Bacille Calmette Guerin (BCG) is a type of vaccine used to protect against tuberculosis (TB). The vaccine is made from a weakened strain of Mycobacterium bovis, a bacterium closely related to the bacterium that causes TB in humans.
The BCG vaccine is primarily used in countries with high rates of TB, especially in infants and young children. The vaccine is given as a single injection in the upper arm, and provides protection against severe forms of TB, such as TB meningitis and miliary TB.
While the BCG vaccine is generally safe, it can cause some side effects, such as swelling and redness at the injection site, fever, and swollen glands. In rare cases, serious side effects can occur, such as abscesses or infections at the injection site, or disseminated BCG infection in people with weakened immune systems.
In some countries, the BCG vaccine is also used as a treatment for bladder cancer. The vaccine is injected directly into the bladder, where it can stimulate the immune system to attack and destroy cancer cells.
Despite its widespread use, the effectiveness of the BCG vaccine is somewhat controversial. While it is generally effective at preventing severe forms of TB in children, its effectiveness in adults is less clear. Additionally, the vaccine can interfere with TB skin testing, making it difficult to accurately diagnose TB infection in vaccinated individuals.
Overall, the BCG vaccine remains an important tool in the fight against TB, particularly in countries with high rates of the disease. However, its limitations and potential side effects should be carefully considered when making decisions about its use.