The refusal rate of phase-3 trial is much higher than for phase 1 and phase 2 trials, Dr Sanjay Rai said.
Despite phase-1 trial of its Covaxin vaccine seeing "encouraging" results, Hyderabad-based Bharat Biotech is facing challenges in phase 3 trials of its vaccine in India, a top official associated with the project told NDTV.
The drugmaker has witnessed 70%-80% reduction in participation for Covaxin trial, according to Dr Sanjay Rai who is Principal Investigator of Phase 3 Covaxin trial at AIIMS.
"People are unwilling to participate in the trial because they think that a vaccine is coming for everyone soon. AIIMS Delhi needs 1,500- 2,000 participants for phase-3 trial of Covaxin, but only 200 have enrolled so far," Dr Rai told NDTV.
The refusal rate of phase-3 trial is much higher than for phase 1 and phase 2 trials, which was less than 10 per cent, he said.
"For phase 1 we were flooded with applications, 100 participants were needed and 4,500 had applied. Volunteers who are coming for phase-3 have to be told clearly by authorities as part of protocol that it is a trial only and they refuse. Many are under the assumption that a vaccine is anyway coming to India for everyone within a week or 15 days and so they don't want to become part of a trial," he said.
Bharat Biotech's Covaxin is among the three companies that have applied for emergency use authorisation to the Indian drug regulator. ICMR (Indian Council of Medical Research) which is a partner in the clinical trials of Covaxin, today announced that results of phase-1 trial are "encouraging".
The Phase-1 results, Dr Rai said, reflect that vaccine is "safe and has negligible side-effects". "Covaxin also induced immune response. The immediate safety concerns have been addressed by phase-1 results," he added.
Though there was one serious adverse event with 1 trial participant but it was later found that it was not associated with the vaccine, he said.
Though the Indian drug regulator has sought data of phase 3 trial, the approval, according to Dr Rai, may come through only if the drug regulator is satisfied with data of phase 1 and phase 2 trial and how similar vaccines are being used in China.
On being asked whether the challenges with phase-3 will affect the emergency use authorisation for Covaxin, Dr Rai said, "There are similar vaccines that are based on 'whole-virion' concept and they have been approved in China. If the drug regulators are satisfied based on phase-1 and phase-2 results of Covaxin as well as what is happening in China, they may give a go-ahead. If they think its sufficiently safe and generates immune response. But it is entirely the prerogative of the subject expert committee of the Indian drug regulator."
Posters are also being circulated to the people to create awareness and for seeking volunteers for the trial. Posters are being put up by AIIMS and Sir Gangaram Hospital in Delhi, which are among the sites for the phase-3 trials.
Phase 3 trials of Covaxin are meant to be conducted upon a total of 25,800 participants across 25 different sites in India.