Covaxin booster dose effective against emerging variants

IndiGlobal Bureau

Bharat Biotech today announced that BBV152 (COVAXIN), its whole- virion inactivated Covid-19 vaccine, has proven to be safe, well- tolerated, and immunogenic in subjects in controlled clinical trials. The study has been accepted and published in Nature Scientific Reports, a high impact factor journal.

The study was conducted in 184 subjects, who were randomized 1:1 and received either a booster dose of BBV152 or a placebo, 6 months after the primary series of 2 doses. Subjects were evaluated for safety, neutralizing antibody responses against variants of concern, binding antibodies against spike protein, RBD, N proteins, and for memory T and B cell responses to demonstrate cell mediated immunity.

Covaxin demonstrated persistence of immunity and impact of third dose of inactivated Covid‐19 vaccine against emerging variants. The study demonstrated multiple benefits of Covaxin, such as 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.

Administration of a third dose, after 6 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.

Covaxin induced robust T cell responses and persisted till 6 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.

Immune responses declined at 6 months, but increased by 40 fold in subjects who received a booster dose.

No serious adverse events observed, except pain at the injection site, itching and redness, no cases of myocarditis, pericarditis, blood clots, or thrombocytopenia were detected.

Dr. Krishna Ella, Chairman and Managing Director, Bharat Biotech, said, “Our team has now demonstrated that 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 now achieved our goal of developing a safe and efficacious vaccine with long term protection against a spectrum of variants.”