BCG

The Bacillus Calmette–Guérin (BCG) vaccine is a vaccine primarily used to prevent tuberculosis (TB).

Tuberculosis kills or debilitates more adults aged 15 to 59 than any other disease in the world. TB is caused by Mycobacterium tuberculosis. Tuberculosis is an infectious disease that typically affects the lungs. Compared to other diseases caused by a single infectious agent, Tuberculosis is the second-leading cause of death worldwide. 

German microbiologist Robert Koch identified the microbial cause of tuberculosis in 1882. Following Koch’s discovery, the development of vaccines and effective drug treatments led to the belief that the disease had been all but eradicated. Indeed, the United Nations once estimated that tuberculosis (TB) would be eradicated worldwide by 2025. 
• TB symptoms (cough, fever, night sweats, weight loss, etc.) may be mild for months, and a person with TB can infect up to 10–15 other people through close contact over the course of a year
• TB is an airborne pathogen, which means that the bacteria that cause TB can spread through the air from person to person.

The primary use of The BCG vaccine is used to vaccinate against tuberculosis. The BCG vaccine can be administered intradermally after birth. BCG immunization generally causes some pain and scarring at the injection site. The main side effects are keloid—a large, raised scar.