Vaccines

TB Vaccine (BCG)

Bacille Calmette-Guérin (BCG) is a vaccine for tuberculosis (TB) disease. This vaccine is not widely used in the United States, but it is often given to infants and small children in other countries where TB is common. BCG does not always protect people from getting TB.

BCG Recommendations

In the United States, BCG should be considered for only very select people who meet specific criteria and in consultation with a TB expert. Health care providers who are considering BCG vaccination for their patients are encouraged to discuss this intervention with the TB control program in their area.

Children

BCG vaccination should only be considered for children who have a negative TB test and who are continually exposed, and cannot be separated from adults who

• Are untreated or ineffectively treated for TB disease, and the child cannot be given long-term primary preventive treatment for TB infection; or
• Have TB disease caused by strains resistant to isoniazid and rifampin.

Health Care Workers

BCG vaccination of health care workers should be considered on an individual basis in settings in which

• A high percentage of TB patients are infected with TB strains resistant to both isoniazid and rifampin;
• There is ongoing transmission of drug-resistant TB strains to health care workers and subsequent infection is likely; or
• Comprehensive TB infection-control precautions have been implemented, but have not been successful.

Health care workers considered for BCG vaccination should be counseled regarding the risks and benefits associated with both BCG vaccination and treatment of latent TB infection.

Testing for TB in BCG-Vaccinated People

Many people born outside of the United States have been BCG-vaccinated.

People who were previously vaccinated with BCG may receive a TB skin test to test for TB infection. Vaccination with BCG may cause a positive reaction to a TB skin test. A positive reaction to a TB skin test may be due to the BCG vaccine itself or due to infection with TB bacteria.

TB blood tests (IGRAs), unlike the TB skin test, are not affected by prior BCG vaccination and are not expected to give a false-positive result in people who have received BCG.

For children under the age of five, the TB skin test is preferred over TB blood tests.

A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria. It does not tell whether the person has latent TB infection or has progressed to TB disease. Other tests, such as a chest x-ray and a sample of sputum, are needed to see whether the person has TB disease.

Learn about Testing and Diagnosis.