title: The effectiveness of BCG vaccination in preventing Mycobacterium tuberculosis infection and disease in Greenland.
abstract: BACKGROUND
  The BCG vaccine's ability to prevent Mycobacterium tuberculosis infection (MTI) remains highly debated. In Greenland, BCG vaccination was introduced in 1955, but was temporarily discontinued (1991-1996) due to nationwide policy changes. The study aimed to use the transient stop in BCG vaccination to evaluate the effect of vaccination on MTI prevalence and TB incidence.
  
  
  METHODS
  MTI study: A cross-sectional study (2012), comprising East Greenlanders born during 1982-2006, evaluated the effect of BCG vaccination on MTI prevalence; a positive interferon γ release assay defined an MTI case. Associations were estimated using logistic regression. TB study: a cohort study covering the same birth cohorts with follow-up until 2012 evaluated the vaccine's effect on TB incidence. A personal identifier allowed for follow-up in the TB notification system. Associations were estimated using Cox regression.
  
  
  RESULTS
  MTI study: Included 953 participants; 81% were BCG-vaccinated; 29% had MTI, 23% among vaccinated and 57% among non-vaccinated. BCG vaccination reduced the odds of MTI, OR 0.52 (95% CI 0.32 to 0.85), p=0.01. Vaccine effectiveness against MTI was 20%. TB study: Included 1697 participants followed for 21,148 person-years. 6% were notified with TB, 4% among vaccinated and 11% among non-vaccinated. BCG vaccination reduced the risk of TB, HR 0.50 (95% CI 0.26 to 0.95), p=0.03, yielding a vaccine effectiveness of 50%.
  
  
  CONCLUSIONS
  BCG vaccination was effective in reducing both MTI and TB disease among children and young adults in a TB high-endemic setting in Greenland.
authors: Department of Epidemiology Research, Statens Serum Institut, Copenhagen S, Denmark.
authors: S W
authors: http://orcid.org/0000-0002-6499-8581
authors: SW
authors: Michelsen
authors: Department of Epidemiology Research, Statens Serum Institut, Copenhagen S, Denmark.
authors: B
authors: B
authors: Soborg
authors: Department of Epidemiology Research, Statens Serum Institut, Copenhagen S, Denmark.
authors: A
authors: A
authors: Koch
authors: Department of Epidemiology Research, Statens Serum Institut, Copenhagen S, Denmark.
authors: L
authors: L
authors: Carstensen
authors: Department of Infectious Disease Immunology, Statens Serum Institut, Copenhagen S, Denmark.
authors: S T
authors: ST
authors: Hoff
authors: Department of Infectious Disease Immunology, Statens Serum Institut, Copenhagen S, Denmark.
authors: E M
authors: EM
authors: Agger
authors: International Reference Laboratory of Mycobacteriology, Statens Serum Institut, Copenhagen S, Denmark.
authors: T
authors: T
authors: Lillebaek
authors: The Tasiilaq District Hospital, Tasiilaq, Greenland.
authors: H C F
authors: HC
authors: Sorensen
authors: Department of Epidemiology Research, Statens Serum Institut, Copenhagen S, Denmark.
authors: J
authors: J
authors: Wohlfahrt
authors: Department of Epidemiology Research, Statens Serum Institut, Copenhagen S, Denmark.
authors: M
authors: M
authors: Melbye
mesh_terms: D000276:Adjuvants, Immunologic; D000293:Adolescent; D000328:Adult; D001500:BCG Vaccine; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006116:Greenland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D059425:Interferon-gamma Release Tests; D008297:Male; D009169:Mycobacterium tuberculosis; D015995:Prevalence; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control*; D055815:Young Adult
chemical_list: D000276:Adjuvants, Immunologic; D001500:BCG Vaccine
keywords: Clinical Epidemiology; Infection Control; Tuberculosis