Bharat Biotech’s Covaxin works against Delta Plus variant, new study finds

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Bharat Biotech’s Covaxin is effective against the Delta Plus variant of the coronavirus despite slightly reduced neutralisation antibody titres, a new study by Indian Council of Medical Research-National Institute of Virology has found. The study has also found the vaccine to be effective against the Delta and the B.1.617.3 variants.

The Delta variant has already been classified by the World Health Organization (WHO) as a variant of concern. Apart from triggering India’s second Covid-19 wave during March-May — it is estimated to have caused 90% of the cases India reported — the variant has been found in nearly 99 countries. More infectious than the Alpha, Beta, and Gamma variants, it is the leading cause of breakthrough infections in vaccinated individuals across the globe.

The Delta variant has recently mutated into the Delta AY.1, AY.2, and AY.3 variants. The AY.1 (Delta Plus), a highly infectious variant first detected in April in India, has subsequently been detected in 20 other countries.

However, its prevalence is relatively low, according to genome sequencing by INSACOG (Indian SARS-CoV-2 Genomics Consortium), which has found 70 such cases in India.

At present, there is no information on the efficacy of the vaccines available against the variant. It is also not clear if the variant has a higher transmissibility, causes severe disease, and evades immune response when compared to the Delta variant.

The likelihood that the variant can escape immune response has put ongoing vaccination programmes at risk. Research suggests that the Delta Plus variant contains in its spike protein an additional mutation (K417N). According to emerging evidence, this mutation could resist monoclonal antibodies.

Indian Council of Medical Research’s Head of Epidemiology and Communicable Diseases Dr. Samiran Panda told The Indian Express that Covaxin could neutralise the Delta, Delta Plus, and the B.1.617.3 variants. According to the sera of vaccines in Covid-naïve, recovered with full vaccination, and breakthrough cases, 1.3, 2.5, and 1.9-fold reduction against the Delta variant was witnessed when compared to the B.1 variant, respectively, the study found.

According to lead author Dr. Pragya Yadav, they observed a minor reduction in the neutralising antibody titre in recovered, post-immunised infected, and fully vaccinated cases when compared to non-infected vaccinated individuals.

Covaxin, developed jointly by Bharat Biotech and the Indian Council of Medical Research, had earlier demonstrated a 77.8% efficacy against symptomatic Covid-19 cases and provided 65.2 per cent protection against the Delta variant.

Dr. Panda said Covaxin remained effective despite a slightly reduced neutralisation antibody titre and it would not be detrimental to the vaccination drive.

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