Objective: Invasive pneumococcal disease rates have declined since immunization with 7-valent pneumococcal conjugate vaccine (PCV7) (Prevenar/Prevnar [Wyeth Pharmaceuticals, Philadelphia, PA]) became routine. Certain nonvaccine Streptococcus pneumoniae serotypes (1, 3, 5, 6A, 7F, and 19A) still cause significant morbidity and mortality. The safety and immunogenicity of PCV7 were compared with those of 13-valent PCV (PCV13), which contains saccharides from serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F conjugated to CRM(197).
Patients and methods: Infants were randomly assigned to receive PCV13 or PCV7 at ages 2, 4, and 6 months with other vaccines. Post-third-dose antibodies to each pneumococcal polysaccharide were measured by immunoglobulin G enzyme-linked immunosorbent assay. Antibacterial functional antibodies were measured by opsonophagocytic assay (OPA).
Results: Subjects received PCV13 (n = 122) or PCV7 (n = 127). All PCV13 serotypes were immunogenic, with 88% to 98% of infants achieving antibody concentrations of > or =0.35 microg/mL to shared PCV7 serotypes. For the 6 additional serotypes, 97% to 100% of PCV13-vaccinated infants achieved antibody concentrations of > or =0.35 microg/mL. Geometric mean antibody concentration for PCV13 recipients ranged from 1.32 microg/mL (serotype 23F) to 4.26 microg/mL (serotype 14). The ratio of OPA geometric mean titers for the 7 shared serotypes (PCV13:PCV7) ranged from 0.6 to 1.4, suggesting no clinically meaningful differences. For PCV13-only serotypes, OPA geometric mean titers were significantly higher in the PCV13 group than in the PCV7 group. Local reactions and systemic events were similar between groups.
Conclusions: PCV13 was well tolerated and immunogenic, with most infants developing antipolysaccharide antibody concentrations of > or =0.35 microg/mL, as well as OPA responses, to each of the 13 serotypes.
Trial registration: ClinicalTrials.gov NCT00205803.