Covaxin’s Phase 3 full trial data to be released in July, but what led to delay?

The vaccine’s manufacturer, Bharat Biotech said the phase 3 data will first be submitted to CDSCO, followed by peer-reviewed journals.

Covaxin’s Phase 3 full trial data to be released in July, but what led to delay?
Bharat Biotech's Covaxin being sent to foreign nations. (Photo credit: @DrSJaishankar)

New Delhi: Indian vaccine manufacturer Bharat Biotech, the makers of Covaxin, will be releasing the Phase 3 results full trial data in July, and not June as announced by it earlier.

“It is critical to understand, and further emphasise the phase 3 data will first be submitted to Central Drugs Standard Control Organisation (CDSCO), followed by peer-reviewed journals, with a timeline of three months for publication, and as communicated earlier, Covaxin phase 3 results full trial data will be made public during July,” the company said on June 9.

The Hyderabad-based company said it would seek full licence for Covaxin, which has been granted emergency use authorisation by the country’s drug regulator that waived its ‘clinical trial mode’ approval in March without complete data.

“Ph 3 Timelines and reasons to trust the process: Largest efficacy trial conducted in the developing world (sample size=25,800). The last volunteer was vaccinated in Mid March. Mandatory CDSCO/FDA requirement of a 2-month safety follow-up for all volunteers landed us in Mid May,” Dr Raches Ella, Project Lead COVID-19 Vaccines at Bharat Biotech said in a tweet.

The first interim results of Phase 3 trials of the indigenous vaccine were released on March 3 and the second on April 21 and the third and final interim results are awaited.

While other vaccine makers like Pfizer released the entire set of data within a period of nine days. Russian Covid-19 vaccine Sputnik V’s Phase 3 trial data was published within 4-6 weeks of interim analysis.

While announcing the second interim results of Phase 3 trials, the company said “safety and efficacy results from the final analysis will be available in June”.

Reason behind delay

Dr E Venkata Rao, Principal Investigator of the trial at the Institute of Medical Sciences and SUM Hospital, Bhubaneswar, Odisha, told TV9 News that final interim results can be known in a day, but since the profile of all the positive subjects has to be studied and can be withheld due to lack of any single data.

“Each and every query has to be resolved otherwise that subject will be a dropout. Once there is a case of drop out the power of the study diminishes. We don’t want to lose the power of study, so, this could be the reason for delay.”

Also, in the first interim results, Covaxin showed an efficacy of 81 percent while in the second it fell to 78 percent.

Based on how many were infected in the control group and placebo, the efficacy is reached, Dr Rao said.

WHO approval depends on data

The data is also needed for emergency use listing (EUL) from the World Health Organisation (WHO). The firm has submitted an expression of interest for EUL on April 19 to the WHO.

The vaccine maker will also be conducting Phase 4 trials of Covaxin to check its real-world effectiveness, the company said.

While the vaccine is yet to release final trial results on adults, clinical trials of Covaxin on children aged 12-18 are also being carried out at several centres of the country.

Experts say adolescents aged 2-17 years should not be part of any experiment until the vaccine’s protection in adults is fully established.

Most vaccine makers around the world have only released interim results of Phase 3 trials, which is why only an EUA has been given to vaccines, and the trials are still ongoing.