Incidence of congenital rubella syndrome and influence of the rubella vaccination program for schoolgirls in Japan, 1981-1989.

In 1984, the authors first conducted a nationwide survey of deaf children with a history of maternal rubella (HMR) in special schools for the deaf in Japan. The survey showed that the incidence of congenital rubella syndrome in the Japanese mainlands was similar to those in the United States and Europe. In 1993, a second nationwide survey by the authors evaluated the efficacy of the vaccination program for schoolgirls begun in 1977. This second survey yielded 272 deaf children with HMR born between 1981 and 1989. Per 100,000 annual livebirths, the incidence rates were 1.56-9.95 in the epidemic years 1981-1982 and 1987-1988 and 0.20-0.72 in the interepidemic years. During the 1987-1988 epidemic, the incidence rates per 100,000 livebirths were 1.52 among mothers eligible for the vaccination program and 5.52-7.44 among mothers not eligible, and the difference was significant. However, only 21.7% of the women who delivered children during the 1987-1988 rubella epidemic were eligible for the vaccination program, and because the majority of deaf children with HMR were born to mothers not eligible, a decrease in the birth rate of deaf children with HMR was not observed. These data suggested the need to introduce a new vaccine program to suppress rubella epidemics.