Immunogenicity and Safety of 13-valent Pneumococcal Conjugate Vaccine in Children Previously Immunized With 7-valent Pneumococcal Conjugate Vaccine

Abstract

The 7-valent pneumococcal conjugate vaccine (PCV7) has proven highly effective in preventing diseases caused by Streptococcus pneumoniae; however, in some regions, serotype coverage is limited. A recently licensed 13-valent PCV (PCV13) was developed to provide additional coverage globally. Children previously vaccinated with PCV7 could benefit from supplemental vaccination with PCV13 to provide protection against the 6 additional serotypes in PCV13. This open-label study evaluated the immunogenicity and safety of administering PCV13 to healthy children previously vaccinated with PCV7. Children between 15 months and 2 years of age (group 1) received 2 doses of PCV13; children between 2 and 5 years (group 2) received 1 dose. Antibodies (immunoglobulin G) against the polysaccharide antigens in PCV13 were measured before vaccination and 1 month after the final dose. Solicited local and systemic adverse events (AEs) were collected for 7 days postvaccination. Unsolicited and serious AEs were collected throughout. A total of 284 subjects (group 1: n = 109; group 2: n = 175) had blood available for testing. Antipneumococcal immunoglobulin G geometric mean fold rises ranged from 2- to 19-fold for the PCV7 serotypes and from approximately 2- to 124-fold for the 6 additional serotypes. Additionally, postvaccination titers in excess of 0.35 μg/mL, the serologic correlate of immunity against pneumococcus for children, occurred in ≥98% of subjects in both groups for 12 of the 13 serotypes in PCV13. Slightly lower percentage of subjects, 94.5% and 92% of subjects in group 1 and group 2, respectively, had postvaccine titers for serotype 3 exceeding the serologic correlate of immunity. Reactogenicity was typically mild and self-limited, and unsolicited AEs reported were generally consistent with common childhood illnesses. PCV13 was safe and immunogenic when administered to children who had previously received PCV7, and can be used for supplemental vaccination to provide additional protection against the 6 additional serotypes.