Maternal Immunization with Pneumococcal Polysaccharide Vaccine: Persistence of Maternal Antibodies in Infants

Abstract

To evaluate the level and the persistence of maternal antibodies in infants after maternal immunization with pneumococcal polysaccharide vaccine (Pn23V). Pregnant women were assigned to two groups, during routine low-risk pre-natal visits. The first Group (VAC) received the Pn23V vaccine shortly after enrolment at 28 weeks or later, and the second Group (NO_VAC) received no vaccine. To investigate the antibody persistence, we collected blood samples from the mothers after 1 month of delivery and from the infants at 1 and 6 months of age. Antibody titers were measured for serotypes 1, 6B and 14. Geometric mean antibody concentrations of specific immunoglobulin G were significantly higher in the vaccinated group compared with unvaccinated controls for all three serotypes tested. Despite the antibody level's decline, at 6 months of age, proportions >0.35 μg/ml remained higher in the infants of vaccinated mothers than controls for all three serotypes.