title: Childhood vaccination and type 1 diabetes.
abstract: 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.
authors.affiliation: Danish Epidemiology Science Centre, Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark. aii@ssi.dk
authors.forename: Anders
authors.initials: A
authors.lastname: Hviid
authors.forename: Michael
authors.initials: M
authors.lastname: Stellfeld
authors.forename: Jan
authors.initials: J
authors.lastname: Wohlfahrt
authors.forename: Mads
authors.initials: M
authors.lastname: Melbye
mesh_terms: D001724:Birth Weight; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D003718:Denmark; D003922:Diabetes Mellitus, Type 1 / Q000209:etiology* / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008423:Maternal Age; D016012:Poisson Distribution; D012042:Registries; D035781:Siblings; D014611:Vaccination / Q000009:adverse effects*