Vaxcyte (PCVX) Study result summary

Trial design and opportunity

• OPUS-1 was a randomized, double-blind, active-controlled Phase 3 trial in 4,047 adults: 3,572 aged 50+ and 475 aged 18–49; immune responses were assessed one month after a single dose.

• VAX-31 is an investigational 31-valent PCV designed to cover 95% of U.S. invasive pneumococcal disease and 88% of pneumococcal pneumonia in adults 50+, adding 13–36% and 19–31% coverage, respectively, versus currently available adult PCVs.

Immunogenicity results

• In adults 50+, VAX-31 met all 32 prespecified co-primary assessments: noninferiority for all 28 shared serotypes and superiority in four comparisons covering three unique serotypes and cross-reactive 20B.

• VAX-31 met noninferiority for 20/20 serotypes shared with PCV20 and 17/19 shared with PCV21; serotypes 3 and 12F missed the prespecified threshold versus PCV21 but exceeded the historical threshold and met the threshold versus PCV20.

• Immunobridging met noninferiority across all 32 evaluated responses between adults aged 18–49 and 50–64.

Safety and tolerability

• VAX-31 was well tolerated, with a safety profile similar to PCV20 and PCV21; reactions were mostly mild to moderate, generally resolved within 48 hours, and were consistent with comparators across age groups.

• No serious adverse events were considered vaccine-related, no participants discontinued due to adverse events, and all four reported deaths were assessed as unrelated to vaccination.