Confused about COVID vaccines in India? This is for you

The Drugs Control General of India has permitted emergency use of Covid vaccine Sputnik V with certain conditions, clearing the way for a third vaccine in addition to Covishield and Covaxin.

Besides, the government on Tuesday also fast-tracked emergency approval for other jabs.

Here is what the vaccines are all about:

COVAXIN

Manufactured by Bharat Biotech in collaboration with the Indian Council of Medical Research and the National Institute of Virology, it uses an inactivated virus. It is developed by chemically treating novel coronavirus samples to make them incapable of reproduction.

Given as two doses four weeks apart, the therapeutic can be stored between 2-8 degrees Celsius. Preliminary data from its phase 3 trial shows the vaccine has an efficacy rate of 81 per cent.

COVISHIELD

Co-developed by the University of Oxford and British-Swedish company AstraZeneca and known as Covishield in India, the vaccine uses a viral vector, an engineered version of adenoviruses that infect chimpanzees to carry the gene responsible for the spike protein of the novel coronavirus.

It requires two doses given four weeks apart to produce the desired effects. The vaccine has an efficacy of 70 per cent after the first dose. Global clinical trials of the vaccine showed that when people were given a half dose and then a full dose, effectiveness hit 90 per cent. It can also be safely stored at 2-8 degrees Celsius.

SPUTNIK V

Sputnik V from Russia's Gamaleya Research Institute is the latest vaccine approved for emergency use in India. Sputnik V uses a cold-type virus vector. It is engineered to be harmless, as a carrier to deliver a small fragment of the coronavirus to the body. Safely exposing the body to a part of the virus's genetic code in this way allows it to recognize the threat and learn to fight it off, without the risk of becoming ill.

Sputnik V has been shown to have 92 per cent efficacy. It is given in two doses, three weeks apart. It can be stored at temperatures between 2-8 degrees Celsius.

POSSIBLY IN THE PIPELINE:

MODERNA

The mRNA vaccine by US-based company Moderna has been shown to have 94.1 per cent efficacy. In this type of vaccine, the messenger RNA -- or mRNA -- acts as a blueprint for the production of the coronavirus spike protein. The cells of the vaccine recipient use this mRNA segment to produce the viral protein to train the immune system for a future encounter with the infectious coronavirus.

Administered as two doses 28 days apart, the Moderna vaccine can be stored in the refrigerator at 2-8 degrees Celsius for up to 30 days. At -20 degrees Celsius it can be stored for up to six months.

PFIZER-BIONTECH

The US-backed Pfizer-Biontech's COVID-19 preventive, like the Moderna vaccine, is based on the segments of the genetic material of the novel coronavirus. Preliminary data from the clinical trials showed that two doses of the vaccine given three weeks apart provided efficacy of 94 per cent.

One limitation for the Pfizer vaccine has been its requirement for ultracold storage -- up to -70 degrees Celsius.

JOHNSON & JOHNSON

The adenovirus vectored vaccine by the American company is provided as a single dose. The company had noted that the therapeutic can be stored for up to three months when refrigerated at 2-8 degrees Celsius, and up to two years when frozen at -20 degrees Celsius. The overall efficacy of the J&J vaccine was found to be 66 per cent globally, and 72 per cent in the US.