The Phase-III human trials of indigenous Covid-19 vaccine Covaxin began at All India Institute of Medical Science (AIIMS) in New Delhi on Thursday.M V Padma Srivastava, the chief of Neurosciences Centre and three other volunteers received the first dose of Covaxin.Around 15,000 volunteers at AIIMS will be given the shot as part of the clinical trials.Bharat Biotech announced the commencement of Phase-III trials of Covaxin on November 16. The Phase-III trials will involve 26,000 volunteers across India, conducted in partnership with ICMR.It is the largest clinical trial conducted for a COVID-19 vaccine in India. This is India's first Phase-III efficacy study for a COVID-19 vaccine, and the largest phase III efficacy trial ever conducted in India.Trial volunteers will receive two intramuscular injections approximately 28 days apart. Participants will be randomly assigned to receive Covaxin or placebo. The trial is double blinded, such that the investigators, the participants and the company will not be aware of who is assigned to which group.Covaxin has been evaluated in 1,000 subjects in Phase-I and Phase-II clinical trials, with promising safety and immunogencity data. Volunteers who wish to participate in this trial should be adults over 18 years of age.Covaxin, India's indigenous COVID-19 vaccine by Bharat Biotech is developed in collaboration with the Indian Council of Medical Research (ICMR) - National Institute of Virology (NIV).This indigenous, inactivated vaccine is developed and manufactured in Bharat Biotech's BSL-3 (Bio-Safety Level 3) bio containment facility. Covaxin is a highly purified and inactivated vaccine, manufactured in a vero cell manufacturing platform with an excellent safety track record of more than 300 million doses supplied.This multicenter phase-III study is conducted at the following sites across India. Participating Volunteers who undergo vaccination in the Phase-III trials, will be monitored to detect occurrence of COVID-19 disease.