Hindustan Times ST (Jaipur)

Covaxin jab effective against Covid-19 variants: ICMR study

- Anonna Dutt

NEW DELHI: The indigenous­ly developed Covaxin vaccine is effective against variants of the SARS-COV-2 virus that causes Covid-19, including the delta variant that was first sequenced in India, a study by the Indian Council of Medical Research has found.

The research, which is yet to be peer reviewed, also discovered that the vaccine is thrice as effective in creating antibodies as a previous Covid infection. To be sure, other research has shown that a previous infection does confer stronger immunity . titres with BBV152 (Covaxin) sera against B.1.351 (beta) and B.1.617.2 (delta), its neutralisa­tion potential is well establishe­d. Lastly, the broad epitope (large number of binding sites) coverage of an inactivate­d vaccine decreases the magnitude of reduced neutralisa­tion against emerging variants,” the study concluded.

Dr Pragya Yadav, senior scientist at the National Institute of Virology-pune and the lead author of the paper, said, “Although there is a minor reduction in the neutralisa­tion titre, it (Covaxin) will still be able to protect the vaccinated individual and eventually lessen the severity of the disease.”

Epidemiolo­gist and vaccine expert Dr Chandrakan­t Lahariya said the antibody titres are not predictive of the efficacy of a vaccine. “Even if the antibody level is 1, the person is thought to be seroconver­ted and protected from the infection. That is what the researcher­s have shown: despite the reduction in antibody titres, the vaccine works,” he said.

Lahariya said that one likely impact of the lower titres could be that the antibodies might diminish sooner. “But, with Covid-19, protection against the virus is complex. Studies have shown that even after the decline in antibody levels, there is T-cell immunity. A study from the University of Washington has said that this immunity might be life-long for those who had mild infection.”

Covaxin, which was developed by Bharat Biotech in associatio­n with ICMR, is one of the three vaccines that have so far been approved for Covid-19 immunisati­on in India, the other two being Covishield made by Serum Institute of India and Sputnik V of Russia.

Covaxin uses an inactivate­d whole virus to elicit an immune response.

Covaxin accounts for at least 11% of the vaccine shots given in the country so far, according to data on the government’s COWIN platform. The company is in the process of scaling up its production, including by licensing its technology, and is likely to contribute a higher share of immunisati­on in the future.

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