title: Bacille Calmette-Guérin vaccination and incidence of IDDM in Montreal, Canada.
abstract: OBJECTIVE
  To describe the association between Bacille Calmette-Guérin (BCG) vaccination and IDDM development in two different case-control series (A and B) in Montreal.
  
  
  METHODS
  Case-control series A comprised 93 IDDM cases and 2,903 control subjects who participated in a community-based tuberculin reactivity survey and who belonged to the same birth cohorts and areas of residence as the IDDM cases, Case-control series B comprised 249 IDDM cases and 431 age- and sex-matched friends and neighborhood control subjects.
  
  
  RESULTS
  In series A, the BCG vaccination prevalence among cases and control subjects was 21.5% (95% CI 13.2-29.8%) and 22.3% (95% CI 20.8-23.8%), respectively. The odds ratio (OR) for IDDM associated with BCG vaccination was 1.09 (95% CI 0.62-1.91), after adjusting for the birth cohorts and areas of residence. The vaccination prevalence in series B was 17.7% (95% CI 13.0-22.4%) among cases and 15.1% (95% CI 11.7-18.5%) among control subjects. The OR for IDDM due to BCG vaccination was 1.26 (95% CI 0.79-2.02), taking into account the matched sets. Only one case (3.3%) from series B who had been vaccinated at birth was diagnosed by age 5, compared with 52 cases (24.5%) who had not been vaccinated (P < 0.01).
  
  
  CONCLUSIONS
  The lower proportion of birth-vaccinated IDDM cases diagnosed at a very young age, compared with nonvaccinated cases, possibly reflects a temporary boost of the immune functions after vaccination. However, as a whole, results from these analyses fail to support a protective role of BCG vaccination against juvenile-onset IDDM.
authors.affiliation: Epidemiology and Biostatistics Unit, Institut Armand-Frappier, Université du Québec, Laval, Canada. marie-elise_parent@iaf.uquebec.ca
authors.forename: M E
authors.initials: ME
authors.lastname: Parent
authors.forename: J
authors.initials: J
authors.lastname: Siemiatycki
authors.forename: R
authors.initials: R
authors.lastname: Menzies
authors.forename: L
authors.initials: L
authors.lastname: Fritschi
authors.forename: E
authors.initials: E
authors.lastname: Colle
mesh_terms: D000293:Adolescent; D001500:BCG Vaccine; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003710:Demography; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D016017:Odds Ratio; D015995:Prevalence; D011792:Quebec / Q000453:epidemiology; D012042:Registries; D014505:Urban Population; D014611:Vaccination / Q000706:statistics & numerical data*
chemical_list: D001500:BCG Vaccine