Pfizer Inc. (PFE) has advanced its investigational 25-valent pneumococcal conjugate vaccine (25vPnC) into a pivotal Phase 3 pediatric program after Phase 2 results showed robust immune responses, including a markedly stronger response against serotype 3 compared to the current standard PREVNAR 20.
Strong Phase 2 Results
The Phase 2 study evaluated a four-dose series of 25vPnC in infants at 2, 4, 6 and 12-15 months. Results demonstrated an 8.8-fold higher immune response after Dose 3 and a 15-fold higher immune response after Dose 4 against serotype 3 compared to PREVNAR 20.
The candidate vaccine was well-tolerated, with a safety profile consistent with currently approved pneumococcal vaccines.
Pfizer noted that the investigational vaccine is designed to cover 25 serotypes, including five additional strains not covered by PREVNAR 20, potentially broadening protection to about 90% of disease-causing serotypes in children under five.
Launch of Phase 3 Pediatric Program
Based on the encouraging Phase 2 data and regulatory discussions, Pfizer initiated its pivotal Phase 3 pediatric program in May 2026. The study will enroll up to 2,400 children, randomized to receive either 25vPnC or PCV20, across the same four-dose schedule.
Annaliesa Anderson, Pfizer's Chief Vaccines Officer, said the results "reinforce confidence in a next-generation vaccine designed to expand protection across serotypes while improving responses to key residual disease drivers such as serotype 3."
Adult Program Advances to Fifth-Generation Candidate
In parallel, Pfizer announced plans to move directly to a fifth-generation adult pneumococcal vaccine candidate covering 35 serotypes, with clinical development expected to begin by the end of 2026 pending regulatory alignment.
This candidate is designed to further expand serotype coverage and enhanced immunogenicity for critical strains, including serotype 3, using Pfizer's proprietary next-generation technology.
PFE has traded between $22.81 and $28.75 over the past year. The stock closed Tuesday's trading at $25.66, up 1.30%. In pre-market trading the stock is at $25.69, up 0.04%.
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Business News
May 15, 2026 15:25 ET Apart from the confirmation of Kevin Warsh as the next Fed chair, the main news on the economics front this week included key price data from the U.S. and the first quarter economic growth figures from major economies. Both consumer prices and producer costs have started to reflect the effect of supply shocks due to the Middle East conflict. In Europe, GDP data was in focus, while inflation data from China dominated the news flow in Asia.