Immunogenicity of 13-Valent Pneumococcal Conjugate Vaccine Administered According to 4 Different Primary Immunization Schedules in Infants A Randomized Clinical Trial

RESULTS The primary outcome, GMCs at 1 month after the booster dose, was not significantly different between schedules for 70 of 78 comparisons. The 2-4-6 schedule was superior to the 2-3-4 schedule for serotypes 18C (10.2 μg/mL [95% CI, 8.2-12.7] vs 6.5 μg/mL [95% CI, 5.4-7.8]) and 23F (10.9 μg/mL [95% CI, 9.0-13.3] vs 7.3 μg/mL [95% CI, 5.8-9.2]) and superior to the 2-4 schedule for serotypes 6B (8.5 μg/mL [95% CI, 7.1-10.2] vs 5.1 μg/mL [95% CI 3.8-6.7]), 18C (6.6 μg/mL [95% CI, 5.7-7.7]), and 23F (7.2 μg/mL [95% CI, 5.9-8.8]). For serotype 1, the 3-5 schedule (11.7 μg/mL [95% CI, 9.6-14.3]) was superior to the other schedules. Geometric mean concentrations for all 13 serotypes ranged between 1.6 and 19.9 μg/mL. Secondary outcomes demonstrated differences 1 month after the primary series. The 2-4-6 schedule was superior compared with the 3-5, 2-3-4, and 2-4 schedules for 3, 9, and 11 serotypes, respectively. Differences between schedules persisted until the booster dose. CONCLUSIONS AND RELEVANCE The use of 4 different PCV13 immunization schedules in healthy term infants resulted in no statistically significant differences in antibody levels after the booster dose for almost all serotypes. The choice of PCV schedule will require a balance between the need for early protection and maintaining protection between the primary series and the booster.