Incidence of Type 1 Diabetes in Relation to Exposure to Rotavirus Infections in Pre- and Postvaccine Birth Cohorts in Finland

To explore the incidence of type 1 diabetes in children in relation to exposure to rotavirus infections.A nationwide register-based ecological study on the 1995-2015 birth cohorts in Finland compared those born before and after the national implementation of the rotavirus vaccine in 2009.When the prevaccine 2001-2005 birth cohorts were compared with the postvaccine birth cohorts, the number of children exposed to rotavirus infection by the age of 5 years decreased from 2,522 per 100,000 children (2.5%) to 171 per 100,000 children (0.2%), while the incidence of type 1 diabetes in those aged <5 years decreased from 71.5 to 54.4 per 100,000 person-years (incidence rate ratio 0.79, 95% CI 0.71-0.86).At the population level, a decrease in exposure to rotavirus infections was associated with a decrease in the incidence of type 1 diabetes in young children.