Immunogenicity and reactogenicity of a booster dose of diphtheria, tetanus, acellular pertussis and inactivated poliomyelitis vaccines given concurrently with Haemophilus type b conjugate vaccine or as pentavalent vaccine

Background. The high reactogenicity of whole cell pertussis vaccines discourages their use in children. While acellular pertussis vaccines are less reactogenic, their use in diphtheria-tetanus-acellular pertussis (DTPa)-based combinations with Haemophilus influenzae type b conjugate vaccine (Hib) and poliomyelitis vaccines must be evaluated. Objectives. To assess the immunogenicity and reactogenicity of a booster dose of diphtheria, tetanus, acellular pertussis and inactivated poliomyelitis vaccine (DTPa-IPV) given concurrently with Hib as a mixed vaccine or as separate injections, in comparison with a whole cell pertussis vaccine (DTPw-IPV-Hib). Materials and methods. This open, randomized, controlled study involved 145 healthy children ages 15 to 24 months. Immunogenicity was evaluated for all vaccine antigens, and reactogenicity was assessed with diary cards. Results. Serum antibody responses to all vaccine antigens was at least as good as that observed with the pentavalent whole cell vaccine. DTPa-IPV was well-tolerated and less reactogenic than the DTPw-IPV vaccine. Administration of DTPa-IPV and Hib vaccine either separately or mixed did not alter the immunogenicity or reactogenicity profiles. Conclusion. DTPa-IPV vaccine, either separately or mixed with Hib vaccine, was at least as immunogenic and less reactogenic than the DTPw-Hib vaccine. Mixing DTPa-IPV and Hib vaccines did not alter the safety profile when compared with separate injections of both vaccines, A mixed DTPa-IPV-Hib Vaccine can be recommended for routine use as a booster dose in primed children.