VAX-31 - (OPUS-1)

October 5, 2026: Vaxcyte (NASDAQ: PCVX) reported positive topline results from the pivotal Phase 3 OPUS-1 trial of VAX-31, a 31-valent pneumococcal conjugate vaccine candidate for prevention of invasive pneumococcal disease and pneumococcal pneumonia in adults.

In adults 50 and older, VAX-31 met all prespecified co-primary immunogenicity endpoints: all 28 serotypes shared with Prevnar 20 (PCV20) and/or Capvaxive (PCV21) met noninferiority (lower bound of 95% CI >0.667), and the three serotypes unique to VAX-31 plus cross-reactive serotype 20B met superiority (LBCI >2.0). In adults 18-49, VAX-31 met the primary immunobridging endpoint, achieving noninferiority across all 32 serotype comparisons versus adults 50-64.

Safety was similar to PCV20 and PCV21 across all ages; reactogenicity was generally mild to moderate, no vaccine-related serious adverse events were reported, and no discontinuations were due to adverse events.

In comparator-specific analyses, VAX-31 met noninferiority for 20/20 shared serotypes versus PCV20 and 17/19 versus PCV21; serotypes 3 and 12F missed the >0.667 threshold versus PCV21 but met the historical >0.5 threshold.

Upcoming catalysts: OPUS-2 and OPUS-3 Phase 3 adult data are expected in 1H 2027, followed by a manufacturing consistency study and a planned BLA submission in 1H 2028. VAX-31 infant Phase 2 topline data are also expected by the end of 1H 2027.