Covaxin booster effective against emerging Covid-19 variants: Study

Vaccine maker Bharat Biotech said that Covaxin shows immunity persistence and impact of third dose against the emerging variants of Covid-19.

Citing a peer reviewed study published in Nature Scientific Reports, the Hyderabad based firm said that its inactivated Covid‐19 vaccine has shown multiple benefits like long term immune response, cell mediated immunity, safety of booster dose, immunogenicity against spike protein, N protein and neutralizing antibody responses against alpha, beta, delta, delta plus and omicron variants of Covid-19.

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The study comes at a time when the demand for Covid-19 vaccines has gone down, following the optimal coverage of the eligible population with the first and second doses. The Narendra Modi government had initiated the supply of free booster doses for the 18-60 years age group too, as part of Azadi ka amrit mahotsav, from 15 July.

“Administration of a third dose of Covaxin, after six months of two dose vaccination, dramatically increased neutralizing antibody responses against both homologous and heterologous strains (Alpha, Beta, Delta, Delta Plus and Omicron) and showed increased memory B cell response,” Bharat Biotech said, referring to the “comprehensive study.”

The study was conducted in 184 subjects, who received either a Covaxin booster dose or a placebo, six months after the primary series of two doses.

Immune responses declined at six months and increased by 40 fold in subjects who received a booster dose. Immune responses when assessed against variants of concern persisted up to 12 months.

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“Covaxin induced robust T cell responses and persisted till six months, even after antibody decline. These T cell responses have been followed up to 12 months in vaccinated individuals, irrespective of receipt of third dose. T cell responses in turn help to produce B cell memory response, upon antigen re-exposure. Thus, Covaxin provides long term immunity.”

Dr Krishna Ella, Chairman and Managing Director, Bharat Biotech, said, “Covaxin is a multi epitope vaccine with antibodies against spike, RBD and N proteins. Post booster dose, it has proven neutralizing antibody responses against variants of concern and long term protection through memory T and B cell responses. We have thus developed a safe and efficacious vaccine with long term protection against a spectrum of variants.”

Covaxin or BBV152, indigenously developed by the Indian Council of Medical Research and Bharat Biotech, is an inactivated whole virion SARS-CoV-2 vaccine. Same dosage can be administered to adults and children, in primary and booster doses. Covaxin is a ready to use liquid vaccine, stored at 2-8°C, with 12 months shelf life and multi-dose vial policy.