1. Vaxcyte announces initiation of OPUS Phase 3 trial for VAX-31. 2. VAX-31 could provide up to 34% broader IPD coverage than current vaccines. 3. Topline data expected in Q4 2026; pivotal for BLA submission. 4. Company's VAX-31 aims to establish a new standard in adult vaccinations.
FAQ
Why Very Bullish?
VAX-31's potential for superior efficacy and broader coverage is substantial. Historical spikes from vaccine advancements suggest similar positive market reactions.
How important is it?
The success of VAX-31 could reshape the pneumococcal vaccine market, leading to increased market share and revenues.
Why Long Term?
Topline data and FDA BLA submission timelines are critical for long-term investor sentiment and market positioning.
Vaxcyte Announces Start of OPUS Phase 3 Trial for VAX-31 Pneumococcal Vaccine
Vaxcyte, Inc. (Nasdaq: PCVX), a clinical-stage vaccine innovation company, has initiated the OPUS Phase 3 pivotal, noninferiority trial for its novel pneumococcal vaccine, VAX-31. As of December 8, 2025, the first participants have been dosed in this critical study aimed at evaluating VAX-31 for the prevention of invasive pneumococcal disease (IPD) and pneumonia in adults. This trial is expected to enroll approximately 4,000 participants and is aligned with the U.S. Food and Drug Administration (FDA) guidelines.
Trial Objectives and Design
The OPUS trial is designed to establish a new standard for adult pneumococcal conjugate vaccines. It will perform head-to-head comparisons of VAX-31 against existing vaccines, specifically Capvaxive (PCV21) and Prevnar 20 (PCV20). The goal is to assess the safety, tolerability, and immunogenicity of VAX-31, particularly in adults aged 50 and older, while also considering immunogenic responses in younger adults aged 18-49.
- Primary immunogenicity goals include demonstrating noninferiority based on the opsonophagocytic activity (OPA) geometric mean ratio (GMR) when comparing VAX-31 to PCV21 and/or PCV20.
- Furthermore, superiority will be evaluated for specific serotypes unique to VAX-31.
- Results from the OPUS trial are expected in the fourth quarter of 2026, which will support a future Biologics License Application (BLA).
Potential Impact of VAX-31
VAX-31 is anticipated to cover approximately 95% of invasive pneumococcal disease and 88% of pneumococcal pneumonia in U.S. adults aged 50 and older. The vaccine has the potential to provide between 14-34% broader IPD coverage and 19-31% broader pneumonia coverage compared to standard vaccines currently in use.
“The initiation of our adult Phase 3 program marks a major milestone,” said Grant Pickering, CEO of Vaxcyte. He emphasized that VAX-31 has the potential to expand disease and serotype coverage while ensuring high immunogenicity levels for sustainable protection.
Addressing Pneumococcal Disease Risks
Pneumococcal disease remains a significant threat to adults, particularly as new serotypes emerge that are not adequately addressed by existing vaccines. "By leveraging our advanced conjugation technology, our next-generation VAX-31 aims to maintain pressure on both circulating and historically significant serotypes,” said Jim Wassil, COO of Vaxcyte.
About the OPUS Trial
The OPUS Phase 3 trial is a randomized, double-blind, active-controlled study. It will assess the safety, tolerability, and immunogenicity of VAX-31 in healthy U.S. adults aged 50 years and older, with an additional cohort of those aged 18-49. Safety assessments will continue for six months following vaccination.
- Approximately 3,560 participants aged ≥50 years will receive a single dose of VAX-31, PCV21, or PCV20.
- About 440 participants aged 18-49 will be randomized to receive either VAX-31 or PCV20.
Looking Ahead
Vaxcyte is on track to announce topline data from the OPUS trial in late 2026, with further Phase 3 studies expected to yield additional results in 2027. These findings will not only support a potential BLA filing but will also contribute to creating post-licensure evidence of VAX-31's efficacy in the adult population.