COVID-19 vaccine: Unlike the Serum Institute of India's (SII) vaccine Covishield, Covaxin will be used only in 'clinical trial mode', where consent will be taken and side-effects monitored, the heads of AIIMS and ICMR, part of the National Covid-19 task force, told The Indian Express.
The indigenous vaccine developed by Bharat Biotech with the Indian Council of Medical Research (ICMR) will be used as a “back-up”, only if the country needs extra doses to vaccinate a large number of people, particularly given the possibility of a surge triggered by the UK variant. And, unlike the Serum Institute of India’s (SII) vaccine Covishield, Covaxin will be used only in ‘clinical trial mode’, where consent will be taken and side-effects monitored, the heads of AIIMS and ICMR, part of the National Covid-19 task force, told The Indian Express.
On Sunday, Indian regulator Drug Controller General of India (DCGI) approved the Subject Expert Committee’s recommendation for emergency use of Covishield and Covaxin. While Covishield is the same vaccine as developed by Oxford-AstraZeneca, that has got emergency use approval in the UK, in case of Covaxin, concerns have been raised about the absence of efficacy data, which is generated during Phase 3 of human clinical trials. The decision to grant emergency approval to Bharat Biotech is based on only immunogenicity, the ability to trigger an immune response, and safety data generated in Phase 1 and 2 clinical trials.
However, the members of the national task force, including AIIMS Director Dr Randeep Guleria and ICMR Director General Dr Balram Bhargava, emphasised that the approval granted to Bharat Biotech is distinctly different from the one to the SII.
Said Dr Guleria: “This is like a back-up. If we find that cases don’t rise, then we stick to the SII, till the Bharat Biotech data comes early next month. And if that data is found to be good enough, then they will get the same approval as the SII. Indirectly, looking at the safety profile, that (Covaxin) is a safe vaccine, although we don’t know how efficacious it is. They (the regulators) have given, I would say, a green signal to start stockpiling in case we need it.”
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As a vaccine that uses a platform used for traditional vaccines in India, which targets the whole virus for antigen response, Covaxin is also considered by some to be more effective against any mutations.
“It (the approval to Covaxin) says it may be used in an emergency situation, which means that because of what is happening in the UK, Europe, and the US, in case there is a sudden surge in number of cases in the country, and considering that we have no anti-viral drug still available against Covid-19, if vaccination may prevent spread of an infection, only in such circumstances — when there is a need to vaccinate a large number of people, that cannot be done using only the SII’s vaccine — Bharat Biotech would be allowed to give the vaccine,” Dr Guleria said.
In the absence of efficacy data, he emphasised the “abundant precaution” to be observed in Covaxin’s use. “… This will be in clinical trial mode, so that there is very close monitoring from the point of view of safety and side-effects. It will not be like the usual marketing of a vaccine (for commercial use). It will be like a trial, where they will be called up frequently about the side-effects, and a database will be maintained.”
The AIIMS Director compared the scientific rationale behind clearing Covaxin to the grant of approval to repurposed drugs like hydroxychloroquine and remdesvir for treating symptoms arising from Covid-19. “We are looking at two things: safety and efficacy. If you have data that the vaccine is safe, or any drug is safe, then you would say that in case there is a need, we may consider using it without knowing that it would work 20 per cent or 80 per cent. This is what was done even when approving hydroxychloroquine or remdesivir or even convalescent plasma,” Dr Guleria said. “Regarding this vaccine, there is data which shows good immunogenicity and safety.”
Dr Bhargava, the head of the ICMR that co-developed Covaxin with Bharat Biotech, said, “In terms of the efficacy data, we have done extensive work at the NIV, Pune. There have been small animals’ study, large animals’ study and monkey challenge study. And a huge study with bronchoscopy done at the ICMR for 14 days (in monkeys), where samples were taken every day and looked at for efficacy,” he said.
“In the Phase 1 human trials data, that included 375 patients, and the 380 participants in Phase 2, we did not find any case of anyone getting Covid-19,” Dr Bhargava said, adding that even in Phase 3, no safety concerns had been reported from the 22,500 participants.
Bharat Biotech had announced the commencement of Phase 3 trials on November 16. On Sunday, the government’s press statement said the Phase 3 trials had been initiated in 25,800 volunteers, of whom 22,500 had received the first dose. Covaxin is injected intramuscularly twice, with a gap of 27 days. The interim safety data is expected next month.
Dr Bhargava said that Covaxin’s potential in mounting a resistance against the new mutant strain was a key factor in granting the emergency approval. “It is now present in 34 countries. Some of the vaccines just target the spike protein of the virus, and these may not be effective. From that perspective, we are looking at a whole virus vaccine (Covaxin), which potentially may have benefits,” he said.
However, Dr Guleria admitted that, at this point, more lab data is required on Covaxin providing any protection against the new UK variant. “Bharat Biotech uses an inactivated virus, using the platform deployed in other vaccines in our country. The evidence that is being put forward is that because the whole virus is being used as the antigen, the antibody response may be more robust to take care of any mutation… However, we will need more lab data to be able to confirm this,” he said.
“The bottom line is that, if we don’t have any surge in cases, then we would use the SII vaccine. That is what my understanding is after reading the recommendation. And, if there is an emergency need, in clinical trial mode and taking abundant precautions, we may use the Bharat Biotech vaccine. Otherwise, we wait for four-six weeks till the final data is out,” Dr Guleria said.
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