Maximising the boost: On mixing COVID-19 vaccines

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

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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