“These results demonstrate the protective efficacy in a live viral challenge model,” said Bharat Biotech.

Covaxin, being developed by the Indian Council of Medical Research and Bharat Biotech, is being tested at 12 institutes across India.

A tw-dose vaccination regimen of inactivated SARS-CoV-2 vaccine candidates was administered in 20 rhesus macaques (divided into four groups equally).

One group was administered with placebo, while three groups were immunized with 3 different vaccine candidates at 0 and 14 days. All the macaques were exposed to viral challenge 14 days after the 2nd dose.

The results showed protective efficacy, increasing SARS-CoV-2 specific IgG and neutralizing antibodies, reducing replication of the virus in the nasal cavity, throat, and lung tissues of monkey.

No evidence of pneumonia was observed by histopathological examination in vaccinated groups, unlike the placebo group, the company said.

Adverse events were not seen in animals immunized with a two-dose vaccination regimen.

“The vaccine candidate was found to generate robust immune responses. Thus, preventing infection and disease in the primates upon high amounts of exposure to live SARS-CoV-2 virus,” Bharat Biotech summarised in its report.

Earlier this week, Post Graduate Institute (PGI) Rohtak said it will start the phase-2 human clinical trial of Bharat Biotech’s Covid-19 vaccine.

Speaking to ANI, Dr OP Kalra, vice-chancellor, PGI Rohtak said, “We got permission from Bharat Biotech to start a phase-2 human clinical trial of their vaccine. We’ve 300 volunteers, aged between 12 years and 65 years, out of which screening of 15 has been completed.”