The Centre has placed an advance order for 30 crore doses of a vaccine being created by the Hyderabad-based Biological-E called Corbevax. Not only is it an indigenous vaccine, it also could potentially be the cheapest vaccine available in India when it finally launches. So, what makes Corbevax tick?
How Soon Will It Be Available?
The vaccine has received the nod for Phase III clinical trials in India after showing promising results in phases I and II. The Centre will pay Rs 1,500 crore for its consignment of 30 crore doses. Corbevax, like most other Covid-19 jabs out so far, is a two-dose vaccine.
After the completion of the Phase III trials, production to meet the Centre’s delivery target will continue between August and December.
The vaccine is reportedly going to be the cheapest vaccine available in India with the two shots expected to be cumulatively priced below Rs 400. In comparison, the Covishield vaccine which come at Rs 300-Rs 400 for a single dose. The Russian Sputik V, the third vaccine that has received emergency approval for use in India, costs around Rs 1,000.
Who Has Given Inputs For This Vaccine?
The Union health ministry said in a release that the government has extended substantial help to get this vaccine out. “The Department of Biotechnology has not only provided financial assistance in terms of grant-in-aid of over Rs 100 crore but has also partnered with Biological-E to conduct all animal challenge and assay studies through its Translational Health Science Technology Institute (THSTI), Faridabad," the health ministry stated.
Indian efforts to get this vaccine out builds on the work of the US-based Baylor College of Medicine, which had taken up research on this vaccine after the Sars outbreak of 2002. Biological-E licensed the technique from the original makers in August.
What Kind Of Vaccine Is It?
Corbevax is a recombinant protein subunit vaccine. It stands on the same platform as the hepatitis vaccine, so it is tried and tested, unlike the mRNA vaccines created by Pfizer and Moderna, which are the first of their kind to have been rolled out against any pathogen.
According to Gavi, The Vaccine Alliance, a global health partnership aimed at increasing access to immunisation in poor countries, “all vaccines work by exposing the body to molecules from the target pathogen to trigger an immune response — but the method of exposure varies".
So, while an mRNA vaccine inserts only the genetic code from the pathogen to trigger an immune response, a subunit vaccine achieves that effect by relying only on a part of the virus which, in this case, is its spike protein. The novel coronavirus uses the spike proteins, which also give it its name, to latch on to human cells.
Corbevax works by inserting only this spike protein from the virus into the human body with the goal of invoking an immune response. If you’re worried about the safety of this vaccine given it uses an actual portion of the virus, it has to be remembered that it is only using the spike protein and not the rest of the virus. Further, experts say that “because these fragments are incapable of causing disease, subunit vaccines are considered very safe". Protein subunit vaccines are already being used for hepatitis B and pertussis.
Because subunit vaccines use only a part of the virus, they may result in a weaker immune response and, hence, may require “adjuvants (agents that stimulate the immune system) and booster doses" to supplement the shot. Corbevax uses an adjuvant made by the US-based Dynavax.
Are These Vaccines Easy To Make?
Gavi says that such vaccines are “relatively cheap and easy to produce, and more stable than those containing whole viruses or bacteria".
Spelling out how the hepatitis B vaccine is made, Gavi says that once the genetic code for the protein subunit is isolated, it is inserted into yeast cells, which allow it to easily grow in large quantities. “The yeast is grown in large fermentation tanks, and then split open, allowing the antigen to be harvested. This purified protein is then added to other vaccine components, such as preservatives to keep it stable, and adjuvants to boost the immune response," Gavi says.