It is one of the most widely administered vaccines in the world. In use for nearly a century, it has been given to over a billion people. And yet, it is still not good enough. The bacillus Calmette-Guerin vaccine, or BCG, is a live but weakened bacterium that is about 80% effective at protecting young healthy children from severe forms of tuberculosis (TB) - particularly tuberculous meningitis, which affects the brain, and miliary TB, a systemic infection of the body. But BCG offers little protection to adolescents and young adults from the form of the disease that spreads widely and causes most deaths: pulmonary TB. Moreover, BCG is a replicating bacterium; in children infected with HIV the vaccine itself can cause disease, known as BCG-osis.
展开▼
