Rotarix in Japan: Expectations and Concerns

Abstract

A live-attenuated, orally-administered,monovalent, human rotavirus vaccine, Rotarix®\r(GlaxoSmithKline Biologicals, Rixensart,Belgium), was licensed and launched in 2011 asthe first rotavirus vaccine in Japan. The rotavirus causes a substantial disease burden with an estimated 790,000 outpatient visits, 27,000-\r78,000 hospitalizations, and approximately 10 deaths each year in Japan. Since a recent clinical trial showed that Rotarix was as\refficacious in Japan as in other industrialized countries, it is expected that the annual number\rof rotavirus hospitalizations will be reduced to between 1000-3000, and that outpatient visits will be reduced to 200,000. The universal\rrotavirus immunization program with Rotarix was calculated to be at the threshold of being cost-effective, even from the healthcare perspective, and it was highly cost-effective from the societal perspective, assuming that\rRotarix is co-administered with other childhood vaccines. While Rotarix contains only a single G1P[8] human rotavirus, the postlicensure studies in Brazil showed that Rotarix provided\ra 75%-85% protective efficacy against severe dehydrating diarrhea or hospitalizations due to fully-heterotypic G2P[4] strains. While\rpostlicensure studies detected a small and finite risk of intussusception associated with\rthe administration of Rotarix, the authors conclude that Rotarix is safe to administer to\rinfants between 6-12 weeks of age for the first dose and by 24 weeks of age for the second dose. However, the authors strongly discourage the delayed administration of the first dose\rbetween 13-20 weeks of age, which is allowed without any warning. Given the high incidence of naturally-occurring intussusception in Japan (185 cases per 100,000 children/year among children less than 1 year of age), this should\rprevent pediatricians and parents from having ill-perceptions of Rotarix being associated with\ran increased number of temporally-associatedintussusception, and fully appreciate the benefit\rof the rotavirus vaccine.