Vaccine News Daily (12.18.2013)
Vaccine News Daily reported on a study of the effectiveness of the bacille Calmette-Guérin (BCG) vaccine against pulmonary TB, the most common form of the disease. BCG, the only licensed TB vaccine, is administered to children in many countries as part of their routine childhood immunizations. The prevailing belief is that the vaccine is effective against extrapulmonary TB and only sometimes effective against pulmonary TB based on location. Researchers from the London School of Hygiene & Tropical Medicine conducted a review of global studies on all reported BCG trials to determine whether the vaccine was effective against pulmonary TB as well as extrapulmonary TB.
Findings indicated that BCG was very effective against pulmonary TB worldwide. The researchers learned that the vaccine’s reputation for not being effective was because exposure to prior infection reduced its efficacy. According to Punam Mangtani, lead author of the study, the research corrected the belief that BCG had little effect against pulmonary TB and emphasized its value in controlling the major burden of the disease. Mangtani stated that the knowledge that previous infection affected the vaccine’s efficacy meant that the vaccine should be administered early, if possible immediately after birth.
The researchers concluded that BCG proved to have a much higher efficacy against pulmonary TB when administered to individuals with no previous TB history; hence, individuals must receive new BCG-based vaccines before they acquire the infection.
The full report, “Protection by BCG Against Tuberculosis: A Systematic Review of Randomised Controlled Trials,” was published online in the journal Clinical Infectious Diseases (2013; doi: 10.1093/cid/cit790).