Protective efficacy of the Takeda acellular pertussis vaccine combined with diphtheria and tetanus toxoids following household exposure of Japanese children

Abstract

The clinical efficacy of an acellular pertussis vaccine containing lymphocytosis-promoting factor, filamentous hemagglutinin, agglutinogens, and the 69-kd outer membrane protein, combined with diphtheria and tetanus toxoids and adsorbed onto an aluminum salt, was assessed in a household contact study. The occurrence of pertussis 7 to 30 days following home exposure among 62 previously vaccinated children was compared with that among 62 unvaccinated children similarly exposed. Classic whooping cough was diagnosed in 43 unimmunized children, and 1 vaccinated child experienced a 5-week illness that was probably pertussis (efficacy, 98%; 95% confidence interval, 84% to 99%). A few children in each group incurred respiratory illnesses that may have represented mild, atypical pertussis; including these as probable pertussis, vaccine efficacy was 81% (95% confidence interval, 64% to 90%). It is concluded that prior immunization with this four-component pertussis vaccine combined with diphtheria and tetanus toxoids is highly efficacious in preventing pertussis.