The government on Tuesday cleared the air on the restricted emergency use approval granted to two Covid-19 vaccines — Serum Institute of India’s Covishield and Bharat Biotech’s Covaxin — as the debate heats up over the move.
While Balram Bhargava, director general of the Indian Council of Medical Research (ICMR), defended the approval by the Indian regulator based on safety and immunogenicity data, the minutes of the meeting of the Subject Expert Committee (SEC) that recommended the approval were also made public.
This comes after experts raised questions over the approvals, especially for Covaxin, which is yet to generate and submit efficacy data from phase-III trials.
Bhargava said the SEC considered the pandemic situation with high mortality and lack of definitive treatment while recommending restricted use approval. He said immunogenicity and efficacy data is required for approval in non-emergency situations. “While phase-III is still ongoing, immunogenicity data generated through phase-II clinical trial serves as a surrogate for efficacy,” Bhargava said.
Meanwhile, minutes of the SEC meeting held on January 1 (the day Covishield got approval) shows that the committee noted that the data generated so far demonstrates a strong immune response (both antibody as well as T cell) and in-vitro viral neutralisation.
“The ongoing clinical trial is a large trial on 25,800 Indian subjects in which already 22,000 subjects have been enrolled, including subjects with comorbid conditions as well, which has demonstrated safety till date. However, efficacy is yet to be demonstrated,” it said. Therefore, after “detailed deliberation” the SEC recommended that the firm “should try to expedite the recruitment and may perform interim efficacy analysis for further consideration of restricted emergency use approval”.
Covaxin received approval on January 2, and the SEC noted on that day that since Bharat Biotech has presented safety and efficacy data from non-human primate challenge study, where it was found to be safe and effective, the SEC recommended grant of permission for restricted use in emergency situation in “public interest and as an abundant precaution in clinical trial mode”. This, the committee felt, would provide more options for vaccinations, especially in case of infection by mutant strains.
Krishna Ella, CMD of Bharat Biotech, had said on Monday that Covaxin had demonstrated 100 per cent results in animal challenge studies (non-human primates), which means when exposed deliberately to the pathogen after vaccination, the animals did not get the disease. This along with the safety and immunogenicity data (whether the vaccine induces desired immune response), led to the quick approval.
Speaking to reporters, Bhargava said approval for restricted use of Covaxin in clinical trial mode meant that beneficiaries will have to give consent and there will be regular follow up. Such persons will not receive the placebo.
He added that the first two phases of trials of Covaxin on 375 and 380 participants, respectively, showed very less adverse events and strong antibody responses to all structural proteins. For Covaxin, the Indian studies on animals including young rats, mice, rabbits, hamsters, and monkeys showed excellent safety immunogenicity and robust viral clearance in both in the upper and lower respiratory tracts, Bhargava said. As part of Covaxin’s phase-III trial, 24,000 volunteers have been enrolled and 5,000 of them have received the second dose.
As for Serum Institute's Covishield, the SEC has recommended restricted emergency use subject to various regulatory provisions.