Pharmaceutical major Bharat Biotech on July 20 said its COVID-19 vaccine Covaxin 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. A press release from the vaccine maker said the study was conducted on 184 subjects, who were randomised 1:1 and received either a booster dose of Covaxin or a placebo, six months after the primary series of two doses.

Subjects were evaluated for safety, neutralising antibody responses against variants of concern, binding antibodies against spike protein, RBD, and N proteins, and for memory T and B cell responses to demonstrate cell-mediated immunity, it said.

Krishna Ella, chairman and managing director, of Bharat Biotech, said the 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 neutralising 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," Ella said.

Covaxin is formulated uniquely such that the same dosage can be administered to adults and children alike, for primary and booster doses, making it truly a universal vaccine, the company release said. The jab is a ready-to-use liquid vaccine, stored at 2-8 degrees Celsius, with 12-month shelf life and a multi-dose vial policy.

Bharat Biotech has a stockpile of more than 50 million doses of Covaxin ready to be distributed as and when required.