On 6^th August, India gave Emergency Use Authorization for Johnson and Johnson’s single-dose COVID-19 vaccine, expanding its vaccine basket, which now has five vaccines — Covishield, Covaxin, Sputnik V, Moderna’s, and Johnson & Johnson’s vectored vaccine (JNJ-78436735 or Ad26.COV2.S ). One of the many new vaccines that India is waiting to introduce in its mammoth vaccination drive, this particular one was developed by Janssen Pharmaceutica, a Belgium-based division of the company, in collaboration with Beth Israel Deaconess Medical Center of Boston. The vaccine can be stored at normal temperature for three months, which makes it easily transportable to rural and remote parts of the country.

The vaccine, say its makers, has been found to be 85% effective against severe or critical disease and has demonstrated protection against hospitalisation and death. It is also apparently 66.3% effective in clinical trials (efficacy) at preventing laboratory-confirmed COVID-19 infection in people who had shown no evidence of being previously infected.

It also works against a range of Sars-CoV-2 variants of concern, including against Delta (B.1.617.2), Beta (B.1.351) and Gamma (P.1), say its makers.

Read more: “Vaccines will help those who get it, as well as those who can’t”

India has administered over 50 crore doses of Covid-19 vaccines so far, primarily using Covishield and Covaxin. Russia’s Gamaleya Institute’s Sputnik V had joined the vaccination program a month back.

Covishield and Sputnik V are both vectored vaccines that target the SARS-Cov-2 spike. Covishield uses an adenovirus that causes the common cold in Chimpanzees, while Sputnik uses adenoviruses that cause common cold in humans but uses a different adenovirus for the two doses. India had received its first batch of 125 million doses of the Sputnik vaccine in May.

The Russian Direct Investment Fund (RDIF) has collaborated with five domestic vaccine manufacturers — Gland Pharma, Hetero Biopharma, Stelis Biopharma, Virchow Biotech and Morepen — to produce over 750 million doses annually.

The role of any vaccine, be it a killed vaccine, vectored, attenuated, subunit, or mRNA (see explainer below), is to prepare the body’s immune system to protect the body against future COVID-19 infection. Mild initial side-effects of a vaccine like local pain and fever for a couple of days are common, but not universal.

New vaccine candidates

Broadly speaking, to vaccinate 90 crore adults, India needs about 180 crore doses of vaccines, which means it will soon need to add more vaccines to its basket. The government says that it would not be a problem as India will have many more vaccines available for use by the end of 2021.

The first of these in the pipeline is Ahmedabad-based pharmaceutical company Cadila-Zydus’s ZyCoV-D, a plasmid DNA vaccine which, when injected, produces the spike protein of the SARS-CoV-2 virus, eliciting an immune response mediated by the cellular and humoral arms of the immune system. ZyCoV-D, a three-dose, intradermal vaccine, can be stored at 2-8 degrees Celsius but has also shown good stability at 25 degrees Celsius for around three months.

The company has applied for emergency use authorisation. Clinical studies for this vaccine were carried out at more than 50 sites across the country. Its makers claim that the vaccine is efficacious against the new mutant strains, especially the Delta variant. And is also safe for children in the 12-18 age group.

Next in line could be Covovax, developed by US pharmaceutical giant Novavax. Pune-based Serum Institute will produce two billion doses of this vaccine.

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This vaccine’s clinical trials are likely to conclude by November, but SII has applied for licence on the basis of global trial data. Given in two doses, Covovax has shown about 91% efficacy in trials in the US among volunteers at high risk of severe infection. The vaccine is also said to be 100% effective in preventing moderate to severe cases.

Another vaccine which will be a part of India’s immunisation drive is an mRNA vaccine HGC019 developed by Gennova and HDT Biotech Corporation. The vaccine is expected to get Emergency Use Approval by October. The target antigen in this vaccine is delivered in the form of a self-replicating mRNA of the virus.

Generally, in vaccines, viral proteins known to cause infection and disease are used to stimulate the body’s immune response against the pathogen. The vaccine’s genetic material i.e., its mRNA and DNA instruct the host cells to produce viral antigens in the body that in turn stimulate both humoral (antibody) and cellular (T-cells) protective immune response in case of infection.

The genetic advantage

One of the most talked-about benefits of mRNA vaccines studied before for flu, Zika, rabies and cytomegalovirus (CMV) is that these can be rapidly developed and modified quickly for any new variant. Gennova has conducted animal toxicity studies and finished Phase 1 clinical trials on its vaccine candidate in the US and India. It is now gearing up for the Phase II/III clinical study.

Another major vaccine candidate expected to enter the Indian market is Biological E’s Corbevax, a recombinant protein sub-unit vaccine. This is similar to Covovax vaccine mentioned earlier. The vaccine is made up of the spike protein present on the surface of SARS-Cov-2, which helps the virus gain entry into the human cell and cause infection.

The Indian government has placed orders for 300 million doses of this still under-trial vaccine, developed in collaboration with US-based Dynavax and Baylor College of Medicine. The vaccine has reportedly shown promising results in the first two trial phases.

Besides, the nasal vaccine of Bharat Biotech is also expected to be ready for use this year. This is also an adeno-vectored vaccine like the J&J vaccine but is instilled/sprayed into the nose – the entry point of the SARS-COV-2 virus. Vaccine experts feel that since this is not injectable, it will be easy to administer to a large population in a short time.

Other vaccines such as Pfizer’s, Moderna’s and the second vaccine from Johnson and Johnson are also in the pipeline but there is no confirmation on their arrival in India yet. Manufacturers of these international vaccines have reportedly demanded an indemnity bond that will exempt them from liability claims in case of adverse effects. According to the Ministry of Health and Family Welfare (MOHFW), a team of central government officials are in dialogue with these companies to resolve these issues.

Know your vaccine

Also read:

• Third wave of the pandemic: Is Bengaluru prepared?
• COVID vaccines: Citizens need better communication and information