Full-fledged authorisation for coronavirus vaccines can be granted only after 12 months of follow-up on 'efficacy' and 'safety' from the date of presentation of the Phase III clinical trials data, says World Health Organization's Chief Scientist Dr Soumya Swaminathan.
At least 13 vaccines are in various states of trials across the world while 6 of them are vying to be the first to get Full authorisation, including Pfizer, Moderna, AstraZeneca-Serum-Oxford, Bharat Biotech, Gamaleya and Sinopharm.
Full authorisation-better known as "full pre-qualification"-is a pre-requisite to sell the vaccines in the open market or for mass immunisation programme of healthy individuals who are neither frontline workers, nor directly at risk. WHO also examines manufacturing standards before qualifying a vaccine for rollout.
"For full pre-qualification, we would need to see the final data from these [Phase III] clinical trials, both on efficacy and safety, with at least 12 months of follow-up. For pre-qualification, we also look at a lot of the manufacturing standards. There's a whole check list to do that," the veteran medical researcher added.
At least 13 vaccine manufacturers have approached WHO for approval.
"A vaccine should prove to be at least 50 per cent efficacious with a lower border of confidence of not less than 30 per cent. Now this was set a time when we did not know what the efficacy of vaccines against this virus is going to be. It's very encouraging to see so many vaccine candidates that seem to have efficacies of over 80 per cent, or even over 90 per cent. Similarly, for safety, the developer needs to provide at least two months of follow-up data from Phase III clinical trials," she says.
"We have currently issued emergency use listing for the Pfizer-BioNTech vaccine. We are currently looking at the dossiers for Moderna, for AstraZeneca. We are awaiting the dossier from the Serum Institute of India. We are also looking at Sinopharm and Sinovac from China and the Gamaleya product from Russia. We have at least 13 manufacturers who have submitted initial interest and dossiers but they will keep on adding the data as they collect from their studies," she informed.
Responding to a question on guidelines prescribed by the WHO for clinical trials, Dr Swaminathan says: "We have provided guidance on what the clinical trial should look like. It should be about 20,000 patients per arm. But this can change a little bit based on the incidence of disease and so on. In countries which have very high incidence of disease you can get the end points much earlier, you could stop earlier. As a disease dies out in some countries, or the infection rates fall, it becomes that much more difficult. So it takes longer to accumulate the end points."
Dr Swaminathan believes the expeditious development of coronavirus vaccines can be emulated in preparing inoculations and remedies for other diseases as well. Citing the example of tuberculosis, she expects shorter treatment regimens of one to two months, instead of current regimens which extended from six months to two years.
"... It takes so long to go from Phase I to Phase II to Phase III. There's a lack of interest, there's a lack of funding... For drugs for TB, it will be wonderful to have a short course regimen of one month or two months to be able to cure TB of all types completely, instead of these long courses of six months for drug-sensitive and up to two years for drug-resistant TB with a lot of toxic drugs that the patients have to take. There's a lot of scope now that we have a proof of principle that it can be done for one infection, it should be possible for others," Dr Swaminathan says.
The WHO Chief Scientist also expressed concerns over difficulties in conducting placebo-controlled trials for testing efficacy and safety of vaccines as several countries roll out vaccination programmes for their citizens. She emphasised on the need for protocols to study people who have been vaccinated for safety and efficacy of the administered vaccines.
"Next week we have a big global meeting on the vaccine priorities for 2021, which are clearly different from what it was in 2020. We're also having a big meeting to look at this new variant and what global research needs to focus on," she says.