Pfizer reports positive Phase II data for 25-valent pneumococcal vaccine in infants

Pfizer reported positive results from its Phase II trial evaluating the 25-valent pneumococcal conjugate vaccine candidate, PF-07872412 (25vPnC), in infants. The trial compared 25vPnC to PREVNAR 20 (PCV20) over a four-dose schedule at two, four, six, and 12-15 months of age, focusing on tolerability, immunogenicity, and safety.

Key Phase II data shared at the International Society of Pneumonia & Pneumococcal Diseases meeting in Denmark showed that geometric mean titers for serotype 3 were 8.8-fold higher with 25vPnC compared to PREVNAR 20, one month after the third dose. After the fourth dose, the titers were approximately 15-fold higher with 25vPnC than PCV20.

The vaccine candidate is projected to provide coverage for up to 90% of disease-causing serotypes in children under five years, with around 15% attributed to serotype 3. The vaccine expands coverage by adding five new serotypes to the current 20-valent vaccine.

The randomised Phase II study in healthy infants began enrolment in July 2024. Participants received either 25vPnC or PCV20, with safety, tolerability, and immunogenicity assessed at regular intervals post-vaccination. Local reactions included redness, swelling, or pain at the injection site, consistent with current vaccines.

Phase III studies commenced this month to further evaluate the safety, tolerability, and immunogenicity of 25vPnC versus PCV20 in up to 2,400 healthy children. In the adult segment, Pfizer intends to introduce a fifth-generation vaccine with 35 serotypes, entering clinical development later this year.