Coronavirus | A vaccine is a vaccine... regulators never approve a backup, says virologist Shahid JameelRead Now
Shahid Jameel, Virologist, and Director, Trivedi School of Biosciences, Ashoka University said different concerns existed regarding both approved vaccines in India adding that it was premature to assume they would be useful against the 'UK strain'.
We've seen two Indian vaccines approved. Covishield by Serum Insitute of India has submitted — but not published — any data on its Indian trial. Bharat Biotech has published safety and immunogenicity data (preprint) for Covaxin but hasn't generated the all important efficacy data. Do you think the regulator has made a judicious call in approving both?
As more details trickle out, it appears that the fear of a second wave, propelled by more contagious viruses of the B.1.1.7 lineage (popularly called UK variant), weighed heavily on the Drug Controller General of India (DCGI) and the regulatory committees. Since what was presented by the companies to them is not available in the public domain, it is hard to second guess.
Could you explain the relative merits of a DNA vaccine, RNA vaccine vs the tried and tested inactivated virus-platforms? Are the latter vestigial technology like typewriters? Are the new kinds of vaccines inherently easier to make or more effective?
I would not call inactivated viral vaccines as vestigial. Most effective vaccines in use today belong to that category. The inherent difficulty with this platform is that it requires viruses to be grown to high titres. That is often difficult and sometimes not possible. Take for example the hepatitis E virus on which I worked for three decades. It grows very poorly in culture and thus no inactivated vaccine has been possible.
Nucleic acid vaccines are a new platform and would be used for the first time with Covid vaccines. So far the results for mRNA vaccines look good and DNA vaccines are yet to be tested. But the long term safety for both is yet to be established. These would be platforms for the future simply because it is much easier to manufacture RNA and DNA than proteins. Viral protein antigens are best made by the body to ensure proper conformation and structure, which is often not possible in vitro. DNA, RNA and viral vectors (eg adenoviruses) use the cell’s machinery to make viral protein antigens.
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