Dr. Greene’s Answer:
Tuberculosis has been aptly called the “Captain of the Men of Death.” It remains the most important infectious disease in the world in terms of human suffering and death. Evidence of tuberculosis has been found in the earliest human remains, from Neanderthal skeletons to Egyptian mummies. As the planet became progressively more crowded, this contagious disease became even more of a problem.
A History of the BCG Vaccine
A vaccine that could safely and effectively prevent tuberculosis would be a tremendous gift to humanity. In 1908, Calmette and Guerin at the Institut Pasteur in Paris began working with slow-growing mycobacteria that produced tuberculosis in cattle. They selected the less virulent organisms, and 231 generations later they had a very mild strain that, when used as a vaccine, can greatly increase resistance to tuberculosis. It produces a mild infection that is effective at preventing the serious disseminated (diseminada) and miliary (miliar) forms of the disease. [These are not specific strains of TB, but the names given when TB runs rampantly through the bloodstream or organs of the entire body.] The BCG vaccine (the Bacillus of Calmette and Guerin) was first given in 1921, and is currently used in more than 100 countries (Red Book 2012).
BCG Vaccine Safety
Although mild infection is part of this vaccine, serious reactions are quite rare. The incidence of fatal reactions is 2 per million vaccinations with infants tending to be at higher risk. Most (but not all) of these occur in children with an underlying immunodeficiency (Red Book 2012). Overall, the BCG vaccine is one of the safest vaccines in use.
Research has shown that the BCG vaccine is most effective at preventing serious tuberculosis infections outside of the lungs. It is not as effective at preventing the more common tuberculosis infections of the lung.
Who Should Get the BCG Vaccine? Who Should Not?
People who benefit the most from BCG are those who are exposed to it most frequently. In light of this fact, BCG is indicated for infants, children, or adults who either:
- live in area where infection rates of tuberculosis exceed 0.1% per year (WHO 2004)
- are at high risk for prolonged exposure to infected adults who are untreated
- or who are continuously exposed to adults with resistant TB
The BCG vaccine should not be given to individuals who either:
- have known or suspected HIV infection (in most cases)
- have congenital or acquired immunodeficiency
- are on immunosuppressants, such as high-dose corticosteroids
- have leukemia or lymphoma
- or who have a history of radiation exposure
- have current burns or skin infections
- are currently pregnant
While the BCG vaccine is by no means a perfect solution, it has prevented untold misery and death. Used in the right setting, it is an excellent vaccine.