Rotavirus hospitalization and molecular epidemiology in northern Japan, 1987-1996.

Anticipating rotavirus vaccine in Japan, we examined long-term trends in rotavirus hospitalizations and characterized circulating strains. Rotavirus was detected in 974 children aged <5 years hospitalized for acute gastroenteritis in Akita between 1987 and 1996. The unadjusted incidence rate of rotavirus hospitalizations was 14.9 per 1000 child-years. In 9 out of 11 seasons G1P[8] was the most frequent genotype averaging 75%, but G2P[4] accounted for 87% of genotypes in 1 season. Interestingly, one strain found was the first and only G8P[4] reported in Japan. The burden of rotavirus hospitalization is substantial in Japan, and economic analysis may expedite vaccine introduction.