Maximising the boost: On mixing COVID-19 vaccines

India must test the feasibility of mixing vaccines to help enable informed choice

Updated - December 30, 2021 08:31 am IST

Published - December 30, 2021 12:02 am IST

Heralding a new frontier in India’s vaccination programme, the apex drug regulator has approved two more vaccines under emergency use authorisation (EUA), and an antiviral drug . Corbevax, by Biological-E, is a protein sub-unit vaccine as is Covovax, to be made by the Serum Institute of India. Both, however, differ in their manufacturing process . Covovax has already been approved by WHO under its Emergency Use Listing and will be available globally as part of the COVAX initiative to ensure that at least 40% of the world is vaccinated on priority. Molnupiravir, which was approved this month by the U.S. Food and Drug Administration, on the heels of Paxlovid by Pfizer Inc., is said to be a promising drug for those with mild and moderate disease and easily administered as a pill — its key selling point. Thirteen companies in India are set to make this drug . It has been approved for use under EUA for treating adults with COVID-19 “who have high risk of progression to disease”. Having more vaccines in the arsenal bodes well because of the uncertainties that the pandemic brings about. As of today, 90% of India’s adults have been inoculated with one dose and 60% with both doses.

The experience with the new variant Omicron is that it is so infectious, it does not discriminate among the vaccinated and the unvaccinated, though severe disease and death is disproportionately among the latter. Here too, those who are above 40 years continue to be the most vulnerable. Despite three vaccines being available, India has overwhelmingly been reliant on Covishield and that is a matter of concern as a new chapter in the vaccination programme unfolds. The new directives say that “precaution doses”, which are third doses of the vaccines an individual has already been inoculated with, will be available for health-care and frontline workers and those above 60 with comorbidities. The 15-17 year age group will get only Covaxin from January 3. That several Indians have been exposed to a live infection in the second wave only improves the odds of protection. However, the only study on mixing Covaxin and Covishield — that resulted from a mix-up in Uttar Pradesh — showed that antibody levels were higher than two doses of either vaccine. A combination of Novavax and AstraZeneca (Covishield) was also effective in boosting antibodies, according to the COV-BOOST study in the United Kingdom. India’s top medical institutions must immediately test the feasibility of mixing all available vaccines so that these may be made quickly available if needed giving recipients the option of an informed choice. The second wave revealed a treatment fiasco with remdesivir — sans any therapeutic merit — that saw irrational demand and black marketing. While molnupiravir has many more manufacturers, it is important to ensure against hoarding or indiscriminate use given its potential side-effects.

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