BCG vaccine: 100 years and counting

BCG vaccine: 100 years and counting

Part of: GS Prelims and GS-3: Science 

Context: The centenary celebrations of the first use of BCG (Bacillus Calmette-Guerin), the vaccine against tuberculosis (TB) in humans.

About TB

• TB is caused by a bacterium called Mycobacterium tuberculosis, belonging to the Mycobacteriaceae family consisting of about 200 members. 
• In humans, TB most commonly affects the lungs (pulmonary TB), but it can also affect other organs (extra-pulmonary TB).
• Despite being avery ancient diseases (existed in Egypt in 3000BC), it has not been eradicated or controlled to a large extent.
• According to the WHO’s Global TB Report, 10 million people developed TB in 2019 with 1.4 million deaths. India accounts for 27% of these cases.

About BCG (Bacillus Calmette-Guerin)

• BCG was developed by two Frenchmen, Albert Calmette and Camille Guerin.
• They modified a strain of Mycobacterium bovis (that causes TB in cattle) till it lost its capacity to cause disease while retaining its property to stimulate the immune system. It was first used in humans in 1921.
• In addition to its primary use as a vaccine against TB, BCG also protects against respiratory and bacterial infections of the newborns, and other mycobacterial diseases like leprosy and Buruli’s ulcer. 
• In India, BCG was first introduced in a limited scale in 1948 and became a part of the National TB Control Programme in 1962.
• One intriguing fact about BCG is that it works well in some geographic locations and not so well in others. Generally, the farther a country is from the equator, the higher is the efficacy. 
  • It has a high efficacy in the UK, Norway, Sweden and Denmark; and little or no efficacy in countries on or near the equator like India, Kenya and Malawi, where the burden of TB is higher.
• Currently, BCG is the only licensed vaccine available for the prevention of TB. 
• Over the last ten years 14 new vaccines have been developed for TB and are in clinical trials.

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