Risk of Inflammatory Bowel Disease following Bacille Calmette-Guérin and Smallpox Vaccination: A Population-based Danish Case-Cohort Study.
BACKGROUND:: Childhood immunology has been suggested to play a role in development of inflammatory bowel disease (IBD) based on the studies of childhood vaccinations, infections, and treatment with antibiotics. Bacille Calmette-Guérin (BCG) and smallpox vaccinations were gradually phased-out in Denmark for children born between 1965 and 1976, hence allowing the study of subsequent risk of Crohn's