Fact Sheets
BCG Vaccine
Last Updated: August 5, 1999
BCG, or bacille Calmette-Guérin, is a vaccine for
tuberculosis (TB) disease. BCG is used in many countries, but it
is not generally recommended in the United States because of the
low risk of infection with M. tuberculosis, the variable
effectiveness of the BCG vaccine against pulmonary TB, and the vaccines
interference with tuberculin reactivity.
BCG vaccination does appear to lower the risk of serious
complications of primary TB in children. But in the United States,
the consideration of BCG vaccination is recommended only for children
who have negative tuberculin skin test results, and who cannot be
given treatment for latent TB infection but are at high risk for
continuous exposure to infectious TB or to TB that is resistant
to isoniazid and rifampin. BCG is no longer recommended for health
care workers or other adults who are likely to be exposed to TB.
However, vaccination of health care workers should be considered
on an individual basis in settings in which (1) a high percentage
of TB patients are infected with M. tuberculosis strains
resistant to both isoniazid and rifampin, (2) transmission of such
drug-resistant M. tuberculosis strains to health care workers
and subsequent infection are likely, and (3) comprehensive TB infection-control
precautions have been implemented and have not been successful.
Furthermore, BCG should not be given to persons who are immunosuppressed,
such as persons who are infected with HIV. It should not be given
to pregnant women, even though no harmful effects of BCG vaccination
on the fetus have been observed.
Interpreting Tuberculin Skin Test Results in BCG-Vaccinated
Persons
In persons vaccinated with BCG, sensitivity to tuberculin
is highly variable, depending upon the strain of BCG used and the
group vaccinated. The presence or size of a postvaccination tuberculin
skin-test reaction does not predict whether BCG will provide any
protection against TB disease. Furthermore, the size of a tuberculin
skin-test reaction in a BCG-vaccinated person is not a factor in
determining whether the reaction is caused by M. tuberculosis
infection or the prior BCG vaccination.
Tuberculin skin testing is not contraindicated for
persons who have been vaccinated with BCG, and the skin-test results
of such persons are used to support or exclude the diagnosis of
M. tuberculosis infection. A diagnosis of M. tuberculosis
infection and the use of treatment of latent TB infection should
be considered for any BCG-vaccinated person who has a tuberculin
skin-test reaction of >=10 mm of induration, especially if any
of the following circumstances are present:
-
The vaccinated person is a contact of another
person who has infectious TB, particularly if the infectious
person has transmitted M. tuberculosis to others;
-
The vaccinated person was born or has resided
in a country in which the prevalence of TB is high; or
-
The vaccinated person (e.g., some health care
workers, employees and volunteers at homeless shelters, and
workers at drug-treatment centers) is exposed continually to
populations in which the prevalence of TB is high.
Treatment of latent TB infection should be considered
for BCG-vaccinated persons who are infected with HIV and who are
at risk for M. tuberculosis infection if they have a tuberculin
skin-test reaction of >= 5 mm induration.
BCG-vaccinated persons who have a positive reaction
to the tuberculin skin test, but who do not have TB disease, should
be evaluated for treatment of latent TB infection. The possibility
of TB disease should be considered for BCG-vaccinated persons who
have symptoms suggestive of TB.
For More Information
For more information about implementing CDC guidelines,
call your state health department.
To order the following publication, call the CDCs
Voice and Fax Information System (recording) toll free at (888)
232-3228, then press options 2, 5, 1, 2, 2 (Note: You may select
these options at any time without listening to the complete message).
Request the publication number of the document you would like to
order. You may also visit the Division of TB Eliminations
Web site at http://www.cdc.gov/nchstp/tb.
Publication # 00-5856. CDC. The role of BCG vaccine in the prevention
and control of tuberculosis in the United States. MMWR
1996;45(No.RR-4).
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