BCG vaccine (Bacillus Calmette-Guérin)

The BCG vaccine (Bacillus Calmette-Guérin) is a vaccine used primarily to protect against tuberculosis (TB), a serious bacterial infection that mainly affects the lungs. It contains a weakened version of the bacteria that causes TB, which helps the immune system recognize and fight the actual bacteria if exposed later. While it doesn't always prevent TB completely, especially in adults, it is effective at preventing severe forms like TB meningitis and miliary TB in children. The vaccine is widely used in countries with high TB prevalence and is administered as a small injection, usually during childhood.