Association between Bacillus Calmette-Guerin vaccination and type 1 diabetes in adolescence: A population-based birth cohort study in Quebec, Canada

Prev Med. 2022 Jan;154:106893. doi: 10.1016/j.ypmed.2021.106893. Epub 2021 Nov 17.


The Bacillus Calmette-Guerin (BCG) vaccine could reduce the incidence of type 1 diabetes through non-specific immunomodulation. Previous epidemiological studies, presenting some limitations, report no association. We examined this association of early life BCG vaccination and age at vaccination with type 1 diabetes incidence in adolescence in a large representative cohort in Quebec. The cohort included 387,704 individuals born in Quebec between 1970 and 1974 whose BCG vaccination status was determined from a provincial registry. Individuals were followed up from 1985 to their 19th birthday (maximum to 1993) for their use of physician services. Individuals were defined as type 1 diabetes cases if they had ≥4 related physician claims over a 2-year period, with at least 30 days between two claims. Cox proportional hazards regression was used to estimate the association of BCG vaccination and age at vaccination with type 1 diabetes. Covariates were selected based on a directed acyclic graph. Interaction according to sex was evaluated. A total of 178,133 (45.9%) individuals were vaccinated and 442 (0.11%) incident cases of type 1 diabetes were identified. The risk of type 1 diabetes was similar in vaccinated compared with unvaccinated individuals (adjusted hazard ratio = 1.06 [95% CI: 0.88-1.29]). There was no association with age at vaccination, and results did not differ by sex (Interaction, p = 0.60). Our results suggest that BCG vaccination does not prevent type 1 diabetes in adolescence.

Keywords: Administrative health data; Adolescence; Bacillus Calmette-Guerin vaccination; Population-based cohort study; Risk factor; Type 1 diabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • BCG Vaccine*
  • Birth Cohort
  • Cohort Studies
  • Diabetes Mellitus, Type 1* / epidemiology
  • Humans
  • Quebec / epidemiology
  • Vaccination / methods


  • BCG Vaccine