Vaccination of children in Japan

The coverage rates of six vaccines (BCG, polio, DPT, measles, mumps and varicella) and the prevalence of these diseases in Japan were investigated. It was found that 82.2% of children had been inoculated with BCG before their first birthday, and 85.4% were given two doses of polio vaccine before their second birthday. The high acceptance rates of these vaccines seem to be attributable to mass inoculations at health centers. On the other hand, the median age when the first dose of DPT vaccine was given was as late as 22 months. Mass administration of this vaccine during infancy should be performed since about one-quarter of the patients with diphtheria, pertussis or tetanus were less than one year old. The cumulative percentage for measles inoculation failed to reach 60% by the second birthday. Considering that the incidence of measles has not yet been satisfactory lowered and that infants under 23 months of age account for about one-half of this incidence, more children less than 18 months old should be immunized. The ineffective rate of varicella vaccine was found to be 18.2%, although reestimation of its effectiveness may be necessary.