Measles and measles vaccine in Japan.

Before the introduction of measles vaccine in 1971, measles was a common and well-recognized disease in Japanese children. Seroepidemiological studies conducted before the general use of the vaccine disclosed that measles epidemics differed from community to community; in rural areas, epidemics appeared at intervals of several years with the accumulation of susceptibles, and in urban areas, measles was endemic affecting younger children. The measles vaccines developed in Japan showed excellent safety and efficacy in the clinical trials for general use. Since 1978 measles vaccines have been routinely given to children aged 12 months or older, and incidence of measles decreased dramatically. However, the vaccine acceptance rate has been only as high as 85% to 90% and small-scale outbreaks of measles have been observed periodically among unimmunized children: Measles is far from being eradicated in Japan. This is primarily due to the insufficient vaccine acceptance rate, and more efforts towards mobilization of parents to have their children vaccinated are now in progress.