Vaxcyte says 31-valent pneumococcal vaccine met all primary goals in pivotal adult Phase 3 trial

Vaxcyte's next-generation pneumococcal vaccine hit its marks in a pivotal trial. The company said Monday that VAX-31, its 31-valent pneumococcal conjugate vaccine candidate, met all prespecified primary endpoints in OPUS-1, the pivotal adult Phase 3 trial that Vaxcyte plans to use as the cornerstone of a U.S. Biologics License Application.

The trial dosed 4,047 participants at about 30 U.S. sites. Adults 50 and older were randomized to a single dose of VAX-31, Prevnar 20 (PCV20) or Capvaxive (PCV21), with immune responses measured one month later.

In that older group, all 28 serotypes VAX-31 shares with PCV20 and/or PCV21 met the noninferiority criterion, and the three serotypes unique to VAX-31, plus cross-reactive serotype 20B, met the superiority criterion, according to a press release filed with an 8-K. In a separate cohort of adults aged 18 to 49, VAX-31 met the immunobridging goal across all 32 serotype comparisons.

The company said the vaccine was well tolerated, with a safety profile similar to both comparators. No serious adverse events were considered related to the study vaccines, and no participants dropped out because of side effects.

The prespecified individual comparisons were not a clean sweep. Head to head, VAX-31 met the noninferiority bar for 20 of 20 serotypes shared with PCV20 but 17 of 19 shared with PCV21. Serotypes 3 and 12F missed the stricter threshold against PCV21 while clearing the historical, looser one.

That matters because Vaxcyte expects the PCV21 comparison "to be a particular focus of FDA review," Chief Scientific Officer and COO James Wassil said in the release.

Next up are results from the OPUS-2 and OPUS-3 adult Phase 3 trials in the first half of 2027, followed by a manufacturing consistency study. Vaxcyte plans to submit its BLA in the first half of 2028.

By the numbers

• Participants dosed: 4,047 at about 30 U.S. sites
• Shared serotypes meeting noninferiority (adults 50+): 28 of 28
• Unique serotypes plus 20B meeting superiority: 4 of 4
• Individual noninferiority vs. PCV21: 17 of 19 serotypes
• OPUS-2 and OPUS-3 readouts: first half of 2027
• Planned BLA submission: first half of 2028

Sources

1. Vaxcyte, Inc. Form 8-K (Items 7.01, 8.01), filed Oct. 5, 2026, accession 0001193125-26-413168
2. Vaxcyte press release, Exhibit 99.1, dated Oct. 5, 2026

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