BCG is a vaccine that is used for the treatment of tuberculosis. One dose of BCG is given through injection as early as possible after the birth. This vaccine is widely used in countries where tuberculosis (TB) is common, for instance India, Pakistan, Sri Lanka, Thailand, Japan, Hong Kong, South Korea, Singapore etc.
- Full form of BCG is Bacillus Calmette–Guérin.
- BCG is prepared from a strain of the weakened (but still alive) bovine tuberculosis bacillus, Mycobacterium bovis. This bacteria causes tuberculosis in cattle. To prepare BCG, this bacteria is weakened to an extent that it loses the ability to cause tuberculosis in humans.
- In humans, Mycobacterium tuberculosis bacteria is the causative agent of tuberculosis. Robert Koch was the first person to isolate Mycobacterium bovis from Mycobacterium tuberculosis.
- BCG was discovered by Albert Calmette, a French physician and bacteriologist, and his colleague, Camille Guérin, a veterinarian.
- Both Albert Calmette and Camille Guérin repeatedly subcultured the Mycobacterium bovis 239 times over a period of 13 years. With each subculture the virulence of bacteria got reduced. Finally they were able to isolate sufficiently weakened bacteria that it would not cause tuberculosis in lab animals.
- BCG was first used in humans in 1921. The vaccine was named after its inventors.
- The vaccine is administered through an injection in the skin.
- BCG injection leaves a raised scar at the site where needle enters the skin. This scar is often used as a proof that the BCG injection was administered to the person.
- In addition to tuberculosis, BCG has also been found effective in treatment of bladder cancer. BCG has been one of the most successful immunotherapies.
- Protection induced by BCG lasts up to 20 years.
- BCG is listed on the World Health Organization’s List of Essential Medicines.
- A 1994 systematic review found that BCG reduces the risk of getting TB by about 50%.
Why BCG has been in News Lately?
During the coronavirus pandemic, it was observed that there were significantly lesser number of Covid-19 cases in countries where BCG vaccine has been in wide use. For example, despite having huge populations and hygiene issues, countries like India and Pakistan did not register proportionately as high as the United States, United Kingdom, Spain, France etc.