Childhood vaccination and type 1 diabetes

BACKGROUND: A link between childhood vaccinations and the development of type 1 diabetes has been proposed. METHODS: We evaluated a cohort comprising all children born in Denmark from January 1, 1990, through December 31, 2000, for whom detailed information on vaccinations and type 1 diabetes was available. Using Poisson regression models, we estimated rate ratios according to vaccination status, including the trend associated with the number of doses, among all children and in a subgroup of children who had siblings with type 1 diabetes. Given recent claims of clustering of cases of diabetes two to four years after vaccination, we also estimated rate ratios during the period after vaccination. RESULTS: Type 1 diabetes was diagnosed in 681 children during 4,720,517 person-years of follow-up. The rate ratio for type 1 diabetes among children who received at least one dose of vaccine, as compared with unvaccinated children, was 0.91 (95 percent confidence interval, 0.74 to 1.12) for Haemophilus influenzae type b vaccine; 1.02 (95 percent confidence interval, 0.75 to 1.37) for diphtheria, tetanus, and inactivated poliovirus vaccine; 0.96 (95 percent confidence interval, 0.71 to 1.30) for diphtheria, tetanus, acellular pertussis, and inactivated poliovirus vaccine; 1.06 (95 percent confidence interval, 0.80 to 1.40) for whole-cell pertussis vaccine; 1.14 (95 percent confidence interval, 0.90 to 1.45) for measles, mumps, and rubella vaccine; and 1.08 (95 percent confidence interval, 0.74 to 1.57) for oral poliovirus vaccine. The development of type 1 diabetes in genetically predisposed children (defined as those who had siblings with type 1 diabetes) was not significantly associated with vaccination. Furthermore, there was no evidence of any clustering of cases two to four years after vaccination with any vaccine. CONCLUSIONS: These results do not support a causal relation between childhood vaccination and type 1 diabetes.