What type of vaccine is Bacillus Calmette-Guerin (BCG)?

Bacillus Calmette-Guerin (BCG) is classified as a live bacteria vaccine. This vaccine is derived from a weakened strain of Mycobacterium bovis, which is a relative of the bacterium that causes tuberculosis (TB). The primary purpose of the BCG vaccine is to provide protection against tuberculosis, especially in individuals at high risk or in regions where TB is common.

Live bacteria vaccines, like BCG, stimulate a robust immune response because they closely mimic natural infection, allowing the body to develop immunity without causing the actual disease. This aspect makes live bacterial vaccines particularly effective in generating long-lasting immunity.

In contrast, other types of vaccines, such as inactivated viruses or subunit vaccines, utilize different methods to elicit an immune response. Inactivated virus vaccines contain viruses that have been killed or inactivated, while subunit vaccines consist of purified pieces of the pathogen, which do not replicate in the body. This distinction is crucial for understanding BCG's role in immunization against tuberculosis.