Sputnik V, Covaxin And Covishield: How do these COVID vaccines work?

At a time, when the whole country is grappling with the sudden spike in COVID-19, India is on its way to get its third vaccine against the deadly virus after Bharat Biotech’s Covaxin and Oxford-AstraZeneca’s Covishield. The Drug Controller of India has recently granted permission for the restricted emergency of Sputnik V, a Russian vaccine. It was the first COVID-19 vaccine registered for public use last year. Here is what every student should know about these three vaccines.   

Sputnik V
Sputnik V, named after the world’s first artificial satellite made by Russia, is a combination of two adenoviruses (Ad26 and Ad5), the ones that cause common cold, flu and other respiratory infections. Scientists have used the weakened versions of this virus for the vaccine and genetically modified them by infusing a protein of the novel coronavirus in them. When administered to the human body, these adenoviruses do not multiply but stimulate the immune cells to work against COVID-19 infection. Sputnik V is approved for usage in 60 countries now including India. Media reports suggest that this COVID-19 vaccine is going to be available in India between late April and June. 

Covishield 
The functioning of Covishield is similar to that of Sputnik V. Like the Russian vaccine, it is also made up of a weak strain of   adenovirus. In this case, the virus is derived from chimpanzees. Modified with the genes of a particular protein of the novel coronavirus, this vaccine enables human immune cells to fight against COVID-19 infection. However, it is unable to infect the human body. Covishield is developed by Oxford University in collaboration with a Swedish multinational company AstraZeneca and manufactured by the Serum Institute of India (SII), Pune. Two doses of the vaccine are administered at a gap of 6 weeks.  

Covaxin
This COVID-19 vaccine is developed by Hyderabad-based pharma company Bharat Biotech, Indian Council of Medical Research (ICMR) and the National Institute of Virology (NIV), Pune. Unlike Covishield and Sputnik V, Covaxin is composed of an inactivated strain of the novel coronavirus which doesn’t replicate inside human cells. It simply alerts the immune system and stimulates antibodies to protect against this deadly infection. This technology has been used in a wide range of vaccines for seasonal influenza, polio, pertussis, rabies, and Japanese Encephalitis.