New Delhi, October 10: Bharat Biotech, which had sought DCGI's nod for conducting phase-3 clinical trials of its COVID-19 vaccine candidate, has been asked to submit complete safety and immunogenicity data of the ongoing phase-2 trial, besides providing some clarifications, before proceeding for the next stage.

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

According to officials, the Hyderabad-based vaccine maker applied to the Drugs Controller General of India (DCGI) on October 2, seeking its permission to conduct phase-3 randomised double-blind placebo-controlled multicentre trial of its COVID-19 vaccine candidate. COVID-19 Vaccine Update: UK May Inject Volunteers with Coronavirus for Vaccine Trials, Says Report.

The firm in its application said that the study would cover 28,500 subjects aged 18 years and above and would be conducted in 19 sites -- including Delhi, Mumbai, Patna and Lucknow -- across 10 states.

According to sources, the phase-2 trial of the Covaxin is going on and the second dose is yet to be given to volunteers at some sites. "The company presented phase-3 clinical trial protocol along with interim data of phase 1 and 2 clinical trials," an official said. The subject expert committee (SEC) at the Central Drugs Standard Control Organisation(CDSCO) deliberated on the application on October 5.

"After a detailed deliberation, the committee opined that the design of the phase-3 study is in principle satisfactory except for clarification on definition of asymptomatic, etc.

"However, the study should be initiated with appropriate dose identified from the phase-2 safety and immunogenicity data. Accordingly, the firm should submit safety and immunogenicity data from phase-2 trial for consideration," the panel said in its recommendations.

The SEC during its discussion also observed that the vaccine was well-tolerated in all dose groups and no serious adverse events have been reported so far, a source said. The most common adverse event was pain at the injection site, which resolved transiently, the source said. The phase-3 clinical trial application proposed a dose of 0.5 ml on day 0 and 28, sources said. US President Donald Trump Urges Citizens to Enroll in COVID-19 Vaccine Trials.

Besides, Bharat Biotech, indigenously developed vaccine candidate by Zydus Cadila Ltd is in the phase 2 of the human clinical trials. The Pune-based Serum Institute of India, which has partnered with AstraZeneca for manufacturing the Oxford COVID-19 vaccine candidate, is also conducting Phase 2 and 3 human clinical trials of the candidate in India.