Last Updated: April 2006
BCG, or bacille Calmette-Guérin, is a vaccine for tuberculosis
(TB) disease. 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, 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.
Children. BCG vaccination should only be considered for children
who have a negative tuberculin skin test 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 long-term 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 drug-resistant M. tuberculosis
strains to health care workers and subsequent infection is likely;
- 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).
Immunosuppressed Persons. 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).
Pregnant Women. 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
Testing for TB in BCG-Vaccinated Persons
Many foreign-born persons have been BCG-vaccinated. BCG vaccination
may cause a positive reaction to the tuberculin skin test (TST),
which may complicate decisions about prescribing treatment. Despite
this potential for BCG to interfere with test results, the TST and
the QuantiFERON®-TB Gold test (QFT-G) are not contraindicated
for persons who have been vaccinated with BCG. The presence or size
of a TST reaction in these persons 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
Treatment for LTBI in BCG-Vaccinated 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 ≥5 mm of induration:
- 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-a antagonists)
In addition, persons in the following high-risk groups should be
considered for treatment of LTBI if their reaction to the TST is
≥ 10 mm of induration:
- Recent arrivals (<5 years) from high-prevalence 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 <4 years of age, or children and adolescents exposed
to adults in high-risk categories
Persons with no known risk factors for TB may be considered for
treatment of LTBI if their reaction to the tuberculin test is ≥15
mm of induration. However, 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.
of new vaccines for tuberculosis: recommendations of the Advisory
Council for the Elimination of Tuberculosis (ACET). MMWR
1998; 47 (No. RR-13).
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
Health Organization. Issues Relating to the Use of BCG in Immunization
Programmes-A Discussion Document (PDF) (1999).