Pfizer announced robust Phase 2 results for its investigational 25-valent pneumococcal conjugate vaccine candidate (25vPnC) for infants. The company presented this data at IDWeek 2026. A four-dose series of the vaccine elicited strong immune responses against all 25 serotypes. Its safety and tolerability profile was comparable to the currently approved PREVNAR 20.
The new candidate includes five additional serotypes not covered by PREVNAR 20. This potentially offers broader protection against invasive pneumococcal disease. The 25vPnC vaccine generated a significantly enhanced immune response against serotype 3, a historically challenging strain. Antibody levels were approximately 15-fold higher than PREVNAR 20 after the fourth dose. These results support the vaccine's ongoing Phase 3 development program.