nine-valent pneumococcal conjugate vaccine

The nine-valent pneumococcal conjugate vaccine (PCV-9) is an investigational biologic vaccine developed by Wyeth (now Pfizer) in collaboration with the National Institute of Allergy and Infectious Diseases (NIAID). It is a conjugate vaccine containing capsular polysaccharide antigens from nine *Streptococcus pneumoniae* serotypes (1, 4, 5, 6B, 9V, 14, 18C, 19F, and 23F), each individually conjugated to the CRM197 carrier protein. This conjugation enhances the immunogenicity of the polysaccharides by inducing a T-cell dependent immune response, which is particularly effective in infants and young children. PCV-9 was evaluated in a landmark Phase III trial in Gambian infants, where it demonstrated significant efficacy against invasive pneumococcal disease and radiological pneumonia. Although the vaccine showed clinical success, it was never commercialized as a final product, serving instead as a developmental precursor to higher-valent licensed vaccines such as the 13-valent Prevenar 13.

Other names

9-valent pneumococcal conjugate vaccine9vPCV