Efficacy of acellular pertussis vaccine in Japan--comparison of two areas, one area where immunization started at 6 months and the other area at over 2 years of age--Regional Surveillance Committee on Tuberculosis and Infectious Diseases of Osaka.

In the Osaka area, a very satisfactory surveillance system of infectious diseases has been achieved with the establishment of a weekly facsimile network, and computer aided graphics and feedback system. A mathematical formula has been devised for calculating the number of reported cases in exactly 100,000 of the population using the constant reported number of cases of exanthema subitum every week. With this method, we compared the incidence of pertussis patients in two areas, one where acellular pertussis vaccine is given to children after 6 months of age and the other where it is given at more than 2 years of age. The former area has the one fifth the incidence of pertussis patients of the latter.