Final phase 3 trials data on Covaxin in July, says Bharat Biotech; experts question delay

Express News Service
NEW DELHI: The wait for the published data related to phase 3 clinical trials of Covaxin is only getting longer despite a growing clamour to release the findings urgently amid new information that compared to Covishield this Covid-19 vaccine may be triggering lower antibody response.

On Wednesday, Bharat Biotech, which has developed Covaxin with support from ICMR, said that the final analysis of its efficacy trials that were carried out between November-January will be made public only in July, after it is submitted to the drug regulator and peer-reviewed journals with a timeline of about three months for publication.

While announcing the second interim analysis of its phase 3 trials on April 20, the company had said that “safety and efficacy results from the final analysis will be available in June, and the final report will be submitted to a peer-reviewed publication”.

In this statement, the company had claimed that the vaccine has shown a 78% efficacy against preventing infection while efficacy against severe Covid-19 disease was 100%, with an impact on reduction in hospitalizations after studying 127 symptomatic cases.

This efficacy was lower by 3% from the one claimed in another statement to the press, issued in early March, based on 87 symptomatic cases.

But a delay on the part of the company in coming up with the final data is bothering many — since phase 3 trials data of all other approved Covid-19 vaccines, including the Russian Covid-19 vaccine Sputnik V, were published within 4-6 weeks of interim analysis.

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Also, Covaxin had been approved by the Central Drugs Standard Control Organisation for public use in “clinical trial mode” while still under efficacy trials on 25,800 people.

“It is unusual to have such a delay, particularly when the second analysis was so close to the sample size of 130 symptomatic cases,” said a top virologist who did not wish to be named.

Health systems and vaccine policy expert Chandrakant Lahariya said that while publication in a journal may take time, the company should at least release the findings on a pre-print server in the interim.

The voices demanding proof that Covaxin actually protects against Covid-19 are also growing because a recent comparative report on evaluation of immunogenicity responses to spike protein after the first and second doses of Covaxin and Covishield showed that the former may have lower immunogenicity.

Though some experts say that the low antibodies after Covaxin is expected given that it is an inactivated virus based vaccine known for triggering cellular rather than just antibody response, these doubts can be put to rest only when data is out for independent researchers to see and analyse.

“It would be really useful to see published phase 3 results of Covaxin,” said vaccinologist Shahid Jameel. “Peer-reviewed publications are globally considered to be the best way of judging science, and it would be a tribute to India’s vaccine effort. It will also help Covaxin to quickly get WHO qualification.”

Amar Jesani, a bio-ethics researcher and editor of the Indian Journal of Medical Ethics, said he was surprised that the final data has not been submitted even to the regulator yet.

“This is particularly surprising because the regulator recently approved Covaxin trials for kids and adolescents aged 2-17 years who should not be subjected to any experiment until the vaccine’s protection in adults is fully understood and analysed,” he said.

Jesani minced no words in saying that Indian drug regulator has been lax in the case of Covaxin.

“I think Bharat Biotech and ICMR are getting extraordinary privileges while science is taking a backseat. Such leniency would not have happened if this vaccine would have aimed to be marketed in developed countries,” he said.