Objective: The safety and immunogenicity of the 10-valent pneumococcal nontypeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) in preterm infants were assessed in this study.
Methods: Three parallel groups of infants received 3-dose primary immunization with PHiD-CV at 2, 4, and 6 months of age and a booster dose at 16 to 18 months: preterm I (gestation period ≥ 27 and <31 weeks, N = 50); preterm II (≥31 and <37 weeks, N = 87); and term (≥37 weeks, N = 149). Solicited symptoms and adverse events were recorded. Immune responses to PHiD-CV and coadministered vaccine antigens were measured.
Results: The incidence of solicited general symptoms was similar across groups, and the frequency of grade 3 general symptoms was low. Incidences of redness and swelling were generally lower in preterm infants. PHiD-CV was immunogenic for each of the 10 vaccine pneumococcal serotypes (postprimary, ≥92.7% of infants reached enzyme-linked immunosorbent assay antibody concentrations ≥ 0.2 μg/mL and postbooster, ≥97.6%) and for protein D, with a trend for lower postprimary geometric mean antibody concentrations and opsonophagocytic activity (OPA) titers in preterm infants for some pneumococcal serotypes. Postbooster, ≥91.9% of subjects in each group had an OPA titer ≥ 8 for each of the vaccine serotypes. Pneumococcal antibody concentrations and OPA titers after priming and booster vaccination were comparable between the 2 preterm groups.
Conclusions: PHiD-CV was well tolerated and immunogenic in preterm infants when given as a 3-dose primary vaccination, with robust enzyme-linked immunosorbent assay antibody and OPA booster responses in the second year of life.
Trial registration: ClinicalTrials.gov NCT00390910 NCT00609492.