BACKGROUND AND OBJECTIVE: Premature infants have a higher risk of invasive pneumococcal disease and are more likely to have lower vaccine responses compared with term infants. Increasingly, immunization schedules are including a reduced, 2-dose, pneumococcal conjugate vaccine priming schedule. Our goal was to assess the immunogenicity of 3 commonly used 13-valent pneumococcal conjugate vaccine (PCV13) priming schedules in premature infants and their response to a 12-month booster dose. METHODS: Premature infants (<35 weeks' gestation) were randomized to receive PCV13 at 2 and 4 months (reduced schedule); 2, 3, and 4 months (accelerated schedule); or 2, 4, and 6 months (extended schedule). All infants received a 12-month PCV13 booster. Serotypespecific pneumococcal immunoglobulin G (IgG) for PCV13 serotypes was measured by using enzyme-linked immunosorbent assay 1 month after the primary and booster vaccinations. RESULTS: A total of 210 infants (median birth gestation, 29+6 weeks; range, 23+2-34+6 weeks) were included. After the primary vaccination, 75% (95% confidence interval [CI], 62-85), 88% (95% CI, 76-95), and 97% (95% CI, 87-99) of participants had protective antibody concentrations for at least one-half the PCV13 serotypes for the reduced, accelerated, and extended schedules, respectively. After the booster vaccination, participants receiving the extended schedule had significantly lower (P < .05) geometric mean concentrations compared with reduced (for 9 of 13 serotypes) and accelerated (for 4 of 13 serotypes) schedules, but nearly all participations, regardless of schedule or serotype, had seroprotective IgG concentrations. CONCLUSIONS: A reduced priming schedule of PCV13 resulted in higher post-booster IgG concentrations but lower post-primary concentrations. The optimum vaccine schedule for preterm infants will therefore depend on when they are most at risk for invasive pneumococcal disease.
Kent, A., Ladhani, S. N., Andrews, N. J., Scorrer, T., Pollard, A. J., Clarke, P., … Waight, P. (2016). Schedules for pneumococcal vaccination of preterm infants: An RCT. Pediatrics, 138(3). https://doi.org/10.1542/peds.2015-3945