Associated or combined vaccination of Brazilian infants with a conjugate Haemophilus influenzae type b (Hib) vaccine, a diphtheria-tetanus-whole-cellpertussis vaccine and IPV or OPV elicits protective levels of antibodies against Hib

This study investigated the immunogenicity and safety of including a Haemop hilus influenzae type b vaccine (polyribosylribitol phosphate conjugated to tetanus toroid, PRP-T) in three different vaccination schemes: (1) PRP-T r econstituted with a combined diphtheria-tetanus-pertussis-inactivated polio virus vaccine (DTP-IPV//PRP-T); (2) PRP-T reconstituted with DTP and admini stered concomitantly with an oral poliovirus vaccine (DTP//PRP-T+OPV); and (3) PRP-T administered concomitantly with DTP at a different injection site and OPV (DTP + PRP-T + OPV). Vaccines were given at 2, 4, and 6 months of age. A total of 252 infants were enrolled, and randomly assigned to one of the three vaccination groups (84 infants in each group); 241 infants were f ollowed until the end of the study. Antibody production against PRP, diphth eria, tetanus and pertussis antigens was satisfactory for each vaccination scheme used. A good response to Hib vaccine was elicited in each group, and 3 months after the third vaccine dose, at least 97% of children in each gr oup had levels of PRP antibody considered to be seroprotective (>0.15 mu g/ ml), and over 90% of children in each group had levels over 1.0 mu g/ml. Th e solicited local and systemic adverse events following vaccination were mi ld in all groups and resolved within 4 days without medical intervention. W ith the exception of fever, which was more common after the second dose in children who received DTP-IPV//PRP-T, local and systemic reactions did not differ between the vaccination groups. Due to the practical advantages of c ombined vaccines, their use in routine immunization programs in developing countries is highly desirable. Our results show that Hib conjugate vaccine can be included in routine immunization programs that include either OPV or IPV with satisfactory immunogenicity and safety profiles. This flexible ap proach should facilitate the inclusion of the Hib conjugate vaccine in rout ine immunization programs on a world-wide scale. (C) 2000 Elsevier Science Ltd. All rights reserved.