What Does the TB Vaccination Do?

Tuberculosis, or TB, is a contagious disease caused by the bacteria Mycobacterium tuberculosis. TB mainly affects the lungs, although it sometimes attacks other parts of the body as well. According to the Aeras Global TB Vaccine Foundation, 1.7 million people die from tuberculosis each year. There is currently only one TB vaccine: the Bacille Calmette-Guerin (BCG) vaccine, which has been in use since 1921.

• The tuberculosis vaccine is most effective in children.

Protects Children

• According to the Aeras Global TB Vaccine Foundation, the TB vaccine is most effective in reducing the number of cases of severe tuberculosis in children. For this reason, the tuberculosis vaccine is often given to children living in countries with large populations of TB-infected people, as the CDC explains. Children in the United States receive the TB vaccine only under very select circumstances.

Offers Limited Protection for Adults

• As the Aeras Global TB Vaccine Foundation explains, the TB vaccine is unreliable in preventing adult pulmonary TB, the most common type of TB around the world. According to the National Network for Immunization Information, one large study suggested that TB vaccination protected about 50% of recipients from tuberculosis of the lungs; other studies have drawn varying conclusions. Assessing effectiveness is complicated by the fact that, as the World Health Organization points out, the TB vaccines stored and administered throughout the world are no longer genetically identical and thus may differ in effectiveness.

May Confuse Skin Test Results

• According to the CDC, TB vaccination can confuse the results of a tuberculin skin test, one of the methods that health care providers use to screen for tuberculosis. In some patients, prior vaccination can produce positive skin test results even when the patient does not actually have tuberculosis. Tuberculosis blood tests, however, are not affected by TB vaccination.

May Cause Side Effects

• According to the National Network for Immunization Information, TB vaccination can cause side effects in some recipients. The most frequent side effect is inflammation or soreness at the injection site; rarely, the TB vaccine may cause swelling in certain lymph nodes or may lead to the formation of a pustule or ulcer at the injection site.

May Endanger Immunosuppressed Patients

• According to the World Health Organization, there has recently been concern that the TB vaccine could lead to tuberculosis infection in people with weakened immune systems, such as those infected with HIV. The CDC recommends that the TB vaccine not be administered to people who are immunosuppressed or immunocompromised.