Pfizer reports strong Phase 2 immune responses for 25-valent pneumococcal vaccine
Pfizer said its investigational 25-valent pneumococcal conjugate vaccine produced strong immune responses in infants across all 25 serotypes in a Phase 2 study. The four-dose regimen had safety and tolerability comparable to PREVNAR 20, and serotype 3 antibody levels exceeded those seen with the older vaccine. The company is continuing Phase 3 development for the candidate.
Pfizer’s candidate, PF-07872412, was tested in a Phase 2 trial (NCT06524414) involving healthy infants who received four doses. Investigators reported immune responses across all 25 serotypes, including five added types: 15A, 23A, 23B, 24F and 35B. Local reactions, systemic events and adverse events were balanced against PREVNAR 20, with no related serious adverse events.
For serotype 3, antibody geometric mean concentrations were 8.8 times higher after dose three and about 15 times higher after dose four than with PREVNAR 20. Functional assay responses after dose four indicated booster effects across the target serotypes. Pfizer says the candidate is in Phase 3 and could target serotypes linked to roughly 84% of U.S. invasive pneumococcal disease cases in children under five.
If approved, a broader pediatric pneumococcal vaccine could lower some cases of invasive disease in young children, potentially reducing illness and disruption for families and pediatric care. Clinicians and immunization programs may weigh added serotype coverage against scheduling, cost and safety monitoring. Longer-term data would be needed to show whether trial immune responses translate into fewer infections across diverse populations.