A BCG vaccine is given to prevent tuberculosis (TB) infection. The
vaccine contains bacteria called BCG (bacille Calmette-Guérin) that is closely
related to the bacteria that cause TB.
The BCG vaccine is often given to people in countries where TB is
common, such as South America, Africa, Asia, Eastern Europe, and Russia. But it
is seldom used in the United States because:
- TB is not a widespread problem in the U.S.
effectiveness of the vaccine varies. It is most effective at preventing TB from
spreading outside of the lungs (extrapulmonary TB) in children.
vaccine interferes with TB skin test results. People who get a BCG vaccination
are likely to have TB skin test results that show they have a TB infection even
when they aren't infected.