The BCG vaccine, or bacille Calmette-Guerin, is a vaccine used for tuberculosis disease. Many individuals who are born and live in countries where tuberculosis is rampant will have been vaccinated with the BCG in an effort to prevent childhood tuberculosis meningitis. However, BCG vaccine is not generally recommended for use in the United States because of the low risk of infection with the mycobacterium tuberculosis and the variable effectiveness of a vaccine against adult pulmonary TB.
Recent research has found that the BCG vaccine has been found to be only minimally effective against tuberculosis in children and not at all effective in preventing tuberculosis in adults. This is because the use of the BCG vaccine incorporates the mycobacterium bovis, the second bacteria which causes tuberculosis. The first bacteria, mycobacterium tuberculosis, is much more variable and has been found to use a different mechanism for infection than the mycobacterium bovis.
Researchers are now investigating methods of changing the infection mechanism of mycobacterium bovis in order to more significantly \”jumpstart\” the immune system to protect it against mycobacterium tuberculosis. Once perfected, the BCG vaccine will then be come a first line of defense against tuberculosis meningitis, a severe or form of meningitis which affects children and often leads to brain damage or death.
The BCG vaccination should be considered for children who have had a negative TB skin test but are continually exposed and cannot be separated from adults who either are untreated for a tuberculosis or have strains that are resistant to isoniazid and rifampin. Healthcare workers may be considered on an individual basis when they are working with a high percentage of patients who are infected with tuberculosis or there is ongoing transmission to healthcare workers or there is a comprehensive TB infection control precautions have been implemented but are not successful. Healthcare workers who may consider the BCG vaccine should be aware of the risks and benefits associated with the vaccination and the treatment for latent tuberculosis infection.
The BCG vaccine should not be given to individuals who are immunosuppressed, or pregnant. Individuals who have received the BCG vaccine will also have a false positive reaction to this TB skin test. This can complicate decisions about prescribing treatment if an individual is suspected to have tuberculosis or latent TB. There are however, blood tests to detect tuberculosis infections which are not affected by any prior vaccination and are less likely to give a false positive.
A new vaccine has been developed in Germany which has shown promising results in mice. However, researchers from the National Institute for Medical Research in London caution that developing another live vaccine based on the BCG may not address the problems that have been associated with conventional vaccinations. These issues will arise when using a live vaccine in individuals who suffer from HIV and AIDS.
Having an immune compromising illness or disease, such as HIV, increases the risk of developing tuberculosis, and the risk of developing multi-drug-resistant tuberculosis. The concern is that using a live vaccine in an individual who has HIV will cause more harm than good. Researchers who are developing this new \”souped up\” BCG vaccine state they are aware of the issue and that the new vaccine is not intended for use in immunocompromised patients. However, he was also quick to note that this new vaccine has been used safely in immune compromised mice.
RESOURCES
Center For Disease Control and Prevention: BCG Vaccine
World Health Organization: BCG Vaccine
Medline Plus: Bacillus Calmetter-Guerin Vaccine