National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention

Division of Tuberculosis Elimination

CS227840_B

TB Elimination

BCG Vaccine

Introduction

BCG, or bacille Calmette-Guérin, is a vaccine for 

tuberculosis (TB) disease. Many foreign-born 

persons have been BCG-vaccinated. BCG is used 

in many countries with a high prevalence of TB 

to prevent childhood tuberculous meningitis 

and miliary disease. However, BCG is not 

generally recommended for use in the United 

States because of the low risk of infection with 

Mycobacterium tuberculosis (M. tuberculosis), 

the variable effectiveness of the vaccine against 

adult pulmonary TB, and the vaccine’s potential 

interference with tuberculin skin test reactivity. 

The BCG vaccine should be considered only for 

very select persons who meet specific criteria 

and in consultation with a TB expert.

Recommendations

Children. BCG vaccination should only be 

considered for children who have a negative 

tuberculin skin test (TST) and who are 

continually exposed, and cannot be separated 

from, adults who

• Are untreated or ineffectively treated for TB 

disease (if the child cannot be given longterm treatment for infection); or 

• Have TB 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 M. tuberculosis strains resistant to both 

isoniazid and rifampin; 

• There is ongoing transmission of such drugresistant M. tuberculosis 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 

(LTBI).

Contraindications

Immunosuppression. BCG vaccination 

should not be given to persons who are 

immunosuppressed (e.g., persons who are 

HIV infected) or who are likely to become 

immunocompromised (e.g., persons who are 

candidates for organ transplant).

Pregnancy. BCG vaccination should not be 

given during pregnancy. Even though no harmful 

effects of BCG vaccination on the fetus have been 

observed, further studies are needed to prove

its safety.

Testing for TB in BCG-Vaccinated 

Persons

The TST and TB blood tests to detect TB infection 

are not contraindicated for persons who have been 

vaccinated with BCG.

TST. BCG vaccination may cause a false-positive 

reaction to the TST, which may complicate 

decisions about prescribing treatment. The 

presence or size of a TST reaction in persons who 

have been vaccinated with BCG does not predict 

whether BCG will provide any protection against 

TB disease. Furthermore, the size of a TST reaction 

in a BCG-vaccinated person is not a factor in 

determining whether the reaction is caused by 

LTBI or the prior BCG vaccination. (See below for 

specific guidance on skin test results.)

TB Blood Tests. Blood tests to detect TB infection, 

unlike the TST, are not affected by prior BCG 

vaccination and are less likely to give a falsepositive result.

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Treatment for LTBI in BCGVaccinated Persons

Treatment of LTBI substantially reduces the risk 

that TB infection will progress to disease. Careful 

assessment to rule out the possibility of TB 

disease is necessary before treatment for LTBI is 

started. Evaluation of TST reactions in persons 

vaccinated with BCG should be interpreted using 

the same criteria for those not BCG-vaccinated. 

Persons in the following high-risk groups should 

be given treatment for LTBI if their reaction to the 

TST is at least 5 mm of induration or they have a 

positive result using a TB blood test:

• HIV-infected persons 

• Recent contacts to a TB case 

• Persons with fibrotic changes on chest 

radiograph consistent with old TB 

• Patients with organ transplants 

• Persons who are immunosuppressed for 

other reasons (e.g., taking the equivalent of 

>15 mg/day of prednisone for 1 month or 

longer, taking TNF-α antagonists)

In addition, persons in the following high-risk 

groups should be considered for treatment of 

LTBI if their reaction to the TST is at least 10 mm of 

induration or they have a positive result using a 

TB blood test:

• Recent arrivals (less than 5 years) from highprevalence countries 

• Injection drug users 

• Residents and employees of high-risk 

congregate settings (e.g., correctional 

facilities, nursing homes, homeless shelters, 

hospitals, and other health care facilities) 

• Mycobacteriology laboratory personnel 

• Persons with clinical conditions that place 

them at high-risk for developing TB disease 

(e.g., diabetes)

• Children less than 4 years of age, or children 

and adolescents exposed to adults in highrisk categories

Persons with no known risk factors for TB may be 

considered for treatment of LTBI if their reaction to 

the tuberculin test is at least 15 mm of induration 

or they have a positive result using a TB blood 

test. Targeted skin testing programs should only 

be conducted among high-risk groups. All testing 

activities should be accompanied by a plan for 

follow-up care for persons with TB infection or 

disease.

Additional Information

1. CDC. Development of new vaccines for 

tuberculosis: recommendations of the 

Advisory Council for the Elimination of 

Tuberculosis (ACET). MMWR 1998; 47 (No. 

RR-13). http://www.cdc.gov/mmwr/preview/

mmwrhtml/00054407.htm

2. CDC. The role of BCG vaccine in the 

prevention and control of tuberculosis 

in the United States: a joint statement by 

ACET and the Advisory Committee on 

Immunization Practices . MMWR 1996; 45 (No. 

RR-4). http://www.cdc.gov/mmwr/preview/

mmwrhtml/00041047.htm 

3. World Health Organization. Issues Relating 

to the Use of BCG in Immunization 

Programmes-A Discussion Document (1999). 

http://www.who.int/vaccines-documents/

DocsPDF99/www9943.pdf

4. CDC. Interferon-Gamma Release Assays 

(IGRAs) - Blood Tests for TB Infection. MMWR

2010; 59 (No.RR-5). http://www.cdc.gov/tb/

publications/factsheets/testing/IGRA.htm

http://www.cdc.gov/tb

October 2011