13-Valent pneumococcal conjugate vaccine (PCV13) in children partially immunized with 7-valent pneumococcal conjugate vaccine (PCV7): A phase 3, open-label trial

BackgroundAs 13-valent pneumococcal conjugate vaccine (PCV13) is introduced, children who began vaccination with 7-valent pneumococcal conjugate vaccine (PCV7) may complete their vaccination with PCV13. This open-label phase 3 study evaluated immunogenicity and safety of PCV13 in Swedish infants and toddlers previously given 1 or 2 doses of PCV7 during infancy.MethodsHealthy infants previously given PCV7 at ages 3 months (group 1; n = 118) or 3 and 5 months (group 2; n = 116) received PCV13 at ages 5 (group 1) and 12 months (both groups). IgG responses were assessed 1 month after each PCV13 dose and before the 12-month dose. Local reactions and systemic events were collected for 7 days postvaccination. Other adverse events were also collected.ResultsPost-5-month dose, IgG geometric mean concentrations (GMCs) in group 1 were 1.56–4.70 μg/ml for most PCV7 serotypes except 6B (0.40 μg/ml) and 23F (0.57 μg/ml) and 0.72–1.88 μg/ml for most of the 6 additional serotypes, except 6A (0.28 μg/ml). Post-12-month dose, IgG GMCs for the PCV7 serotypes were 2.93–9.63 μg/ml (group 1) and 3.33–9.30 μg/ml (group 2); and for the 6 additional serotypes, 1.85–14.65 μg/ml (group 1) and 1.34–13.16 μg/ml (group 2). GMCs increased by >4-fold in both groups from pre- to post-12-month dose. Proportions of subjects in group 1 with pneumococcal serotype-specific IgG concentrations ≥0.35 μg/ml (WHO-designated postprimary reference antibody level) post-5-month dose were 92.2–99.1% for most PCV7 serotypes except 6B (53.0%) and 23F (62.6%) and 80.9–100.0% for most of the 6 additional serotypes except 6A (36.8%). Local reactions and fever were mostly mild or moderate.ConclusionsPCV13 was immunogenic and safe in infants and toddlers previously partially immunized with PCV7. Even a single dose in an infant or toddler induces an immune response to the 6 additional serotypes.

► In Sweden, pneumococcal conjugate vaccine (PCV) is administered on a 2 + 1 schedule.
► Infants who had 1 or 2 infant doses of PCV7 completed their schedule with PCV13.
► IgG GMCs increased by >4-fold for all serotypes from pre- to post-12-month dose.
► PCV13 was safe and well tolerated.
► Even a single dose of PCV13 induces immune responses to the 6 additional serotypes.