Coronavirus: The complete list of COVID vaccines currently in use in India

Vaccines are so far the best protection against COVID-19 along with precautionary practices like wearing masks, keeping hands sanitised and physical distancing. "But it’s not vaccines that will stop the pandemic, it’s vaccination," says the World Health Organsation (WHO) thus emphasizing on the need for mass vaccination.

In India, more than 75% adults have been completely vaccinated against COVID-19, government data says.

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Vaccines contain weakened pathogens or inactive parts of the pathogen that upon entering the body trigger immune response. This prepares the body and prompts the immune system to react in the same way it would when the real pathogen enters the body.

Vaccines are sometimes given in multiple doses, like in many COVID-19 vaccines, to develop memory cells in the body for a longer duration.

In other words, vaccines prepare the body to fight against foreign agents by building up a memory of the foreign agent and by training the immune system to work against it.

There are three main approaches to developing a vaccine: one is where the entire pathogen is used in inactivated form, the second is where just the part of the pathogen that triggers immune response is used and the third is where the genetic material of the pathogen is used

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Apart from the active part of the pathogen, the vaccines also contain several other ingredients which are essential to facilitate immune response and are safe for human usage.

Vaccines have preservatives which protects the vaccines from being contaminated. Usually one-dose vials do not have preservatives as they are used in a single time on a single human being. Vaccines which are used to vaccinate more than one person have preservatives in them. 2-phenoxyethanol is a commonly used preservative in vaccines. This chemical is not toxic to human beings.

Adjuvants are added to some vaccines to improve the immune response. These are also called immunopotentiators. Aluminium salts (like aluminium phosphate, aluminium hydroxide or potassium aluminium sulphate) are usually used as adjuvants.

Surfactants are also used in order to keep the vaccines together instead of clumping of particles.

Sterile water or diluent is also used in vaccines to bring the concentration of vaccine to optimum level for use.

Sugars, gelatins and proteins are used to stabilize the vaccine and prevent chemical reactions from happening and keep the vaccine from sticking to the vial.

Various companies have come forward to make vaccines against COVID-19 pandemic. The Pfizer/BioNTech vaccine was the first to receive emergency validation from WHO in December 2020. By May 2021, vaccines developed by Astrazeneca-SK Bio, Serum Institute of India, Janssen and Moderna vaccines were also approved by the WHO for emergency use.

In India, COVAXIN, COVISHIELD and Sputnik vaccines are being administered to people. While two vaccines– Covishield (AstraZeneca's vaccine manufactured by Serum Institute of India) and Covaxin (manufactured by Bharat Biotech Limited)--were granted emergency use authorization by the Central Drugs Standard Control Organization (CDSCO) in India. Sputnik - V was granted emergency use authorization in April 2021.

Homemade vaccine, COVAXIN, is a whole-virion inactivated coronavirus vaccine which is also used to manufacture vaccines like Influenza, Rabies and Hepatitis- A. It is manufactured by Bharat Biotech.

COVISHIELD is a viral vector-based technology which is also used to manufacture Ebola vaccines. It is manufactured by the Serum Institute of India. This is based on the same patent technology as the Astrazeneca vaccine.

Sputnik vaccine is developed by Moscow's Gamaleya Institute. It is based on well-studied human adenovirus vector platform. The safety, efficacy and lack of long-term adverse effects of adenovirus vaccines have been proven in more than 250 clinical trials over two decades, says an official statement.

In December 2021, the WHO approved emergency use listing for Covovax vaccine produced by the Serum Institute of India. Covovax was assessed under its emergency use listing procedure based on the review of data on quality, safety and efficacy, a risk management plan, programmatic suitability, and manufacturing site inspections carried out by Drug Controller General of India (DCGI).

ZyCoV-D is the world’s first DNA based vaccine for COVID-19 developed by India. It has been developed in partnership with the Department of Biotechnology under the ‘Mission COVID Suraksha’ and implemented by BIRAC. On August 20, 2021 it had received approval for emergency use authorization from the Drug Controller General of India (DCGI). It is a DNA plasmid-based COVID-19 vaccine which produces a spike protein of the coronavirus in the cell and this elicits an immune response against the coronavirus.

India is also looking forward to its first indigenous messenger or mRNA vaccine which is currently in the last leg of phase 3 clinical trials. This vaccine has been developed by Gennova Biopharmaceuticals. In this case the messenger RNAs trigger an immune response in our bodies which in turn produces antibodies and thus protects us from the infection.