Hyderabad-based Bharat Biotech on Friday announced that the Phase-I clinical trials of India's first indigenous COVID-19 vaccine Covaxin began across the country on July 15. "This is a randomised, double-blind, placebo-controlled clinical trial on 375 volunteers in India," the company said in a brief statement.

The leading vaccine maker had announced on June 29 that it successfully developed Covaxin in collaboration with the Indian Council of Medical Research (ICMR) and National Institute of Virology (NIV).

The SARS-CoV-2 strain was isolated in NIV, Pune and transferred to Bharat Biotech. The indigenous, inactivated vaccine was developed and manufactured in Bharat Biotech's BSL-3A (Bio-Safety Level 3) High Containment facility located in Genome Valley, Hyderabad.

The Drug Controller General of India - Central Drugs Standard Control Organisation (CDSCO), Ministry of Health & Family Welfare granted permission to initiate Phase-I and II human clinical trials after the company submitted results generated from pre-clinical studies, demonstrating safety and immune response. The Nizam's Institute of Medical Science (NIMS), Hyderabad is one of the 12 centres selected by the ICMR for the clinical trials.

The subject enrolment for Phase-I clinical trials at the NIMS began on July 7. There was no clarity on the number of subjects selected at this centre.

The officials had earlier said that for two days after administering the vaccine, the subjects would be monitored in the ICCU at the NIMS by a team of doctors, after which they would be sent home and monitored through video conference or phone.

The Phase-I clinical trial would go on for 28 days, after which the ICMR and Drug Controller General of India would accord permission for Phase-II, which will include more subjects.

Phase-1 would have around 375 subjects across the country and Phase-II, 875.

In a letter to the selected centres early this month, ICMR Director General Balram Bhargava asked them to fast-track all approvals related to initiation of the clinical trial.

"It is envisaged to launch the vaccine for public health use latest by 15th August 2020 after completion of all clinical trials. BBIL is working expeditiously to meet the target, however the final outcome will depend on the cooperation of all clinical trial sites involved in this project," reads the letter dated July 2.

While experts raised doubts on the August 15 target, the ICMR defended it, saying its process is in accordance with the globally accepted norms to fast-track vaccine development for diseases of pandemic potential.

The research body said Bhargava's letter was intended to cut red-tape, without bypassing any necessary process, and speed up recruitment of participants for human trials so that these phases can be completed at the earliest.

Bharat Biotech had refused to comment on the ICMR's August 15 deadline.