Experiences with acellular pertussis vaccine in Japan and epidemiology of pertussis

In 1975, with two successive cases of death shortly after whole cell pertussis vaccine, administration of pertussis vaccine was temporarily suspended. The vaccine was soon resumed, but setting the vaccination age at over two years for group vaccination. This caused the fall in pertussis vaccine acceptance rates until 1980, resulting in a nationwide epidemic of pertussis infection, with the peak of the epidemic in 1979. Acellular pertussis vaccine was developed and introduced in 1981, since then the coverage rate with the three-time pertussis vaccination have retained the levels of more than 80%. The number of cases of pertussis infection decreased steadily since 1980 and in 1985, the number of total pertussis patients was as low as those observed before 1974. However, incidence of pertussis patients aged less than 2 year remained higher. Dramatical decrease in side effects of pertussis vaccination was observed after the elevation of the age of the vaccination at mass immunization clinic to two years. Side effects has decreased further after the introduction of acellular pertussis vaccine.