Though the first interim analysis is based on only 43 cases, which is smaller compared with other vaccines that have been approved by other regulators, the vaccine appears safe and efficacious in phase-3 and early stages of human clinical trials and animal studies. The Indian regulator should therefore revise the restricted emergency use approval such that Covaxin is treated on a par with Covishield.
Vaccine efficacy of 80.6% for Bharat Biotech’s Covaxin at the first interim analysis of phase-3 trials in India is indeed promising, though it took two months for the data to become available after the vaccine was approved for ‘restricted emergency use’ by the Indian drug regulator.
The vaccine efficacy was measured based on symptomatic COVID-19 disease — mild, moderate or severe — two weeks after the second dose. The interim analysis undertaken at the first endpoint of 43 COVID-19 cases in the phase-3 trial carried out across 26 sites in India found 36 cases in the placebo group while only seven COVID-19 cases in the arm that received two doses of the vaccine given 28 days apart.
The phase-3 trial that began in mid-November last year recruited 25,800 participants in all, with one half receiving the vaccine and the other half receiving a placebo. While the phase-3 trial will continue till 130 participants in both groups put together develop COVID-19 disease, another interim analysis will be carried out when there are 87 cases.
Covaxin efficacy better than Covishield’s
Covaxin’s efficacy of 80.6% at first interim analysis is higher than AstraZeneca/Covishield vaccine efficacy of 55·1% when the second dose is administered less than six weeks after the first; in India, the second dose of Covishield is approved for four-six weeks after the first.
Also, the phase-3 trial recruited 2,433 participants over the age of 60 years and included 4,500 people with comorbidities. However, those with severe and/or uncontrolled comorbidities including cardiovascular disease, respiratory disease, liver disease and renal disease were not recruited.
Safety and efficacy
As per the phase-1 data published in The Lancet Infectious Diseases journal and a preprint of the phase-2 trial, Covaxin appears to be safe and highly immunogenic; the vaccine was found to be safe and efficacious in hamsters and rhesus monkeys too. The vaccine has also been found to be effective against the B.1.1.7 variant first found in Britain.
While Covaxin accounts for only less than 10% of all COVID-19 vaccinations in India, the absolute number of people vaccinated with Covaxin as on March 3 stands at over 1.3 million. No deaths, whether connected or unconnected with Covaxin, have been reported so far.
Treat Covaxin on a par with Covishield
Though the first interim analysis is based on only 43 cases, which is smaller compared with other vaccines that have been approved by other regulators, the vaccine appears safe and efficacious in phase-3 and early stages of human clinical trials and animal studies. The Indian regulator should therefore revise the restricted emergency use approval such that Covaxin is treated on a par with Covishield and should no longer seek additional precautions in the form of a signed consent from people prior to getting vaccinated and also remove the label “clinical trial mode” from the approval.
Any continuation of these additional precautions would send a wrong signal about its safety and efficacy resulting in less uptake of the vaccine. With a narrow window of opportunity available to vaccinate people before a second wave probably sets in or dangerous variants get established, India can ill afford any roadblocks in the uptake of either vaccine.
Science Chronicle 