Maternal immunization with pneumococcal polysaccharide vaccine: Persistence of maternal antibodies in infants

Abstract

Objective: To evaluate the level and the persistence of maternal antibodies in infants after maternal immunization with pneumococcal polysaccharide vaccine (Pn23V). Methods: 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. Results: 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. Conclusion: Despite the antibody level's decline, at 6 months of age, proportions > 0.35 lg/ml remained higher in the infants of vaccinated mothers than controls for all three serotypes.