Vaxcyte, Inc. (PCVX), a clinical-stage vaccine innovation company, announced that the first participants have been dosed in the OPUS-3 Phase 3 trial evaluating VAX-31, its next-generation 31-valent pneumococcal conjugate vaccine (PCV) candidate, in adults who have previously received lower-valency pneumococcal vaccines.
Pneumococcal disease, caused by Streptococcus pneumoniae, remains a major public health challenge, leading to invasive infections such as meningitis and bacteremia, as well as pneumonia and otitis media. In the United States alone, pneumococcal pneumonia is estimated to result in about 225,000 adult hospitalizations annually, with drug-resistant strains posing a serious threat.
The OPUS-3 study is a randomized, double-blind, active-controlled trial enrolling approximately 720 adults aged 50 and older across 30 U.S. sites. Participants with prior vaccination histories (PPSV23, PCV20, or other licensed pneumococcal vaccines) will be randomized to receive either VAX-31 or PCV20.
The trial will assess safety, tolerability, and immunogenicity, including whether VAX-31 can boost serotype-specific immune responses in previously vaccinated adults.
Vaxcyte's broader Phase 3 adult program for VAX-31 includes:
•OPUS-1, a pivotal noninferiority trial in pneumococcal-naïve adults, with topline data expected in fourth quarter of 2026.
•OPUS-2, evaluating concomitant administration of VAX-31 with a seasonal influenza vaccine, with topline data anticipated in the first half of 2027.
•OPUS-3, now underway in previously vaccinated adults, with topline data also expected in the first half of 2027.
VAX-31 is designed to cover approximately 95% of invasive pneumococcal disease and 88% of pneumococcal pneumonia in U.S. adults aged 50+, potentially providing 14-34% broader IPD coverage and 19-31% broader pneumonia coverage compared to current standard-of-care vaccines. The program, finalized in consultation with the FDA, is intended to support a planned Biologics License Application (BLA).
PCVX has traded between $27.66 and $86.44 over the past year. The stock closed Wednesday's trading at $55.35, up 0.67% and rose further in the pre-market to $55.40, up 0.09%.
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