Trial Design Finalized in Consultation and Alignment with U.S. Food and Drug Administration Study Designed to Establish a New Standard for Adult Pneumococcal Conjugate Vaccines Through Head-to-Head Safety, Tolerability and Immunogenicity Comparisons of VAX-31 with Capvaxive (PCV21) and Prevnar 20 (PCV20), the Current Standards of Care Company Expects to Report Topline Safety, Tolerability and Immunogenicity Data for OPUS Phase 3, Noninferiority Trial in the Fourth Quarter of 2026 and Initiate Additional Phase 3 Studies in 2026 with Readouts in 2027, Supporting Planned BLA Submission VAX-31 is Designed to Cover ~95% of Invasive Pneumococcal Disease (IPD) and ~88% of Pneumococcal Pneumonia in U.S. Adults Aged 50+, with Potential to Provide an Incremental 14-34% Broader IPD Coverage and 19-31% Broader Pneumonia Coverage than Standard-of-Care Vaccines VAX-31 Aims to Advance Adult Pneumococcal Protection by Maintaining Critical Pressure on Both Currently Circulating and Long-Established, Historically Disease-Causing Serotypes, While Maintaining or Improving Immune Responses SAN CARLOS, Calif., Dec. 08, 2025 (GLOBE NEWSWIRE) -- Vaxcyte, Inc. (Nasdaq: PCVX), a clinical-stage vaccine innovation company, today announced that the first participants were dosed in the OPUS (OPA-based Pivotal U.S. Study) Phase 3 pivotal, noninferiority trial evaluating VAX-31 for the prevention of invasive pneumococcal disease (IPD) and pneumonia in adults.