User:Mr. Ibrahem/BCG vaccine

Bacillus Calmette–Guérin (BCG) vaccine is a vaccine primarily used against tuberculosis (TB). In countries where tuberculosis or leprosy is common, one dose is recommended in healthy babies as close to the time of 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.

Rates of protection against tuberculosis infection vary widely and protection lasts up to twenty years. Among children it prevents about 20% from getting infected and among those who do get infected it protects half from developing disease. The vaccine is given by injection into the skin. There is no evidence that additional doses are beneficial.

Serious side effects are rare. Often there is redness, swelling, and mild pain at the site of injection. A small ulcer may also form with some scarring after healing. Side effects are more common and potentially more severe in those with poor immune function. It is not safe for use during pregnancy. The vaccine was originally developed from Mycobacterium bovis, which is commonly found in cows. While it has been weakened, it is still live.

The BCG vaccine was first used medically in 1921. It is on the World Health Organization's List of Essential Medicines. Between 2011 and 2014 the wholesale price was US$0.20 to US$1.10 a dose in the developing world. In the United States it costs US$100 to US$200. As of 2004 the vaccine is given to about 100 million children per year globally.