Explained: What makes Biological E's Corbevax Covid-19 vaccine different

The government announced at the start of the month that it would buy 30 crore doses of local firm Biological E's Covid-19 vaccine Corbevax. While many of the vaccines approved across the world fall under the mRNA (Pfizer), inactivated virus (Covaxin), or viral vector category (Covishield), Corbevax falls under a different category and is the first of its kind.

Corbevax is a “recombinant protein sub-unit” vaccine, meaning that it is made using a part of the coronavirus, specifically, its spike protein. The spike protein is what allows the coronavirus to enter our body's cells, replicate them, and cause the disease. When given on its own, however, the spike protein is not at all harmful.

As is the case in any other vaccine, the spike protein, when injected, allows the body's immune cells to develop an immune response to it and is thereby ready to tackle the virus in any future event of infection.

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Although this method of producing a vaccine has been previously used for the Hepatitis-B shot, Corbevax, along with Novavax are among the first Covid-19 vaccines to come under the recombinant protein sub-unit category.

The vaccine is currently in stage 3 of clinical trials, which is slated to end in July.

The Hyderabad-based firm's vaccine's difference doesn't end there though. Corbevax is also poised to be one of most affordable vaccines available in India should it be given an emergency use authorisation. According to an Indian Express report this is a result of the way it is produced.

While Biological E is tasked with producing the vaccine for India and possibly the world, its origins lie on the other side of the planet at the Baylor College of Medicine’s National School of Tropical Medicine in the US. The institute transferred its production cell bank to Biological E in August last year.

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Over the past decade, the school had been working on developing such vaccines for SARS and MERS. Dr Peter Hotez, Professor and Dean at the School, told the publication that the process of producing a recombinant protein sub-unit is similar to the production of beer.

He said that after sequencing the spike protein's gene, it is put in yeast for cloning and releasing copies of the protein. "Instead of releasing alcohol, in this case, the yeast is releasing the recombinant protein,” told the Indian Express.

The ingredients used to make the vaccine are readily available, which is what makes it much cheaper than an already available mRNA or inactivated virus vaccine.

For India, which suffered in the last two months terribly because of a second wave of the Covid-19 pandemic and shortage of vaccines, among other crucial medical supplies, an affordable vaccine like Corbevax could be a much-needed addition to its arsenal. That, however, depends on whether, the vaccine, which is in the middle of its stage 3 clinical trial, is given a stamp of approval by the regulators.