D Chlebna-Sokół, E Szynczewska

Abstract

Background: The aim of this study was to assess the levels of antibodies after vaccination of heptavalent conjugate vaccine against Streptococcus pneumoniae (PCV7) in children born prematurely and to check whether there is a relationship between gestational age, birth weight, health condition at birth, and gender and immunogenicity of the PCV7. Methods: The study included 60 pre-term infants. Each child was vaccinated four times (2, 4, 6 and 16 months) with PCV7. Assessment of the level of antibodies was performed before vaccination, 4 weeks after primary series, before and 4 weeks after the booster dose. Results: Immunisation showed an increase of the average concentration of antibodies for all serotypes in most subjects; however, there were differences between the various serotypes. We found statistically significant relationship between fetal age and the concentration of antibodies related to serotypes 4, 9V, 14, 18C prior to dosing booster and to19F after it. In light of the relationship between health condition at birth and the level of antibodies, there was a marginal but significant correlation for serotypes 4, 6B, 23F (after a full course of vaccinations). We also found that girls had statistically higher concentration of antibodies after receiving all four doses of the vaccine. Conclusions: Heptavalent vaccine against Streptococcus pneumoniae has been proven to be highly immunogenic in preterm infants, even with extremely low birth weight. Among the perinatal factors, gender and health condition at birth clearly affect the level of post-vaccination response; less effect was noted in relation to gestational age.