Long-term efficacy of BCG vaccine in American Indians and Alaska Natives: A 60-year follow-up study

JAMA. 2004 May 5;291(17):2086-91. doi: 10.1001/jama.291.17.2086.


Context: The duration of protection from tuberculosis of BCG vaccines is not known.

Objective: To determine the long-term duration of protection of a BCG vaccine that was previously found to be efficacious.

Design: Retrospective record review using Indian Health Service records, tuberculosis registries, death certificates, and supplemental interviews with trial participants.

Setting and participants: Follow-up for the period 1948-1998 among American Indians and Alaska Natives who participated in a placebo-controlled BCG vaccine trial during 1935-1938 and who were still at risk of developing tuberculosis. Data from 1483 participants in the BCG vaccine group and 1309 in the placebo group were analyzed.

Main outcome measures: Efficacy of BCG vaccine, calculated for each 10-year interval using a Cox regression model with time-dependent variables based on tuberculosis events occurring after December 31, 1947 (end of prospective case finding).

Results: The overall incidence of tuberculosis was 66 and 138 cases per 100 000 person-years in the BCG vaccine and placebo groups, respectively, for an estimate of vaccine efficacy of 52% (95% confidence interval, 27%-69%). Adjustments for age at vaccination, tribe, subsequent BCG vaccination, chronic medical illness, isoniazid use, and bacille Calmette-Guérin strain did not substantially affect vaccine efficacy. There was slight but not statistically significant waning of the efficacy of BCG vaccination over time, greater among men than women.

Conclusion: In this trial, BCG vaccine efficacy persisted for 50 to 60 years, suggesting that a single dose of an effective BCG vaccine can have a long duration of protection.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • BCG Vaccine* / immunology
  • Controlled Clinical Trials as Topic
  • Female
  • Follow-Up Studies
  • Humans
  • Indians, North American*
  • Inuit
  • Male
  • Middle Aged
  • Proportional Hazards Models
  • Treatment Outcome
  • Tuberculosis / epidemiology
  • Tuberculosis / ethnology
  • Tuberculosis / prevention & control*
  • Vaccination


  • BCG Vaccine