Clinical studies on efficacy and safety of acellular pertussis vaccine.

We conducted a retrospective survey of immunized school children in order to define the incidence of pertussis in relation to the acceptance rate of acellular pertussis vaccine combined with diphtheria and tetanus toxoid (ACP-DT vaccine). The attack rate of the disease was 0.01-0.02% in children with a history of recommended doses of the vaccine. In unimmunized children, 6.43-6.52% had a history of pertussis. To confirm the efficacy of the vaccine, a prospective household contact study based on clinical findings was conducted. Of 37 unimmunized children, 30 developed clinically diagnosed pertussis, and of 39 fully immunized children only two contracted the disease. Because there was no cluster of pertussis cases, a difference in vaccine efficacy between products seemed unlikely. From 1984 to 1987, there were no cases of high fever, encephalopathy, shock or death attributable to mass immunization with the vaccine. Severe erythema and swelling of the inoculated arm to the wrist were observed in 16 children (3.06/100,000 doses) after the third dose or after the booster dose. The vaccines used for these 16 children were from different manufacturers. All cases recovered completely.