Vaxcyte VAX-31 Phase 3 Results
Vaxcyte VAX-31 Phase 3 results met prespecified co-primary immunogenicity endpoints and noninferiority versus PCV20/PCV21, sending shares up 57%.
KEY TAKEAWAYS
- VAX-31 met all prespecified co-primary immunogenicity endpoints in adults 50 and older.
- OPUS-1 results will underpin a planned BLA submission to the FDA.
- OPUS-1 dosed 4,047 participants and showed a safety profile similar to PCV20 and PCV21.
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Vaxcyte, Inc. (Nasdaq: PCVX) said on Oct. 5, 2026, that VAX-31 met all prespecified co-primary immunogenicity endpoints in adults age 50 and older, according to its Phase 3 results. The company said the data will support a planned Biologics License Application (BLA).
Phase 3 Results and Serotype Coverage
VAX-31, a 31-valent pneumococcal conjugate vaccine designed to prevent invasive pneumococcal disease and pneumonia, met the company’s noninferiority threshold, defined as a lower bound of the confidence interval above 0.667. Vaxcyte reported that all 28 serotypes shared with Pfizer’s Prevnar 20 (PCV20) and Merck’s Capvaxive (PCV21) met this criterion, including 20 of 20 serotypes versus PCV20 and 17 of 19 versus PCV21. Serotypes 3 and 12F did not meet the 0.667 threshold against PCV21 but exceeded a historical 0.5 benchmark.
Secondary reports indicated that three serotypes unique to VAX-31, along with cross-reactive serotype 20B, met superiority criteria.
Trial Design and Safety
The OPUS-1 trial was a randomized, double-blind, active-controlled Phase 3 study evaluating a single high dose of VAX-31 in healthy, pneumococcal-naïve U.S. adults. The trial enrolled 4,047 participants at about 30 U.S. sites, including 3,572 adults age 50 and older and a separate cohort of 475 adults ages 18 to 49. Participants age 50 and older were compared with PCV20 and PCV21, while the younger cohort was compared with PCV20.
Vaxcyte said VAX-31 was well tolerated and had a safety profile similar to PCV20 and PCV21 across all age groups studied.
Regulatory Path and Events
Vaxcyte described the OPUS-1 results as the foundation for a planned BLA submission to the U.S. Food and Drug Administration, which would be subject to FDA review. The company released topline data at 6:00 a.m. ET on Oct. 5, 2026, and held a webcast and conference call at 8:00 a.m. ET the same day. The announcement was included as an exhibit in a Form 8-K filed Oct. 5.
VAX-31 remains an investigational vaccine candidate. OPUS-1 was a clinical trial and not an approval decision. The company’s filings did not indicate any FDA acceptance-for-review notice, priority-review designation, advisory-committee decision, or Prescription Drug User Fee Act (PDUFA) date.
