Evaluation of acellular DPT vaccines in infants

Two acellular DPT vaccines containing, as pertussis components, the genetically detoxified pertussis toxin mutant PT-9K/129G, either alone or combined with FHA and 69K, were evaluated for safety and immunogenicity in infants 8-14 months old. Both vaccines induced very mild local reactions which were consistent with the presence of alum and the previous administration of two doses of whole-cell DPT vaccine. A marked increase in specific antibodies to each pertussis component and in pertussis toxin neutralizing antibodies was observed after one dose of either acellular vaccines. All vaccinees also acquired an excellent protective immunity against diphtheria and tetanus, as assessed in vitro and in vivo