Bacille Calmette-Guérin (BCG)

BCG, or bacille Calmette-Guérin, is a vaccine for TB. BCG is used in many countries with a high prevalence of TB to prevent childhood tuberculous meningitis and miliary disease. However, BCG is not generally recommended for use in the United States because of the low risk of infection with Mycobacterium tuberculosis, the variable effectiveness of the vaccine against adult pulmonary TB, and the vaccine's potential interference with tuberculin skin test reactivity.

TSTs and TB blood tests to detect TB infection are not contraindicated for persons who have been vaccinated with BCG. Evaluation of TST reactions in persons vaccinated with BCG should be interpreted using the same criteria for those not BCG-vaccinated.

Unlike the TST, TB blood tests do not detect the presence of BCG and are less likely to give a false-positive result.

• BCG Vaccine
  Fact sheet from the CDC that presents the basics about BCG.