India moves towards providing precautionary doses of the Covid vaccine for its high-risk population healthcare workers, frontline workers and people over the age of 60 with comorbidities, there is a fresh set of vaccines that will soon become available for those who are yet to get their doses.
This week with approving vaccination for those in the 15-18 years age group, India also gave emergency-use authorisation to two other vaccines, Corbevax and Covovax.
Corbevax
Corbevax was develop by Hyderabad-base biopharmaceutical firm Biological E., the Baylor College of Medicine in the US, and US-base company Dynavax Technologies.
The Corbevax is what is known as a protein subunit vaccine.
Corbevax contains a protein of the coronavirus, and the body becomes prepare to recognise and launch an immune response against this.
This differs from vaccines like Covaxin, which contains the whole virus but in an inactivate form.
Corbevax contains the receptor binding domain, a region of the spike protein of the SARS-CoV-2 virus that helps it infect the host cell.
Corbevax uses a recombinant protein-base technology, a proven technology that has been in use since the 1980s and is use in the Hepatitis B vaccine.
This technology involves using genetic engineering to insert a DNA code that allows a harmless microbe, such as yeast, to grow the desired protein.
Researchers have use the yeast Pichia pastoris to grow the receptor binding domain of the SARS-CoV-2 virus.
The yeast does not cause a disease in humans, but the body learns to recognise the protein of the coronavirus.
If the body encounters the real virus in future, it will immediately recognise the receptor binding domain and launch an attack.
Corbevax contains only a part of the virus, it also needs an adjuvant, which is something adds to vaccines to make the immune response stronger.
As per the researchers, two Phase III clinical trials of Corbevax involving more than 3,000 people show that the vaccine is safe and effective, and that it has an efficacy of over 90%, although the results are yet to be publish in a peer-review journal.
Covovax
Covovax vaccine develop by US-base company Novavax will be produce by the Pune-base Serum Institute of India under the name Covovax.
As Covovax is also a recombinant protein-base vaccine.
To develop the vaccine, researchers select a part of the genetic sequence of the virus that produces the spike protein.
This sequence was then introduce in baculoviruses, pathogens that attack insects.
So, the difference from Corbevax is that instead of using yeast, this vaccine uses baculoviruses.
These modified baculoviruses were then made to infect moth cells in the lab, so that the cells produced proteins that are similar in structure to the SARS-CoV-2 spike protein.
These proteins were then purified and administer with an adjuvant called Matrix M.
Covovax tricks the immune system into believing that it is under attack from the real virus.
Phase III trials for the Novavax vaccine have been carry out in the UK, the US, Mexico and South Africa.
The results of Phase III trials among approximately 15,000 participants in the UK, publish in The New England Journal of Medicine on 23 September, found that the Novavax vaccine provided 89.7% protection against SARS-CoV-2 infection.
With these two new vaccines, India has also approve Molnupiravir, an antiviral that its makers say can treat people with mild and moderate Covid disease.
13 companies in India are set to manufacture this drug, including Cipla and Dr Reddy’s.
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