To the Editor I thank the authors for their interest in exploring the hypothesis of rotavirus vaccination and type 1 diabetes in children.1 In their study, 0.0475% of children who received the complete rotavirus vaccine series developed type 1 diabetes, and 0.0603% of children who did not receive the rotavirus vaccine developed type 1 diabetes (P = .006). This is similar to findings in several other large cohorts,2,3 indicating that the percentage of children who developed type 1 diabetes was lower in the group that was vaccinated (Table). This is in contrast to the findings in a smaller study, although type 1 diabetes status was unknown for 72.2% (14 968 of 20 732) of this cohort and these children were excluded.4,5