Vaxcyte Stock Soars on Positive Phase 3 Trial Results for Pneumococcal Vaccine

Vaxcyte Inc. (NASDAQ:PCVX) stock soared on Monday following positive results from its pivotal Phase 3 OPUS-1 trial for VAX-31, an investigational 31-valent pneumococcal conjugate vaccine. The trial evaluated the safety, tolerability, and immunogenicity of VAX-31 in adults to prevent invasive pneumococcal disease and pneumococcal pneumonia. These findings will support an upcoming Biologics License Application submission to the U.S. Food and Drug Administration.

The OPUS-1 trial met all prespecified co-primary immunogenicity endpoints in participants aged 50 and older. VAX-31 achieved noninferiority criteria across all 28 serotypes shared with existing vaccines Pfizer Inc.’s (NYSE:PFE) Prevnar 20 (PCV20) and/or Merck & Co Inc.’s (NYSE:MRK) Capvaxive (PCV21). The vaccine candidate also demonstrated superiority over the comparative vaccines for three unique serotypes and the cross-reactive serotype 20B.

The trial also assessed immunobridging in adults aged 18 to 49 compared to adults aged 50 to 64. VAX-31 met noninferiority criteria across all 321 serotype comparisons within this group. Safety evaluations confirmed strong tolerability with a profile comparable to PCV20 and PCV21 across all tested age groups. Researchers recorded no vaccine-related serious adverse events or trial discontinuations due to adverse effects.

Looking ahead, Vaxcyte plans to report data from the OPUS-2 and OPUS-3 adult Phase 3 trials in the first half of 2027. Additionally, management expects Phase 2 trial results for infant indications by the end of the first half of 2027. Vaxcyte shares were up 56.91% at $88.62 during premarket trading on Monday, reaching a new 52-week high.