ACELLULAR PERTUSSIS VACCINES DEVELOPED IN JAPAN AND THEIR APPLICATIONFOR DISEASE-CONTROL

Acellular pertussis vaccines, comprising mainly pertussis toxin and fi lamentous hemagglutinin (FHA) and used successfully in Japan since 198 1, were evaluated, Anti-pertussis toxin antibody responses in children immunized with acellular pertussis vaccines were comparable or higher than in convalescent-stage patients with pertussis, while those for a nti-FHA were far higher. Reactogenicity was much less than with whole cell pertussis vaccines: Fever greater than or equal to 38 degrees C o ccurred in 2%-4% of vaccinees; there was little redness greater than o r equal to 5 cm in diameter at the vaccination site with the first dos e hut occurred in 7%-8% of vaccinees with subsequent doses. The estima ted efficacy of acellular pertussis vaccine in children ages 2-8 years was 84% (95% confidence interval, 71%-91%), Since vaccine-induced imm unity weakens after 6-10 years, adults are now a major source of pertu ssis transmission. The source of infection was an adult in 11.2% (10/8 9) of cases, and the secondary attack rate was 10.3% (19/185). Immuniz ation with acellular pertussis vaccines for both adults and children i s recommended for disease control.