Tuberculosis Vaccine

Bacille Calmette-Guérin (BCG) is a vaccine for tuberculosis (TB) disease. The vaccine is not generally used in the United States

Many people born outside the United States have been vaccinated with BCG. It is given to infants and small children in countries where TB is common. It protects children from getting severe forms of active TB disease, such as TB meningitis. The vaccine's protection weakens over time.

How does it work?

The BCG vaccine works through a two-part mechanism involving both trained immunity and adaptive immunity. First, it provides broad, non-specific protection by inducing "trained immunity" in innate immune cells through epigenetic reprogramming and metabolic changes. Second, it creates a specific immune response against Mycobacterium tuberculosis by developing antigen-specific memory T cells.

Why isn’t it used in the US?

The BCG vaccine is not routinely used in the U.S. because the risk of tuberculosis (TB) infection is low, the vaccine's effectiveness against adult pulmonary TB is variable, and it can interfere with the interpretation of the TB skin test. Instead, the U.S. follows a selective strategy, using the vaccine only for specific, high-risk individuals and relying on other testing methods, like TB blood tests, to detect infections.  

Common questions

Can I have inactive TB or TB disease even if I have received the TB vaccine?

• Yes, a person can have or get TB even if they received the TB vaccine (BCG). The BCG TB vaccine does not always protect people from getting TB. Contact your health care provider if you think you or someone in your family has been exposed to TB germs.

Should people who received the BCG TB vaccine get a TB blood test or TB skin test?

• TB blood tests are the preferred tests for people who have received the BCG TB vaccine. The vaccine can cause a false positive TB skin test reaction. Unlike the TB skin test, TB blood tests are not affected by BCG vaccination.

Is the BCG vaccine used for other diseases and conditions?

• Yes, the BCG vaccine is used for other diseases and conditions beyond tuberculosis prevention. It is a standard treatment for non-muscle-invasive bladder cancer and has been studied for its potential in treating various other diseases, including other mycobacterial infections, certain viral infections, and some immunologic diseases like multiple sclerosis and type 1 diabetes. 
  • Cancer immunotherapy: BCG is the gold standard for immunotherapy for certain types of bladder cancer, as it helps the immune system fight cancer cells. It is also being researched for other cancers.
  • Other infections: It can protect against other non-tuberculous mycobacterial infections, such as leprosy and Buruli ulcer.  
  • Immunologic diseases: BCG's ability to stimulate the immune system has led to its investigation for use in treating autoimmune diseases like multiple sclerosis and type 1 diabetes.

Click here for more information about the BCG Vaccine from the CDC.