By Devjyot Ghoshal and Sachin Ravikumar
NEW DELHI/BENGALURU (Reuters) - The chief of India's top clinical research agency said in a leaked letter circulated on Friday it envisaged launching a novel coronavirus vaccine by Aug. 15, prompting scepticism from some health experts who questioned the short timeline.
Dozens of vaccine candidates are at various stages of development around the world to tackle the coronavirus pandemic.
One, from India's Bharat Biotech and being developed with the Indian Council of Medical Research (ICMR), was this week approved for Phase I and Phase II clinical trials.
"It is envisaged to launch the vaccine for public health use latest by August 15, 2020, after completion of all clinical trials," ICMR Director General Balram Bhargava said in the letter, dated July 2 and addressed to institutions involved in the trials.
Phase I and Phase II trials typically test the safety of a drug before it enters Phase III trials that test its efficacy.
Each phase can last months, if not years, and although regulators globally have been fast-tracking trials on medicines and vaccines to treat the novel coronavirus, the timeline envisaged in the letter would be unprecedented.
"To my knowledge, such an accelerated development pathway has not been done EVER for any kind of vaccine, even for the ones being tried out in other countries," Anant Bhan, a doctor and public health researcher, said on Twitter.
"Even with accelerated timelines, this seems really rushed, and hence with potential risks, inadequate attention to process."
Several other health experts also questioned the launch date proposed in the letter, which was widely shared on social media.
A spokesman for ICMR did not respond to phone calls and text messages seeking comment on Friday. However, an ICMR official, who asked not to be identified, said the letter was a private communication and was being misinterpreted.
The official said the aim was to complete all trials on the vaccine candidate by Aug. 15, and did not say when he thought it might be launched for public use.
A Bharat Biotech spokesman declined to comment on the letter. But in an emailed statement to Reuters, Bharat Biotech's Managing Director Krishna Ella said the company had a target to produce up to 300 million doses of the vaccine per year if it succeeds in clinical trials.
"Enrolment of the cohort for the phase I is underway," Ella said, adding the company was awaiting approvals for human clinical trial vaccine batches from the Indian regulator.
Separately on Friday, Indian drugmaker Zydus Cadila said it had secured regulatory approval to start human trials on its own COVID-19 vaccine contender. It plans to start trials this month in over 1,000 subjects in India.
(Reporting by Sachin Ravikumar, Anuron Kumar Mitra and Devjyot Ghoshal; Writing by Zeba Siddiqui; Editing by Euan Rocha, Robert Birsel and Mark Potter)