Pneumococcal conjugate vaccine-elicited antibody persistence and immunogenicity and safety of 13-valent pneumococcal conjugate vaccine in children previously vaccinated with 4 doses of either 7-valent or 13-valent pneumococcal conjugate vaccine.

BACKGROUND:Pneumococcal conjugate vaccine (PCV) antibody persistence and immunologic memory responses may be indicative of protection in previously vaccinated children. In children vaccinated in a previous study with an infant/toddler regimen of 4 doses of PCV7, 4 doses of PCV13, or 3 doses of PCV7 (infant series) and a dose of PCV13 (toddler dose), this follow-on study evaluated antibody persistence ≥24 months after the toddler dose, and immunogenicity and safety of a follow-on dose of PCV13. METHODS:Children ≥3 years of age who had completed the initial study received 1 dose of PCV13 in this phase 3, open-label follow-on study in France. Serotype-specific anticapsular immunoglobulin G (IgG) and functional opsonophagocytic activity (OPA) were compared across the previous study vaccination groups, before, 4-7 days (IgG only), and 1 month after follow-on vaccination. Safety was assessed. RESULTS:Before follow-on vaccination, IgG and OPA levels for the PCV7 serotypes were comparable across vaccination groups, but were generally higher for the 6 additional serotypes in children who received PCV13 in the previous study. At both time points after the follow-on vaccination, IgG and OPA values for all 13 serotypes increased, those for the PCV7 serotypes were similar across vaccination groups, but concentrations for the additional serotypes were higher in children who had received PCV13 in the previous study. PCV13 was well-tolerated. CONCLUSIONS:Antibody persistence and rapid responses after a follow-on dose of PCV13 suggest that even a single toddler dose of PCV13 is likely to provide protection against the 6 additional PCV13 serotypes.