HAEMOPHILUS-INFLUENZAE TYPE-B CONJUGATED VACCINE - FURTHER EVALUATION OF THE GENERAL SAFETY TEST

Background: Currently 4 Haemophilus influenzae b-conjugate vaccines, basically two different types, are licenced in Germany; type A-vaccine is a toxoid-conjugate without adjuvant, type B-vaccine is a membrane protein conjugate with an adjuvant. Clinical studies in young infants show a higher immunogenicity but faster decline of antibodies for typ B-vaccine when compared to type A-vaccines. The safety profil of all 4 vaccines together in one study is not yet available. To better assess the risk of potential side-effects we evaluated die general safety test for additional data. Methods: The general safety test was applied to the HIB-vaccines (HIB-D, HIB-CRM, HIB-T and HIB-OMP). After the observation period of 7 days the mice were sacrified for necropsy and histological examination of the organs. Including additional cytology of the spleen, blood-count and bacterial examination. Results: There were no abnormal findings in the mice immunized with the type A-vaccine; their spleen showed hyperplasia of the follicles typical for the post-vaccinal period. Mice immunized with type B-vaccine showed splenomegaly with cytological changes and an activation of the myelo- and haematopoesis. Furthermore, we found aseptical peritonitis with multiple granulomas. Conclusion: The results indicate slight differences in reactogenicity, especially in the local tolerance, for the different HIB -vaccines. Although using already licensed vaccines, HIB-vaccinated children should be carefully observed.