Explanation & Key Takeaways: Bacillus Calmette–Guérin (BCG) vaccine: • B.C.G. vaccine is a vaccine primarily used against tuberculosis (TB). • It is named after its inventors Albert Calmette and Camille Guérin. • In countries where tuberculosis or leprosy is common, one dose is recommended in healthy babies as soon after birth as possible. • In areas where tuberculosis is not common, only children at high risk are typically immunized, while suspected cases of tuberculosis are individually tested for and treated • Adults who do not have tuberculosis and have not been previously immunized but are frequently exposed may be immunized as well. • BCG also has some effectiveness against Buruli ulcer infection and other nontuberculous mycobacteria infections. • Additionally, it is sometimes used as part of the treatment of bladder cancer. • The BCG vaccine was first used medically in 1921. • It is on the World Health Organization's List of Essential Medicines. • As of 2004, the vaccine is given to about 100 million children per year globally. Hence, the B.C.G. vaccine prevents Tuberculosis or T.B.