCV20 PCV21 VAX-31 88% 44% 57% 69%
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18November 4, 2025 VAX-31 Designed to Expand Protection with Broadest Disease Coverage in Children Percentage of IPD and Pneumococcal Acute Otitis Media (AOM) Covered by PCVs in U.S. Children IPD1, <5 years All estimates assume cross-protection between serotypes 6A and 6C and between 15B and 15C. (1) CDC 2023 Active Bacterial Core (ABC) Surveillance data; IPD cases with missing serotype data were excluded, non-typeable cases were included in the denominator. (2) Estimated pneumococcal AOM coverage in children under 18: King LM et al. Pneumococcal Serotype Distribution and Coverage of Existing and Pipeline Pneumococcal Vaccines, The Journal of Infectious Diseases, 2025, jiaf376; https://doi.org/10.1093/infdis/jiaf376. In children under five, VAX-31 is estimated to address ~93% of AOM: Grant et al, Characterization of Streptococcus pneumoniae isolates obtained from the middle ear fluid of US children, 2011–2021. (3) VAX-31 includes all serotypes covered by VAX-24, plus an additional 7 serotypes; VAX-24 coverage is depicted in light green and covers 72% of IPD cases in children <5 years and 45% of AOM cases in children <18 years. 48% 69% 92% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% VAX-31PCV20PCV15 VAX-24³ 16% 42% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 80% Pneumococcal AOM2, <18 years VAX-31PCV20PCV15 VAX-24³
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19November 4, 2025 VAX-31 and VAX-24 Have the Potential to Become the Broadest-Spectrum PCVs Pneumococcal Vaccine Market is Highly Attractive PCVs ARE BEST-IN-CLASS • Well-understood T-cell dependent MOA tied to co-presentation of disease-specific polysaccharide antigens with T-cell epitopes on protein carrier to drive durable and boostable immune responses • Well-defined clinical development path with surrogate immune endpoints as basis for full approval, negating need for field efficacy trials COVERAGE & RECOMMENDING BODIES DRIVE ADOPTION • Potential for rapid adoption, with spectrum of coverage and ACIP recommendation driving uptake • Examples: • Shingrix® vs Zostavax® • Gardasil® vs Cervarix® • PCV20 vs PCV15 DURABLE REVENUE STREAM • Prevnar Family (PCV7/PCV13/PCV20) & PPSV23 have generated >$100B in revenues • PCV13 and PCV20 had combined annual sales of ~$6.4B in 2024 ATTRACTIVE MARGINS • Pneumococcal vaccines are premium priced in the U.S., delivering highly attractive margins • Broader-spectrum PCVs extend premium price1 • PCV21: $302 (adult) • PCV20: $275 • PCV15: $241 (pediatric) PNEUMOCOCCAL VACCINE MARKET DYNAMICS • Broader-spectrum of serotype and disease coverage drove 98% adoption for PCV20 over PCV15 despite ACIP recommendation of both vaccines MOA = mechanism of action; SOC = standard of care; ACIP = US CDC Advisory Committee on Immunization Practices. (1) Private Sector costs per dose of the Current CDC Vaccine Price List | VFC Program |. (2) FDA safety assessment of PCV20 data presented at February 2024 ACIP meeting. 2% 98% SEROTYPE & DISEASE COVERAGE ADVANTAGE IS PRIMARY DRIVER OF U.S. PCV MARKET ADOPTION PCV15 PCV20 PCV VACCINATION IN ADULTS AGED ≥ 65 JULY 2021 - NOVEMBER 20232
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November 4, 2025 $0 $2 $4 $6 $8 $10 $12 $14 2024A ~$13B ~$8B Pfizer (Prevnar Family – PCV13 & PCV20) Merck (PCV15, PCV21, PPSV23) GSK (Synflorix) Billions Other (1) Sources: Company websites. (2) Global Pneumococcal Vaccine Market (2022-2027), Infogence Global Research. (3) https://www.cdc.gov/pneumococcal/hcp/vaccine-recommendations/,. 1 PCV MARKET KEY GROWTH DRIVERS 2027E 2 Global Pneumococcal Vaccine Market PCV Market Growth Expected to Reach ~$13B by 2027 Driven Primarily by Growth in Adult Market Pneumococcal Vaccine Market Poised for Significant Growth U.S. Market • In October 2024, ACIP expanded U.S. universal adult vaccination by lowering the age to ≥50 years from ≥65, which significantly expands market • Public health experts and advisory committees have indicated strong consideration for a potential future shift to a prime-boost schedule to support effective long-term protection in adults • “At risk” adults aged 19-49 years included in U.S. universal PCV vaccination recommendation Outside U.S. Market • Serotype epidemiology and availability of broader- valency PCVs is leading to additional adult recommendations outside the U.S. 2020
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21November 4, 2025 Expansion of Adult PCV Recommendations in Select Countries Outside U.S. Serotype Epidemiology, Broad-Valency PCVs Driving New Recommendations and Shift from PPSV23 to PCVs Countries¹ Implementing or Updating Universal, Age-Based Adult PCV Recommendations Following Licensure of Broad-Valency PCVs (PCV20, PCV21) PPSV23 = Pneumovax 23. (1) Transition from PPSV23 to PCV-only or newly introduced PCV recommendation: France, Germany, Japan, Netherlands, Spain (regional, Galicia), Switzerland, United Kingdom. FRANCE Recommendation: PCV for Adults ≥65 GERMANY Recommendation: Shift from PPSV23 to PCV for Adults ≥60 SPAIN Recommendation (Regional): Shift from PPSV23 to PCV for Adults ≥65 SWITZERLAND Recommendation: PCV for Adults ≥65 NETHERLANDS Recommendation: Shift from PPSV23 to PCV for Adults ≥60 UNITED KINGDOM Recommendation: Shift from PPV23 to PCV for Adults ≥65 JAPAN Recommendation: Shift from PPSV23 to PCV for Adults ≥65
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Differentiated PCV Franchise: VAX-31 and VAX-24 22November 4, 2025
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23 eCRM: Enhanced Potency Potential • Avoids masking sites on CRM197 carrier responsible for T-cell help • Optimized sites for conjugation using copper-free click chemistry • More consistent antigenic presentation Carrier-Sparing Conjugates • Less protein carrier / conjugate may allow addition of more serotypes while minimizing carrier suppression and maintaining immunogenicity • VAX-31 and VAX-24 conjugates form standard PCV interstrand crosslinked matrices – Perceived as foreign by the host – Allows use of standard critical quality attributes and serological assays November 4, 2025 Cell-Free Platform Enables Precise Conjugation to Enhance Potency of Standard Protein Carrier Vaxcyte’s PCV Franchise Employs Carrier-Sparing Conjugates PRECISE, SITE-SPECIFIC CONJUGATION SITES ON PROPRIETARY eCRM® PROTEIN CARRIER FINAL VAX-31 & VAX-24 CONJUGATES IN CUSTOMARY MATRIX FORM Illustrative nnAA Conjugation Anchors (red) Avoid T-cell Epitope Regions (pink)
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• Where appropriate, we expect to capitalize on the efficiencies of well-established clinical, manufacturing & regulatory precedents by leveraging conventional methods for the development of VAX-31 and VAX-24 • Vaxcyte has leveraged the same animal models utilized in the development of both approved PCVs (Prevnar and Synflorix) November 4, 2025 24 Utilizes Proven Components, Chemistries and Assays to Reduce Risk and Uncertainty Vaxcyte PCV Franchise Design Leverages Many Standard PCV Conventions CDAP / Periodate Activation Pfizer/Merck Methods Amination for Labeling PS Incorporation of Non-natural AAs Site-Specific Click Chemistry Conjugation Vaxcyte CQA Release Assays (Mol Wt, Free PS) Serological Assays (IgG & OPA) Random Lysine Conjugation Novel Enablement: Site-specific conjugation via incorporation of nnAA conjugation anchors Polysaccharide Protein Carrier Assays
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VAX-31 Adult Clinical Program 25November 4, 2025
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Unprecedented Results Support Potential Best-in-Class PCV With Broadest Serotype and Disease Coverage Summary of VAX-31 Adult 50+ Phase 1/2 Study Topline Data Findings 26November 4, 2025 SAFETY AND TOLERABILITY: At all doses studied, VAX-31 was well tolerated and demonstrated a safety profile similar to Prevnar 20® (PCV20) for all doses IMMUNOGENICITY: At all doses studied, VAX-31 demonstrated robust OPA immune responses for all 31 serotypes (STs) – all three doses advanceable to Phase 3 • High and Middle doses met or exceeded OPA regulatory immunogenicity criteria for all 31 STs, Low Dose for 29 of 31 STs • For the 20 STs common with PCV20: High Dose, 18 had GMR greater than 1.0 and 7 achieved statistically higher immune responses; Middle Dose, 13 had GMR greater than 1.0 and 5 achieved statistically higher immune responses; Low Dose, 8 had GMR greater than 1.0 and 3 achieved statistically higher immune responses • For the 11 additional STs unique to VAX-31: All 11 met the superiority criteria at all doses Adult PCV Franchise Strategy: • Adults: VAX-31 High Dose (all serotypes dosed at 3.3mcg or 4.4mcg) selected to advance to Phase 3 PLATFORM: The VAX-31 data further validate the potential of Vaxcyte’s carrier-sparing platform to deliver the broadest-spectrum PCVs that provide protection against both currently circulating and historically prevalent STs GMR = geometric mean ratio; OPA = Opsonophagocytic activity.
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Randomized, Observer-Blind, Dose-Finding, Controlled Study to Evaluate Safety, Tolerability and Immunogenicity of VAX-31 vs Standard-of-Care (PCV20) in 1,015 Healthy Adults ≥ 50 Years Dose Blood Sample PCV20 VAX-31 High Dose VAX-31 Middle Dose VAX-31 Low Dose Safety Follow-Up Randomize (1:1:1:1) Screen DMC Review Final Safety Assessment Dose PCV20 VAX-31 High Dose VAX-31 Middle Dose VAX-31 Low Dose Randomize (1:1:1:1) Screen Final Safety Assessment OPA & IgG VAX-31 vs PCV20 Blood Sample Safety Follow-Up OPA & IgG VAX-31 vs PCV20 Stage 1: Adults 50-64 (n=64) Stage 2: Adults ≥ 50 (n=951) Day 0 Month 1 Month 6Day 8 Day 0 Month 1 Month 6Day 8 Overview of VAX-31 Phase 1/2 Clinical Study Design (N=1,015) 27November 4, 2025 DMC: Data Monitoring Committee, IgG: Immunoglobulin G. In the Low, Middle and High doses, all serotypes were dosed at 1.1mcg, 2.2mcg and 3.3mcg, respectively, except serotypes 1, 5 and 22F, which were dosed at 1.65mcg, 3.3mcg, and 4.4mcg, respectively.
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28November 4, 2025 Middle and High Doses Met OPA Response Non-Inferiority Criteria for All 20 Common STs Compared to PCV20 VAX-31 Induced Robust Immune Responses for All 20 Common STs GMR: 0.0 0.5 1.0 1.5 2.0 2.5 33F 23F 22F 19F 19A 18C 15B 14 12F 11A 10A 9V 8 7F 6B 6A 5 4 3 1 VAX-31 Low Dose 0.0 0.5 1.0 1.5 2.0 2.5 33F 23F 22F 19F 19A 18C 15B 14 12F 11A 10A 9V 8 7F 6B 6A 5 4 3 1 VAX-31 High Dose 0.0 0.5 1.0 1.5 2.0 2.5 33F 23F 22F 19F 19A 18C 15B 14 12F 11A 10A 9V 8 7F 6B 6A 5 4 3 1 VAX-31 Middle Dose * * * * * * * * * * * * * Reached statistical significance for superiority. Low Dose: 8 of 20 STs had a GMR greater than 1.0 and 3 STs achieved statistically higher immune responses Middle Dose: 13 of 20 STs had a GMR greater than 1.0 and 5 STs achieved statistically higher immune responses High Dose: 18 of 20 STs had a GMR greater than 1.0 and 7 STs achieved statistically higher immune responses * * *
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VAX-31 Induced Robust Immune Responses for All 11 Incremental STs All Three Doses Met Superiority Criteria for All Incremental STs Compared to PCV20 29November 4, 2025 2 7C 9N 15A 16F 17F 20B 23A 23B 31 35B 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% VAX-31 Middle Dose % difference with a > 4-fold OPA titer increase (95% CI) 2 7C 9N 15A 16F 17F 20B 23A 23B 31 35B 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% VAX-31 High Dose 2 7C 9N 15A 16F 17F 20B 23A 23B 31 35B 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% VAX-31 Low Dose 1 10 100 35B 31 23B 23A 20B 17F 16F 15A 9N 7C 2 GMR: 1 10 100 35B 31 23B 23A 20B 17F 16F 15A 9N 7C 2 1 10 100 35B 31 23B 23A 20B 17F 16F 15A 9N 7C 2 The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 1 on slide 16.
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30 VAX-31 Full Six-Month Safety Data Similar to PCV20 and Across Cohorts November 4, 2025 VAX-31 Low Dose VAX-31 Middle Dose VAX-31 High Dose PCV20 NUMBER OF SUBJECTS WITH: 255 254 253 253 Unsolicited TEAE, n (%) 42 (16.5) 43 (16.9) 47 (18.6) 42 (16.6) Related Unsolicited TEAE, n (%) 7 (2.7) 11 (4.3) 17 (6.7) 12 (4.7) MAAE, n (%) 45 (17.6) 42 (16.5) 35 (13.8) 31 (12.3) Related MAAE, n (%) 1 (0.4) 4 (1.6) 0 0 NOCI, n (%) 2 (0.8) 6 (2.4) 5 (2.0) 5 (2.0) Related NOCI, n (%) 1 (0.4) 0 0 0 SAE, n (%) 2 (0.8) 3 (1.2) 5 (2.0) 3 (1.2) Related SAE, n (%) 0 0 0 0 Death, n (%) 0 0 0 0 Related Death, n (%) 0 0 0 0 TEAE = Treatment emergent adverse events; MAAE = Medically attended adverse events; NOCI = New onset of chronic illnesses; SAE = Serious adverse events. Excludes Solicited AEs.
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VAX-24 Infant Phase 2 Dose-Finding Study Final Results 31November 4, 2025
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Final VAX-24 Phase 2 Infant Study Results and Platform Demonstrate Potential to Achieve Broadest Coverage of Any Infant PCV On-Market 32November 4, 2025 Overall study results positive and met objectives Safety and tolerability profile similar to standard-of-care VAX-24 elicited substantial IgG, OPA and memory responses and performed particularly well against currently circulating serotypes contained in the vaccine Results consistent with previously reported positive interim results; provide additional evidence validating rationale for exploring higher doses in ongoing VAX-31 infant Phase 2 dose-finding study Substantial, dose-dependent immune responses and little to no evidence of carrier suppression observed
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Stage 1: Dose Escalation (n=48*) Stage 2: Main Study (n=789*) VAX-24 Infant Phase 2 Dose-Finding Clinical Study (N=803) Randomize (3:1) Screen VAX-24 1.1 mcg PCV15 DSMB Dose 1 Safety Review at 7 Days VAX-24 2.2mcg PCV15 DSMB VAX-24 2.2mcg/ 4.4mcg PCV15 DSMB Randomize (1:1:1:1) Screen Age 2 months Dose 1 4 months 6 months 7 months 12-15 months 13-16 months 18-21 months Dose 2 Dose 3 Primary Series Immunogenicity Endpoint Dose 4 Boost Immunogenicity Endpoint PCV20 VAX-24 1.1mcg VAX-24 2.2mcg VAX-24 2.2mcg/4.4mcg Age 2 months Dose 1 Safety Review At 7 Days Dose 1 Safety Review at 7 Days Final Safety Assessment November 4, 2025 Randomized, Observer-Blind, Active-Controlled, Dose-Finding, Clinical Study to Evaluate Safety, Tolerability and Immunogenicity of VAX-24 vs. Standard-of-Care (PCV20) in 803 Healthy Infants (*) The 36 subjects from the three VAX-24 cohorts in Stage 1 proceeded to Stage 2 of the study. The 12 subjects who received PCV15 in Stage 1 were given PCV20 in Stage 2 and followed separately; they are not included in the safety or immunogenicity evaluable populations. Two (2) subjects withdrew after being randomized in Stage 2. All 36 VAX-24 subjects from Stage 1 proceeded to Stage 2 33
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Identical to Doses Evaluated in VAX-24 Adult Program Three VAX-24 Doses Evaluated in Infant Phase 2 Dose-Finding Study November 4, 2025 3 19F 15B2 22F 33F 11A 10A 19A 18C 7F 4 8 6B 12F 9V 14 23F 5 6A 1 9N 20C3 17F 2 4.4 mcg 4.4 mcg 4.4 mcg 4.4 mcg 4.4 mcg 4.4 mcg 4.4 mcg 4.4 mcg Low Dose (1.1mcg) Middle Dose (2.2mcg) Mixed Dose (2.2mcg/ 4.4mcg) PCV20 VAX-24 (2.2mcg) • Mixed dose includes seven serotypes at 4.4mcg strategically chosen based on epidemiological relevance or prior evidence of dose-dependent immune responses to increase the probability of generating non-inferior immune responses for those serotypes. 34 % of IPD in US children <5 yrs of age1 14.5% 13.8% 13.1% 9.7% 6.2% 4.8% 3.5% 1.4% 0.7% 0.7% 0.7% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 1.4% 1.4% 0.0% 0.0% (1) % of IPD caused in individuals <5 yrs of age in the U.S. in 2023 based on ABC surveillance data References: https://data.cdc.gov/Public-Health-Surveillance/1998-2023-Serotype-Data-for-Invasive-Pneumococcal-/qvzb-qs6p/about_data. (2) 15C coverage due to cross protection against 15B. The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 3 on slide 16.
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Study Disposition November 4, 2025 VAX-24 Infant Phase 2 Dose-Finding Study (1) Of the 803 randomized subjects, (i) 14 received PCV15 for dose 1 and are not included in the PCV20 vaccinated population and (ii) 2 withdrew prior to vaccination. (2) The Safety Evaluable Population includes subjects who received the same vaccine across all doses. (3) The IEP3 includes eligible subjects who received the same vaccine across the first 3 doses, with valid PD3 IgG or OPA assay results based on blood sample collected within protocol-defined window, and without protocol deviations that may interfere with PD3 immune response. (4) The IEP4 includes eligible subjects who received the same vaccine across all 4 doses, with valid PD4 IgG or OPA assay results based on blood sample collected within protocol-defined window, and without protocol deviations that may interfere with PD4 immune response. Randomized N = 8031 Included in Safety Evaluable Population2 N = 185 Included in Safety Evaluable Population2 N = 191 Included in Safety Evaluable Population2 N = 186 Included in Safety Evaluable Population2 N = 195 Vaccinated PCV20 N = 187 Vaccinated VAX-24 Low Dose N = 205 Vaccinated VAX-24 Mid Dose N = 201 Vaccinated VAX-24 Mixed Dose N = 194 Included in PD3 Immunogenicity Evaluable Population (IEP33) N = 151 Included in PD4 Immunogenicity Evaluable Population (IEP44) N = 126 Included in PD3 Immunogenicity Evaluable Population (IEP33) N = 153 Included in PD4 Immunogenicity Evaluable Population (IEP44) N = 119 Included in PD3 Immunogenicity Evaluable Population (IEP33) N = 144 Included in PD4 Immunogenicity Evaluable Population (IEP44) N = 125 Included in PD3 Immunogenicity Evaluable Population (IEP33) N = 131 Included in PD4 Immunogenicity Evaluable Population (IEP44) N = 101 35
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Population Demographics Generally Balanced Across Cohorts November 4, 2025 VAX-24 Low Dose VAX-24 Mid Dose VAX-24 Mixed Dose PCV20 NUMBER OF SUBJECTS 205 201 194 187 Median Age, days (Q1, Q3)1 65 (63, 69) 65 (63, 70) 65 (63, 70) 65 (63, 70) Sex, n (%) Female 113 (55.1) 104 (51.7) 93 (47.9) 87 (46.5) Male 92 (44.9) 97 (48.3) 101 (52.1) 100 (53.5) Race, n (%) White 139 (67.8) 141 (70.1) 138 (71.1) 127 (67.9) Black 38 (18.5) 35 (17.4) 29 (14.9) 30 (16.0) Asian 3 (1.5) 0 (0.0) 5 (2.6) 2 (1.1) Native Hawaiian 0 (0.0) 1 (0.5) 0 (0.0) 1 (0.5) American Indian or Native Alaskan 1 (0.5) 1 (0.5) 2 (1.0) 1 (0.5) Other/ Multiracial 24 (11.7) 23 (11.4) 20 (10.3) 26 (13.9) Median Weight, kg (Q1, Q3)1 5.19 (4.81, 5.68) 5.22 (4.74, 5.86) 5.30 (4.89, 5.77) 5.22 (4.77, 5.70) Median Length, cm (Q1, Q3)1 57.79 (55.88, 59.30) 57.79 (55.88, 59.69) 57.90 (55.88, 59.69) 58.17 (55.88, 59.69) Median Gestational Age, weeks (Q1, Q3)1 39 (38, 39) 39 (38, 39) 39 (38, 39) 39 (38, 39) Median Birth Weight, kg (Q1, Q3)1 3.30 (2.95, 3.60) 3.28 (3.01, 3.60) 3.29 (3.00, 3.63) 3.24 (2.98, 3.60) 36(1) Q1 = First Quartile or 25th Percentile. Q3 = Third Quartile or 75th Percentile.
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Study Safety, Tolerability and Immunogenicity Key Outcome Measures SAFETY AND TOLERABILITY OUTCOME MEASURES IMMUNOGENICITY OUTCOME MEASURES DAY 7 AFTER EACH DOSE 1 MONTH POST-DOSE 1-4; ONGOING DURING PRIMARY SERIES • Solicited local reactions • Solicited systemic events • Unsolicited adverse events (AE) • % of subjects achieving Immunoglobulin G (IgG) antibody concentration ≥0.35 mcg/mL (seroconversion rate) • IgG Geometric Mean Concentration (GMC) • Opsonophagocytic activity (OPA) Geometric Mean Titer (GMT) 1 MONTH POST- DOSE 3 (PD3) 1 MONTH POST- DOSE 4 (PD4) • % of subjects achieving IgG antibody concentration ≥0.35 mcg/mL • IgG GMC and IgG GMC ratio (GMR) • OPA GMT • IgG and OPA Geometric Mean Fold Rise (GMFR) from pre- Dose 4 to 1-month PD4 • % of subjects achieving a 4-fold rise in IgG and OPA from pre- Dose 4 to 1-month PD4 6 MONTHS PD4 • Unsolicited AE • SAE, NOCI and MAAE November 4, 2025 • Serious adverse events (SAE), new onset of chronic illnesses (NOCI), medically attended adverse events (MAAE) and treatment emergent AE (TEAE) • SAE, NOCI, MAAE and TEAE 37
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Tolerability and Final 6-Month Safety Data November 4, 2025 38
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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Low Mid Mixed PCV20 Low Mid Mixed PCV20 Low Mid Mixed PCV20 Through 7 Days After Any Dose VAX-24 Well Tolerated Across All Dose Cohorts – Local Solicited AEs November 4, 2025 ErythemaEdema Tenderness at Injection Site Mild Moderate Severe 39
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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% November 4, 2025 . Fever Irritability Decreased Appetite Decreased Sleep Increased Sleep Through 7 Days After Any Dose VAX-24 Well Tolerated Across All Dose Cohorts – Systemic Solicited AEs Mild Moderate Severe 40
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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% PD1 PD2 PD3 PD4 PD1 PD2 PD3 PD4 PD1 PD2 PD3 PD4 PD1 PD2 PD3 PD4 Severe Moderate Mild Through 7 Days After Each of Three Primary Doses and Booster VAX-24 Well Tolerated Across All Dose Cohorts – Any Solicited AE November 4, 2025 VAX-24 MidVAX-24 Low VAX-24 Mixed PCV20 41 PD1 = Post-Dose 1. PD2 = Post-Dose 2. PD3 = Post-Dose 3. PD4 = Post-Dose 4/Booster.
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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Low Mid Mixed PCV20 Low Mid Mixed PCV20 Low Mid Mixed PCV20 Through 7 Days Post-Dose 4 (Booster) VAX-24 Well Tolerated Across All Dose Cohorts – Local Solicited AEs November 4, 2025 ErythemaEdema Tenderness at Injection Site Mild Moderate Severe 42 (None)
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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% November 4, 2025 . Fever Irritability Decreased Appetite Decreased Sleep Increased Sleep Through 7 Days Post-Dose 4 (Booster) VAX-24 Well Tolerated Across All Dose Cohorts – Systemic Solicited AEs Mild Moderate Severe 43
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Final 6-Month Safety Data from VAX-24 Phase 2 Study Safety Results Similar to PCV20 and Across Cohorts November 4, 2025 VAX-24 Low Dose VAX-24 Mid Dose VAX-24 Mixed Dose PCV20 NUMBER OF SUBJECTS 195 186 191 185 Unsolicited TEAE, n (%) 167 (85.6) 161 (86.6) 163 (85.3) 169 (91.4) Related Unsolicited TEAE, n (%) 6 (3.1) 13 (7.0) 13 (6.8) 6 (3.2) MAAE, n (%) 172 (88.2) 155 (83.3) 167 (87.4) 161 (87.0) Related MAAE, n (%) 3 (1.5) 3 (1.6) 3 (1.6) 1 (0.5) NOCI, n (%) 12 (6.2) 12 (6.5) 15 (7.9) 10 (5.4) Related NOCI, n (%) 0 1 (0.5)1 0 0 SAE, n (%) 10 (5.1) 7 (3.8) 11 (5.8) 11 (5.9) Related SAE, n (%) 0 0 0 0 Death, n (%) 0 0 0 1 (0.5)2 Related Death, n (%) 0 0 0 0 TEAE = Treatment emergent adverse events; NOCI = new onset of chronic illnesses; MAAE = medically attended adverse events; SAE = Serious adverse events. (1) Related NOCI = mild nasal congestion. (2) One sudden infant death syndrome (SIDS) case occurred in the PCV20 cohort 7 weeks after the first and only dose was administered; following a thorough investigation, case was found to be unrelated to study vaccine. 44
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Final Immunogenicity Data Results November 4, 2025 45
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Criteria for Infant Phase 2 Immunogenicity Measures to Support Phase 3 Advancement and Precedent FDA Considerations for Broader-Spectrum Infant PCV Licensure November 4, 2025 • For common serotypes (STs): Lower limit (LL) of the 95% CI for the difference between the proportion of participants achieving the seroconversion rate (pre- defined IgG concentration ≥0.35 mcg/mL) is > -15%2 for each ST • For unique STs: Achieve same IgG concentration threshold as above, but compared to the ST with the lowest response rate in the comparator PCV, excluding ST3 Primary Series Non-Inferiority Post-Dose 3 (PD3) or “Prime” • For common STs: IgG GMRs with point estimate of >0.6 for each ST3 • For unique STs: Achieve same IgG GMR threshold as above compared to the ST with lowest IgG GMC in the comparator PCV, excluding ST3 Booster Dose Non-Inferiority Post-Dose 4 (PD4) or “boost” 46 (1) Sources: April 27, 2023 Clinical Review - Prevnar20.pdf and June 17, 2022 Clinical Review (STN 125741/6) – VAXNEUVANCE. (2) Merck applied the >-15% for V114 (Vaxneuvance) Phase 2 endpoint supporting advancement to Phase 3 (https://pmc.ncbi.nlm.nih.gov/articles/PMC7360095/). (3) Based on our statistical analysis of precedent Phase 2 and Phase 3 studies. • IgG antibody levels PD3 (GMR) • Functional antibody levels PD3 and PD4 (OPA) • IgG seroconversion rates PD4 Secondary Immunogenicity Endpoints TOTALITY OF DATA1 Additional Key Considerations • % of circulating disease for each ST • Magnitude of antibody responses • Degree of shortfall on primary endpoints Phase 2 Target • For common STs: FDA has evaluated larger Phase 3 NI registration studies based on achievement of seroconversion rate of > -10% for each ST • For unique STs: Achieve same IgG concentration threshold as above, but compared to the ST with the lowest response rate in the comparator PCV, excluding ST3 • For common STs: FDA has evaluated larger Phase 3 NI registration studies based on LL of the 95% CI for IgG GMR >0.5 for each ST • For unique STs: Achieve same IgG GMR threshold as above compared to the ST with lowest IgG GMC in the comparator PCV, excluding ST3 Phase 3 Endpoints CI = confidence interval; IgG = Immunoglobulin G.
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Post-Dose 3 (PD3) IgG and OPA Immunogenicity Data Results 47November 4, 2025
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VAX-24 Demonstrated High Overall Seroconversion Rates Across All Doses PD3 November 4, 2025 48 Unique SerotypesSerotypes Common with PCV20 VAX-24 Mixed Dose 3 19F 15B 22F 33F 11A 10A 19A 18C 7F 4 8 6B 12F 9V 14 23F 5 6A 1 9N 20C 17F 2 0 20 40 60 80 100 % of subjects with predefined IgG levels (>0.35mcg/mL) VAX-24 Low Dose PCV20 VAX-24 Mid Dose IgG = Immunoglobulin G. 15C coverage due to cross protection against 15B. The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 3 on slide 16. POST-DOSE 3 RESULTS
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November 4, 2025 49 Met Precedent Phase 2 Non-Inferiority Criteria for 20 of 24 STs at Low and Mid Doses and 19 of 24 STs at Mixed Dose VAX-24 PD3 Seroconversion Rates Compared to PCV20 0.7% 0.7% 1.4% 3.5% 4.8% 6.2% 9.7% 13.1% 13.8% 14.5% 0%5%10%15% 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B/C 19F 3 -30 -15 0 15 30 45 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B 19F 3 -30 -15 0 15 30 45 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B 19F 3 -30 -15 0 15 30 45 60 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B 19F 3 VAX-24 vs. PCV20: Difference in % of Subjects Meeting Predefined IgG Levels2 Difference in % of Subjects Meeting Predefined IgG Levels VAX-24 Low Dose (1.1mcg) VAX-24 Mixed Dose (2.2mcg/4.4mcg)VAX-24 Mid Dose (2.2mcg) % of IPD in US children <5 yrs of age1 -30 -15 0 15 30 45 2 17F 20C 9N Difference in % of Subjects Meeting Predefined IgG Levels Difference in % of Subjects Meeting Predefined IgG Levels -30 -15 0 15 30 45 2 17F 20C 9N -30 -15 0 15 30 45 2 17F 20C 9N NI = Non-inferiority; IgG = Immunoglobulin G. Unique STs0.0% 0.0% 1.4% 1.4% 0%5%10%15% 2 17F 20 9N 0.7% 0% 0% 0% 0% 0% 0% 0% 0% 0% (1) % of IPD caused in individuals <5 yrs of age in the U.S. in 2023 based on ABC surveillance data References: https://data.cdc.gov/Public-Health-Surveillance/1998-2023-Serotype-Data-for-Invasive-Pneumococcal-/qvzb-qs6p/about_data. (2) % of subjects meeting ≥0.35mcg/mL for unique STs were calculated compared to ST 6B, which is the ST in PCV20 with the lowest seroconversion rate Post-Dose 3 (excluding ST 3 or lower responding STs). 15C coverage due to cross protection against 15B. The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 3 on slide 16. X = STs dosed at 4.4mcg. POST-DOSE 3 RESULTS = Point Estimate.
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0.0 0.5 1.0 1.5 2.0 2.5 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B 19F 3 November 4, 2025 50 Met Target Phase 2 Non-Inferiority Criteria for Point Estimate of >0.6 on 21 of 24 STs at Mid and Mixed Doses VAX-24 PD3 IgG GMRs Compared to PCV20 IgG Geometric Mean Ratios for VAX-24 vs. PCV202 0 2 4 6 8 10 2 17F 20C 9N 0.0 0.5 1.0 1.5 2.0 2.5 3.0 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B 19F 3 0.0 0.5 1.0 1.5 2.0 2.5 3.0 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B 19F 3 0 2 4 6 8 10 2 17F 20C 9N 0 2 4 6 8 10 2 17F 20C 9N % of IPD in US children <5 yrs of age1 GMR GMR VAX-24 Low Dose (1.1mcg) VAX-24 Mixed Dose (2.2mcg/4.4mcg)VAX-24 Mid Dose (2.2mcg) = Point Estimate. Unique STs0.0% 0.0% 1.4% 1.4% 0%5%10%15% 2 17F 20 9N 0% 0% 0% 0.7% 0.7% 1.4% 3.5% 4.8% 6.2% 9.7% 13.1% 13.8% 14.5% 0%5%10%15% 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B/C 19F 3 0.7% 0% 0% 0% 0% 0% 0% (1) % of IPD caused in individuals <5 yrs of age in the U.S. in 2023 based on ABC surveillance data References: https://data.cdc.gov/Public-Health-Surveillance/1998-2023-Serotype-Data-for-Invasive-Pneumococcal-/qvzb-qs6p/about_data (2) GMRs for unique STs were calculated compared to ST 12F, which is the ST in PCV20 with the lowest GMC Post-Dose 3 (excluding ST 3 or lower responding STs). 15C coverage due to cross protection against 15B. The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 3 on slide 16. X = STs dosed at 4.4mcg. POST-DOSE 3 RESULTS
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November 4, 2025 51 Unique SerotypesSerotypes Common with PCV20 3 19F 15B 22F 33F 11A 10A 19A 18C 7F 4 8 6B 12F 9V 14 23F 5 6A 1 9N 20B 17F 2 1 10 100 1000 10000 100000 OPA GMTs (95% CI) VAX-24 Low Dose PCV 20 VAX-24 Mid Dose VAX-24 Mixed Dose VAX-24 PD3 OPA GMT Immune Responses 15C coverage due to cross protection against 15B. The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 3 on slide 16. Serotype 20B was studied in this OPA analysis. POST-DOSE 3 RESULTS Demonstrated Robust OPA Titers, Generally Consistent with IgG Responses
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Post-Dose 4 (PD4) IgG and OPA Immunogenicity Data Results 52November 4, 2025
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VAX-24 Demonstrated High Overall Seroconversion Rates Across All Doses PD4 November 4, 2025 53 Unique SerotypesSerotypes Common with PCV20 VAX-24 Mixed Dose 3 19F 15B 22F 33F 11A 10A 19A 18C 7F 4 8 6B 12F 9V 14 23F 5 6A 1 9N 20C 17F 2 0 20 40 60 80 100 % of subjects with predefined IgG levels (>0.35mcg/mL) VAX-24 Low Dose PCV20 VAX-24 Mid Dose 15C coverage due to cross protection against 15B. The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 3 on slide 16. IgG = Immunoglobulin G. POST-DOSE 4 RESULTS
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0.0 0.5 1.0 1.5 2.0 2.5 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B 19F 3 November 4, 2025 54 Met Target Ph2 Non-Inferiority Criteria for Point Estimate of >0.6 on 19 of 24 STs at Mixed Dose and 18 of 24 STs at Mid Dose VAX-24 PD4 IgG GMRs Compared to PCV20 IgG Geometric Mean Ratios for VAX-24 vs. PCV202 0 2 4 6 8 10 2 17F 20C 9N 0.0 0.5 1.0 1.5 2.0 2.5 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B 19F 3 0.0 0.5 1.0 1.5 2.0 2.5 3.0 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B 19F 3 0 2 4 6 8 10 2 17F 20C 9N 0 2 4 6 8 10 2 17F 20C 9N % of IPD in US children <5 yrs of age1 GMR GMR VAX-24 Low Dose (1.1mcg) VAX-24 Mixed Dose (2.2mcg/4.4mcg)VAX-24 Mid Dose (2.2mcg) = Point Estimate. Unique STs0.0% 0.0% 1.4% 1.4% 0%5%10%15% 2 17F 20 9N 0% 0% 0% 0.7% 0.7% 1.4% 3.5% 4.8% 6.2% 9.7% 13.1% 13.8% 14.5% 0%5%10%15% 1 6A 5 23F 14 9V 12F 6B 8 4 7F 18C 19A 10A 11A 33F 22F 15B/C 19F 3 0.7% 0% 0% 0% 0% 0% 0% (1) % of IPD caused in individuals <5 yrs of age in the U.S. in 2023 based on ABC surveillance data References: https://data.cdc.gov/Public-Health-Surveillance/1998-2023-Serotype-Data-for-Invasive-Pneumococcal-/qvzb-qs6p/about_data (2) GMRs for unique STs were calculated compared to ST 12F, which is the ST in PCV20 with the lowest GMC Post-Dose 3 (excluding ST 3 or lower responding STs). 15C coverage due to cross protection against 15B. The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 3 on slide 16. X = STs dosed at 4.4mcg. POST-DOSE 4 RESULTS
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November 4, 2025 55 Unique SerotypesSerotypes Common with PCV20 3 19F 15B 22F 33F 11A 10A 19A 18C 7F 4 8 6B 12F 9V 14 23F 5 6A 1 9N 20B 17F 2 1 10 100 1000 10000 100000 OPA GMTs (95% CI) VAX-24 Low Dose PCV 20 VAX-24 Mid Dose VAX-24 Mixed Dose VAX-24 PD4 OPA GMT Immune Responses 15C coverage due to cross protection against 15B. The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 3 on slide 16. Serotype 20B was studied in this OPA analysis. POST-DOSE 4 RESULTS Demonstrated Robust OPA Titers, Generally Consistent with IgG Responses
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November 4, 2025 56 3 19F 15B 22F 33F 11A 10A 19A 18C 7F 4 8 6B 12F 9V 14 23F 5 6A 1 2 9N 17F 20C 0 5 10 15 IgG GMCs mcg/mLs (95% CI) VAX-24 Mid Dose Pre-Dose 4 VAX-24 Mid Dose Post-Dose 4 VAX-24 Demonstrated Robust Memory Responses Pre- vs Post-Dose 4 IgG GMCs Non-PCV20 SerotypesSerotypes Contained in PCV20 15C coverage due to cross protection against 15B. The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 3 on slide 16. IgG = Immunoglobulin G.
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Expanded Analysis with Concomitant Flu Vaccination 57November 4, 2025
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Population: Immunogenicity Evaluable Population (IEP): 153 IEP + Concomitant Flu Vaccine: 162 0.0 0.5 1.0 1.5 2.0 10A - IEP3 + Flu 10A - IEP3 9V - IEP3 + Flu 9V - IEP3 8 - IEP3 + Flu 8 - IEP3 7F - IEP3 + Flu 7F - IEP3 6B - IEP3 + Flu 6B - IEP3 6A - IEP3 + Flu 6A - IEP3 5 - IEP3 + Flu 5 - IEP3 4 - IEP3 + Flu 4 - IEP3 3 - IEP3 + Flu 3 - IEP3 1 - IEP3 + Flu 1 - IEP3 0.0 0.5 1.0 1.5 2.0 33F - IEP3 + Flu 33F - IEP3 23F - IEP3 + Flu 23F - IEP3 22F - IEP3 + Flu 22F - IEP3 19F - IEP3 + Flu 19F - IEP3 19A - IEP3 + Flu 19A - IEP3 18C - IEP3 + Flu 18C - IEP3 15B - IEP3 + Flu 15B - IEP3 14 - IEP3 + Flu 14 - IEP3 12F - IEP3 + Flu 12F - IEP3 11A - IEP3 + Flu 11A - IEP3 November 4, 2025 GMR . 58 Consistently Improved Immunogenicity Responses Evidenced in Mid Dose VAX-24 PD3 IgG GMRs Compared to PCV20 Including Subjects Who Received Flu Vaccination IgG Geometric Mean Ratios for VAX-24 vs. PCV20 POST-DOSE 3 RESULTS This is not a complete study evaluating the concomitant administration of VAX-24 with other vaccines. The findings presented are limited in scope and are not necessarily indicative of how VAX-24 would perform in studies designed to assess concomitant administration. The IEP3 includes eligible subjects who received the same vaccine across all 4 doses, with valid PD4 IgG or OPA assay results based on blood sample collected within protocol-defined window, and without protocol deviations that may interfere with PD4 immune response. The IEP3 + Flu population includes all eligible subjects from the IEP3 population and an additional 9 participants who followed protocol and received a flu vaccine.
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0.0 0.5 1.0 1.5 2.0 10A - IEP4 + Flu 10A - IEP4 9V - IEP4 + Flu 9V - IEP4 8 - IEP4 + Flu 8 - IEP4 7F - IEP4 + Flu 7F - IEP4 6B - IEP4 + Flu 6B - IEP4 6A - IEP4 + Flu 6A - IEP4 5 - IEP4 + Flu 5 - IEP4 4 - IEP4 + Flu 4 - IEP4 3 - IEP4 + Flu 3 - IEP4 1 - IEP4 + Flu 1 - IEP4 0.0 0.5 1.0 1.5 2.0 33F - IEP4 + Flu 33F - IEP4 23F - IEP4 + Flu 23F - IEP4 22F - IEP4 + Flu 22F - IEP4 19F - IEP4 + Flu 19F - IEP4 19A - IEP4 + Flu 19A - IEP4 18C - IEP4 + Flu 18C - IEP4 15B - IEP4 + Flu 15B - IEP4 14 - IEP4 + Flu 14 - IEP4 12F - IEP4 + Flu 12F - IEP4 11A - IEP4 + Flu 11A - IEP4 November 4, 2025 GMR . 59 Consistently Improved Immunogenicity Responses Evidenced in Mid Dose VAX-24 PD4 IgG GMRs Compared to PCV20 Including Subjects Who Received Flu Vaccination IgG Geometric Mean Ratios for VAX-24 vs. PCV20 This is not a complete study evaluating the concomitant administration of VAX-24 with other vaccines. The findings presented are limited in scope and are not necessarily indicative of how VAX-24 would perform in studies designed to assess concomitant administration. POST-DOSE 4 RESULTS The IEP4 includes eligible subjects who received the same vaccine across all 4 doses, with valid PD4 IgG or OPA assay results based on blood sample collected within protocol-defined window, and without protocol deviations that may interfere with PD4 immune response. The IEP4 + Flu population includes all eligible subjects from the IEP4 population and an additional 12 participants who followed protocol and received a flu vaccine. Population: Immunogenicity Evaluable Population (IEP): 119 IEP + Concomitant Flu Vaccine: 130
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VAX-24 Showed Dose-Dependent Immune Responses and Little to No Evidence of Carrier Suppression 60November 4, 2025
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0.0 0.5 1.0 1.5 2.0 2.5 19F 19A 18C 9V 7F 6B 3 IgG GMR Supports Dosing Strategy for Ongoing VAX-31 Infant Phase 2 Study Dose Response Evidenced PD3 Across Most Serotypes 61November 4, 2025 DOSE-DEPENDENT IMMUNOGENICITY OBSERVED ACROSS DOSE RANGE1 LITTLE TO NO CARRIER SUPPRESSION EVIDENCED BY SIMILAR PERFORMANCE ACROSS DIFFERENT LEVELS OF PROTEIN CARRIER CONTENT (1) Data represent 7 STs dosed at 1.1, 2.2 and 4.4 mcg. (2) 15C coverage due to cross protection against 15B. The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 3 on slide 16. PD3 IgG GMR GMR Dose- Dependent Responses Demonstrate Potential for Optimization 1 4 5 6A 8 10A 11A 12F 14 15B 22F 23F 33F 2 9N 17F 20C 0.1 1 10 IgG GMCs mcg/mLs (95% CI) VAX-24 Mid Dose VAX-24 Mixed Dose PD3 IgG GMC 17 STs dosed at 2.2 mcg at both Mid and Mixed Doses2 POST-DOSE 3 RESULTS
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1 4 5 6A 8 10A 11A 12F 14 15B 22F 23F 33F 2 9N 17F 20C 0.1 1 10 IgG GMCs mcg/mLs (95% CI) VAX-24 Mid Dose VAX-24 Mixed Dose 0.0 0.5 1.0 1.5 2.0 2.5 19F 19A 18C 9V 7F 6B 3 IgG GMR Supports Dosing Strategy for Ongoing VAX-31 Infant Phase 2 Study Dose Response Evidenced PD4 Across Most Serotypes 62November 4, 2025 DOSE-DEPENDENT IMMUNOGENICITY OBSERVED ACROSS DOSE RANGE1 LITTLE TO NO CARRIER SUPPRESSION EVIDENCED BY SIMILAR PERFORMANCE ACROSS DIFFERENT LEVELS OF PROTEIN CARRIER CONTENT PD4 IgG GMR GMR Dose- Dependent Responses Demonstrate Potential for Optimization PD4 IgG GMC 17 STs dosed at 2.2 mcg at both Mid and Mixed Doses2 POST-DOSE 4 RESULTS (1) Data represent 7 STs dosed at 1.1, 2.2 and 4.4 mcg. (2) 15C coverage due to cross protection against 15B. The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 3 on slide 16.
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VAX-31 Infant Clinical Program 63November 4, 2025
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End Stage 1 - Proceed Dose 2 3-Stage, Dose-Finding Study Evaluating Safety, Tolerability and Immunogenicity of VAX-31 vs PCV20 in Infants VAX-31 Infant Phase 2 Study in ~900* Participants Exploring Multiple Doses Stage 1: Dose Escalation (n=48)Randomized Screen VAX-31 Low Dose PCV20 Dose 1 VAX-31 Middle Dose PCV20 VAX-31 High Dose PCV20 Dose 1 Dose 1 Stages 2 & 3: Main Study (n~900*) Randomized Screen All Stages: PCV20: n~200 All Stages: VAX-31 Middle Dose (2.2mcg¹): n~200 All Stages: VAX-31 High Dose (3.3mcg¹): n~200 Stage 3: VAX-31 Optimized Dose (4.4mcg/3.3mcg): n~200 Stages 1-2: VAX-31 Low Dose (1.1mcg¹): n~100 (enrollment complete) Age 2 months Dose 1 4 months 6 months 7 months 12-15 months Dose 2 Dose 3 Primary Series Immunogenicity Endpoint Dose 4 Long-Term Safety 13-16 months Booster Immunogenicity Endpoint Stage 1 (safety review; completed): The safety and tolerability of VAX-31 was evaluated at three dose levels (Low, Middle and High) and compared to PCV20 in 48 infants in a dose-escalation approach. Stage 2 (modified and incorporated into Stage 3): Evaluating the safety, tolerability and immunogenicity of VAX-31 at the same three dose levels and compared to PCV20. The study includes a primary immunization series with doses given at two, four and six months of age, followed by a booster dose at 12-15 months of age. Stage 3 (initiated): The modified study, including the VAX-31 Optimized Dose arm, is currently in the third and final stage. The Middle and High Dose arms are continuing in Stage 3 as planned. All participants will be evaluated for safety through six months after the booster dose. Age 2 months Age 2 months Age 2 months 64(*) n~900 inclusive of the 48 subjects from Stage 1, ~352 subjects from Stage 2, and ~500 subjects expected to be enrolled in Stage 3. (1) Except serotypes 1, 5 and 22F, which were dosed at 1.65mcg, 3.3mcg, and 4.4mcg, respectively. 6 months November 4, 2025
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Study Safety, Tolerability and Immunogenicity Key Outcome Measures SAFETY AND TOLERABILITY OUTCOME MEASURES IMMUNOGENICITY OUTCOME MEASURES November 4, 2025 65 DAY 7 AFTER EACH DOSE 1 MONTH POST-DOSE 3* 1 MONTH POST-DOSE 4* 6 MONTHS POST-DOSE 4 • Solicited local reactions • Solicited systemic events • Unsolicited adverse events (AE) • Serious adverse events (SAE), new onset of chronic illnesses (NOCI) and medically attended adverse events (MAAE) • SAE, NOCI and MAAE • SAE, NOCI and MAAE • % of subjects achieving Immunoglobulin G (IgG) antibody concentration ≥0.35 mcg/mL • IgG Geometric Mean Concentration (GMC) • Opsonophagocytic activity (OPA) Geometric Mean Titer (GMT) • IgG GMC • % of subjects achieving IgG antibody concentration ≥.35 mcg/mL • % of subjects achieving IgG concentration ≥1.0 mcg/mL • OPA GMT • IgG and OPA Geometric Mean Fold Rise (GMFR) from pre-dose 4 to 1-month post-dose 4 • % of subjects achieving a 4-fold rise in IgG and OPA from pre- dose 4 to 1-month post-dose 4
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Non-PCV Pipeline 66November 4, 2025
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UNMET NEED • Group A Strep results in an estimated 800M cases of illness annually worldwide, including pharyngitis, or strep throat, and certain severe invasive infections and sequelae1 • Upgraded CDC threat given significant source of antibiotic Rxs driving resistance which has nearly tripled in past decade • Responsible for post-infectious immune-mediated rheumatic heart disease leading to over 300K deaths in 2015 • Highly prevalent in children and rate of invasive disease in adults > 65 has more than doubled (exceeding IPD rate in adults) VAX-A1: BROAD-SPECTRUM, MONOVALENT CONJUGATE VX • Designed to confer robust, boostable and durable protection against a broad-spectrum of subtypes of Group A Strep • Leverages site-specific conjugation to disease-specific carrier to expose mapped T- and B-cell epitopes • Proprietary conserved antigen – Polyrhamnose – conjugated to an immunogenic disease-specific carrier along with two conserved virulence factors PROGRAM STATUS • Partially funded by grant from CARB-X (consortium of BMGF, Wellcome Trust, U.S. Biodefense Agency (BARDA)). The grant provided total funding of $11.7 million upon the achievement of development milestones, the last of which was successfully achieved in 2Q:24. • Initiated IND-enabling activities in 2H:21 • Paused advancement beyond preclinical at this time while preserving the option to advance the program in the future KEY DATA November 4, 2025 67 Novel Conjugate Vaccine Designed to Provide Universal Protection Against a High Priority Pathogen VAX-A1: Group A Strep Conjugate Vaccine Program Mock SLO + C5a pep SpyAD-GACPR VAX-A1 (SLO + C5a pep + SpyAD-GACPR)0% 10% 20% 30% 0 10,000 20,000 30,000 2012 2014 2016 2018 Number of Invasive Cases Clindamycin Resistance Erythromycin Resistance Tetracycline Resistance Sharp increase in cases and resistance over past decade CDC. Antibiotic Resistance Threats in the United States, 2019. Atlanta, GA: US Department of Health and Human Services, CDC; 2019. BMGF = Bill & Melinda Gates Foundation. (1) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7152370/.
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VAX-GI: Shigella Vaccine Program (1) Lancet. 2018 Feb 24;391(10122):801-812. (2) https://www.who.int/publications/i/item/9789240036741. UNMET NEED • Shigella is a bacterial illness with no available preventative treatment • Estimated to cause 80-165 million cases of disease and 600,000 deaths annually, and most cases and deaths are among children. • With the aim of reducing morbidity and mortality due to the disease, the World Health Organization lists Shigella vaccine development as a priority goal2 VAX-GI: NOVEL SHIGELLA VACCINE • Development collaboration with the University of Maryland, Baltimore; supported with funding by two National Institutes of Health grants with total potential funding of up to $5.1M • Plan to pursue conjugate and protein-only approaches simultaneously • Conjugate approach: IpaB-LPS/IpaH/VirG; Protein-only approach: IpaB/IpaH/VirG PROGRAM STATUS • Decision on final candidate to be determined by a human challenge study conducted at the University of Maryland, Baltimore • Paused advancement beyond preclinical at this time while preserving the option to advance the program in the future MOA & KEY DATA • Targeting IpaB inhibits assembly of T3SS and toxin delivery to immune cells • Opsonophagocytosis and killing of bacteria November 4, 2025 68 Novel Shigella Vaccine to Prevent Widespread Global Morbidity & Mortality, Particularly in Children 0 2 4 6 8 10 12 14 0 20 40 60 80 100 Days after challenge % Survival * * * * VAX-GI: Conjugate Approach VAX-GI: Protein Only Approach Candidate Vaccine Antigen T3SS 0 2 4 6 8 10 12 14 0 20 40 60 80 100 Days after challenge % Survival IpaB 5µg IpaB-10µg IpaB-20µg sl Sf2a-IN * * AdjuPhos PBS * *
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69November 4, 2025 Key Corporate Highlights Cell-Free Protein Synthesis Enabled Pipeline Robust Pipeline with Multiple Novel Vaccines Aligned Critical Resources Large Market Opportunity for Lead PCV Franchise
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Appendix 70November 4, 2025
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71November 4, 2025 PPSV23 PCV13 PCV15 PCV20 PCV21 VAX-31 Total Coverage (US %)3 70.6% 34.4% 47.3% 61.1% 81.2% 94.9% (1) The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 1 on slide 16. (2) 15C coverage due to cross-reaction against 15B. 6C coverage due to cross-protection by 6A. (3) % of IPD caused in individuals ≥50 yrs of age in the U.S. in 2023 based on ABC surveillance data References: https://data.cdc.gov/Public-Health-Surveillance/1998-2023-Serotype-Data-for-Invasive-Pneumococcal-/qvzb-qs6p/about_data. VAX-31: • Positioned to provide unrivaled IPD coverage as the broadest-spectrum PCV to enter U.S. clinics; designed to increase coverage to approximately 95% of IPD circulating in U.S. adults • Includes serotypes to provide protection against both currently circulating and historically prevalent serotypes, with potential to surpass standard-of-care adult PCVs with 14-34% incremental coverage Spectrum of Coverage Drives Adoption in PCV Segment VAX-31 Designed to Increase Coverage to ~95% of IPD Circulating in U.S. Adults 18.75% 10.62% 6.35% 5.64% 5.39% 4.88% 4.78% 3.96% 3.86% 3.71% 3.35% 3.00% 2.90% 2.49% 2.34% 2.29% 1.98% 1.88% 1.83% 1.63% 1.58% 1.47% 1.37% 1.27% 0.97% 0.46% 0.25% 0.20% 0.20% 0.10% 0.10% 0.05% 0.05% 0.05% 0.05% 0.05% 0.00% 0.00% 0.00% 0.00% 0.00% 0.00% 2.00% 4.00% 6.00% 8.00% 10.00% 12.00% 14.00% 16.00% 18.00% 20.00% 3 22F 4 9N 23A 19F 20 15A 11A 35B 12F 16F 15B/C 23B 33F 8 7C 6A/C 31 19A 34 35F 10A 38 17F 7F 28A 9V 13 21 23F 10F 14 18A 18C 33A 1 2 5 6B 24F2 21
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72November 4, 2025 14.48% 13.79% 13.10% 9.66% 6.21% 6.21% 4.83% 4.83% 4.14% 3.45% 3.45% 3.45% 1.38% 1.38% 1.38% 1.38% 1.38% 0.69% 0.69% 0.69% 0.69% 0.69% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.69% 0.0% 0.00% 2.00% 4.00% 6.00% 8.00% 10.00% 12.00% 14.00% 16.00% 3 19F 15B/C 22F 15A 33F 23B 11A 35B 10A 23A 38 9N 19A 20 21 33A 18C 16F 35F 4 7F 31 1 2 5 6A/C 6B 7C 8 9V 12F 14 17F 23F Total Coverage (US %)4 47.6% 69.0% 71.7% 91.7% Vaxneuvance Prevnar20 VAX-24 VAX-31 (1) 15C coverage due to cross protection against 15B. (2) The serogroup 20 antigen contained in VAX-24 and VAX-31, formerly known as a 20B variant, has been officially reclassified as 20C. For additional details on serogroup 20, please see footnote 1 on slide 16. (3) Estimated AOM coverage in children under five, Grant et al, Characterization of Streptococcus pneumoniae isolates obtained from the middle ear fluid of US children, 2011–2021. In children under 18, VAX-31 is estimated to address ~80% of pneumococcal AOM: King LM et al. Pneumococcal Serotype Distribution and Coverage of Existing and Pipeline Pneumococcal Vaccines, The Journal of Infectious Diseases, 2025, jiaf376; https://doi.org/10.1093/infdis/jiaf376. (4) % of IPD caused in individuals <5 yrs of age in the U.S. in 2023 based on ABC surveillance data References: https://data.cdc.gov/Public-Health-Surveillance/1998-2023-Serotype-Data-for-Invasive-Pneumococcal-/qvzb-qs6p/about_data. 1 2 Pediatric Segment Represents Majority of ~$8B Pneumococcal Vaccine Market Spectrum of Coverage Drives Adoption in Vital Pediatric Population VAX-24: Broadest-spectrum profile designed to cover more serotypes than any pediatric pneumococcal vaccine on- market today. VAX-31: 31-valent PCV with potential to increase serotype coverage and address ~93% of acute otitis media.3