The phase-three human clinical trial of indigenously developed anti-coronavirus vaccine candidate Covaxin began at the AIIMS here on Thursday with Dr M V Padma Srivastava, the chief of Neurosciences Centre at the premier institute, and three other volunteers receiving the first dose.

'Covaxin' is being developed by Bharat Biotech in collaboration with the Indian Council of Medical Research (ICMR).

Dr Srivastava was the first one to receive the shot, which would be given to around 15,000 volunteers at the AIIMS over the next few days, sources said.

The first dose of 0.5 ml intramuscular injection was given to four volunteers. They were under observation for two hours and will be monitored for the next few days, a source said.

When contacted, Dr Srivastava said, "Covaxin is the first indigenously-developed anti-coronavirus vaccine and on top of that, my institute is participating in the trial. I am honoured to be the first volunteer to receive the shot. I am happy to be a part of such a great cause. I am perfectly fine and I'm working."

As part of the trial application, a dose of 0.5 ml would be given on day 0 and on day 28, sources said.

The phase-three randomised double-blind placebo-controlled multi-centre trial would cover around 28,500 subjects aged 18 years and above. It would be conducted in around 25 sites across 10 states. The trial has already started at a few sites.

The Bharat Biotech has been given permission for conducting phase-3 human clinical trials of the Covaxin from the Drugs Controller General of India (DCGI).

The safety and immunogenicity data of phase one and two trials were submitted to the central drug regulator. The Hyderabad-based firm, while applying for a phase-three trial, stated that the vaccine was well-tolerated in all dose groups and no serious adverse events have been reported.

The most common adverse event was pain at the injection site, which resolved transiently, the source said.

Besides, Covaxin, four other vaccines are under different phases of a clinical trial in India with the Serum Institute of India conducting a phase-three trial of the Oxford-Astrazeneca COVID-19 vaccine while the indigenously developed vaccine by Zydus Cadila has completed a phase-two clinical trial in the country.

Dr Reddy's Laboratories will soon start combined phase two and three clinical trials of the Russian COVID-19 vaccine Sputnik V in India. Also, Biological E. Ltd has started early phase 1 and 2 human trials of its COVID-19 vaccine candidate, officials had said last week.