[Seroconversion after vaccination against pertussis, Haemophilus influenzae type b and poliomyelitis in preterm infants].

OBJECTIVE: This study was aimed to determine the levels of antibodies against Bordetella pertussis, Haemophilus influenzae type b (Hib) and Poliovirus type 1 in preterm children after immunization with acellular pertussis (Infanrix-DTPa) and Hib conjugate (Hiberix) vaccines as well as inactivated vaccine against poliomyelitis (Imovax Polio). MATERIAL AND METHODS: 32 children were given 3 doses of Infanrix-DTPa and Hiberix vaccines as well as Imovax Polio vaccine. Samples of blood were taken from children 4 weeks after application the 3-rd dose of vaccines and compared with the initial levels of antibodies (seroconversion was evaluated in 32 children immunized with both infanrix-DTPa and Hiberix and in 20 ones immunized with Imovax Polio). We evaluated the postvaccinal immunity against Bordetella pertussis and Hib by means of Immunoenzymatic methods (ELISA), with commercially available test kits (Bordetella pertussis ELISA KIT, Genzyme Virotech GmbH, Russelsheim, Germany and BINDAZYME Human Anti Haemophilus Influenzae Enzyme Immunoassay Kit, The Binding Site, Birmingham, U.K.); antibodies against Poliovirus type 1 were assessed using neutralisation method. RESULTS: All the children (100%) demonstrated protective levels of antibodies after Immunization with 3-rd doses of Infanrix-DTPa and Hiberix. Only one child (5%) didn't respond when Imovax Polio was applied. The observed increase of postvaccinal antibodies titers as to all applied antigens was statistically significant (p < 0.05). No significant correlations between birth weight, gestational age and the achieved levels of postvaccinal antibodies were noticed. CONCLUSIONS: Our results prove that nearly all the preterm infants achieve the protective levels of antibodies against pertussis, Hib and poliomyelitis. Hiberix due to its high immunogenicity should be applied in the obligatory vaccination schedules, especially in preterm infants.