BCG vaccine: 100 years and counting

BCG works well in some geographic locations and not so well in others

The centenary celebrations of the discovery of insulin have eclipsed another seminal event in the history of medicine that has had significant impact on human health - the first use of BCG (Bacillus Calmette-Guerin), the vaccine against tuberculosis (TB) in humans. TB is caused by a bacterium called Mycobacterium tuberculosis, belonging to the Mycobacteriaceae family consisting of about 200 members. Some of these cause diseases like TB and leprosy in humans and others infect a wide range of animals. Mycobacteria are also widely dispersed in the environment. In humans, TB most commonly affects the lungs (pulmonary TB), but it can also affect other organs (extra-pulmonary TB). TB is a very ancient disease and has been documented to have existed in Egypt as early as 3000 BC. Sadly, unlike other historically dreaded diseases like smallpox, leprosy, plague and cholera that have been either eradicated or controlled to a large extent due to advances in science and technology, TB continues to be a major public health problem in the world. According to the WHO’s Global TB Report, 10 million people developed TB in 2019 with 1.4 million deaths. India accounts for 27% of these cases.