Phase II data found broad immune responses and a comparable safety profile for Pfizer’s 25vPnC vaccine, supporting its larger Phase III programme in infants.
Pfizer has reported encouraging Phase II results for its experimental 25-valent pneumococcal conjugate vaccine, 25vPnC, in infants, saying the shot generated immune responses to all 25 targeted serotypes and matched the safety and tolerability seen with its existing Prevnar 20 vaccine. The company said the findings strengthen the case for a larger paediatric Phase III programme now under way. According to Pfizer, the study data were shared as part of its broader push to broaden protection against pneumococcal disease in young children.
The most notable signal came from serotype 3, a strain that has long been difficult to control and is still responsible for a meaningful share of invasive cases in US children under five. Pfizer said antibody levels against serotype 3 were 8.8 times higher one month after the third dose and 15 times higher after the fourth dose, compared with Prevnar 20. The company also said the added serotypes in 25vPnC, including 15A, 23A, 23B, 24F and 35B, are estimated to account for about 30% more paediatric invasive pneumococcal disease cases in the US than Prevnar 20 covers.
Pfizer said the trial used a four-dose infant schedule and showed booster responses across the full set of serotypes after the final dose. It also said adverse events, systemic reactions and local reactions were broadly balanced between the two vaccine groups, and that investigators recorded no treatment-related serious adverse events. The company described the safety profile as consistent with what would typically be expected in healthy infants.
The results feed into a paediatric Phase III programme launched earlier this year, which Pfizer says includes three trials enrolling as many as 6,830 children and comparing 25vPnC with Prevnar 20. The company said the 25 serotypes in the candidate could cover roughly 84% of invasive pneumococcal disease cases among US children younger than five if development succeeds. Pfizer has also completed enrolment in a separate Phase III study designed to assess manufacturing consistency across three production lots, while it continues to advance a 35-valent adult vaccine candidate towards clinical testing.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
