TB Vaccine (BCG) What You Should Know

Tuberculosis (TB) is a life-threatening disease that can be spread from person to person.

In many parts of the world, a vaccine called BCG (Bacillus Calmette-Guérin) is often given to infants and small children to give them some protection against TB.

People who have been vaccinated with BCG can develop TB.

BCG is not widely used in the United States because it does not always protect against TB.

If you were vaccinated with BCG, you may test "positive" on a TB skin test. This may be due to BCG vaccine, OR to a real TB infection. The TB skin test cannot tell the difference.

A positive skin test, even in a person who has been vaccinated with BCG, usually means latent TB infection.

Latent TB infection means TB germs are living in your body, but you are not sick and cannot spread TB to others. People with latent TB infection can become sick with active TB disease. In the United States, a person who has had a BCG vaccine and who tests positive on a TB skin test, may be offered treatment that will prevent latent TB infection from developing into active TB disease.

A TB blood test, known as an Interferon Gamma Release Assay, is not affected by the BCG vaccine. A "positive" TB blood test means you have latent TB infection.

Remember, BCG does not give life long protection.

TB can kill. Getting a test for latent TB infection and getting treatment can save your life.

If you have questions, talk to your health care provider or contact your local health department.