Immunogenicity and Safety of 13-Valent Pneumococcal Conjugate Vaccine Given to Korean Children Receiving Routine Pediatric Vaccines

Background: The immunogenicity and safety of 13-valent and 7-valent pneumococcal conjugate vaccines (PCV13 and PCV7) were compared when administered with routine vaccines in Korea. Methods: Healthy infants (n = 180) were randomly assigned (1:1) to receive PCV13 or PCV7 at 2, 4, 6 (infant series) and 12 months (toddler dose). Immune responses 1 month after the infant series and toddler dose were measured by enzyme-linked immunosorbent assay and opsonophagocytic activity (OPA) assay. IgG antibody geometric mean concentrations and OPA functional antibody geometric mean titers were calculated. Safety was assessed. Results: After the infant series, for the 7 common serotypes, proportions of responders with IgG concentrations >= 0.35 mu g/mL were comparable (>= 97.6%) between groups; IgG geometric mean concentrations and OPA geometric mean titers were generally similar, but tended to be lower in the PCV13 group for some serotypes. For the 6 serotypes unique to PCV13, IgG geometric mean concentrations and OPA geometric mean titers were notably higher in the PCV13 group. Importantly, although PCV7 elicited IgG antibodies to PCV13 serotypes 5 and 19A, OPA responses were minimal, whereas serotype 6A elicited both IgG and OPA responses. These observations are consistent with at least some protection by PCV7 against 6A-mediated invasive pneumococcal disease, but no cross-protection for serotypes 5 and 19A. The toddler dose elicited higher IgG and OPA responses than postinfant series responses for most serotypes; however, for serotypes 3 and 14 only OPA responses were increased posttoddler dose. Vaccine safety profiles were similar. Conclusions: PCV13 is safe and immunogenic in Korean children. PCV13 should provide broader protection than PCV7.