Covaxin submits Phase 3 data to expert panel, claims 78% efficacy

The efficacy rate is similar to interim trial analyses, but the company is yet to release data regarding the multiple analyses it has carried out at different points in time.

Covaxin, the coronavirus vaccine by Bharat Biotech, has shown a 77.8% efficacy in preventing symptomatic Covid-19 in large scale clinical trials, according to the data shared with Indian drug regulators who analysed the findings, an official aware of the matter said on Tuesday.

Bharat Biotech is yet to release the data from any of the interim analyses of the clinical trials.(HT Photo)

The efficacy rate is similar to interim trial analyses, but the company is yet to release data regarding the multiple analyses it has carried out at different points in time. The trial was carried out in 25,800 volunteers and the latest data set was submitted to the Subject Expert Committee (SEC) of the Central Drugs Standards Control Organisation (CDSCO) over the weekend.

“The required data was submitted by the company, and the subject expert committee went though it today. The experts were satisfied with the results presented, and the vaccine efficacy is confirmed at 77.8%,” said an official in the government aware of the development, on condition of anonymity.

The vaccine was approved for emergency use in the Indian population in January, and the Hyderabad-based company had then said it would release phase III data by March. The release has since been pushed back on several occasions.

There were no delays in the company releasing its Phase 3 trial data, and that the progress was as per schedule, a company executive, Bharat Biotech, said.

“Regulators want a minimum of two months data after the last trial participant is jabbed for efficacy analysis. The last participant in the trial of 25,800 participants was jabbed around mid-May; therefore the analysis will take its time. Hundreds of people are on job to analyse 2-3 lakh data sheets and some 50 lakh data points. We already have 9 papers published in top notch peer-reviewed publications; we have been totally transparent with our data,” the executive added.

Clinicians said the efficacy results disclosed on Tuesday were encouraging. “No vaccine is going to be 100% effective but then for respiratory diseases it is anyway not possible to have 100% efficacy. Anything above 60% is good enough for a vaccine against a respiratory infection,” said Dr GC Khilnani, former head of the pulmonology and sleep medicine department, All India Institute of Medical Sciences, Delhi.

However, Bharat Biotech is yet to release the data from any of the interim analyses of the clinical trials. Concerns over lack of data trace back to January when the vaccine was approved by the Drugs Controller General of India under what it then said was in “clinical trial mode”. At the time, the company was yet to determine the efficacy rate.

The first analysis -- based on 43 cases -- came in March, when it reported an 81% efficacy. This number came to about 78% in the second interim analysis, the results of which was disclosed on April 21 based on infections in 87 people.

The Hyderabad-based company is also expected to hold a “pre-submission” meeting this week with the World Health Organization on Wednesday for emergency use listing of its vaccine. A WHO listing will help the vaccine being recognized by more agencies and countries, and potentially help the validity of vaccine certificates of people who got the dose.

Clinical trials of Covaxin are also being carried out in children and have had a huge response. At present, participants in the 6-12 years age category are being recruited. The company has approval to conduct trial in children between 2 and 18 years.

“We are unable to handle all the requests that are coming from parents, and even doctors, who want their children to receive the shot as part of the trial,” said the company executive.

Covaxin is one of the three vaccines which are currently being used in India. The vaccine is based on an inactivated virus platform, and its efficacy rate may be among the best in vaccines that use the same technique. China uses two vaccines on the same platform – made by Sinopharm and Sinovac. The Sinovac vaccine has been approved by the WHO but officials in China have since expressed concerns that its efficacy rate – between 51%-67% -- may be too low.

Even vaccines with lower efficacy rates, however, are believed to offer significant protection from hospitalisation and death.

Covaxin accounts for a little over 10% of the close to 290 million doses of coronavirus vaccines delivered in India.