Covaxin shows 81% efficacy in phase-3 trials, says Bharat Biotech

President Ram Nath Kovind receives the first dose of vaccine during the second phase of inoculation Photo: PTI
Covaxin, India’s first indigenous Covid-19 vaccine to be approved has shown an interim efficacy of 81 per cent in its phase-3 clinical trial, Bharat Biotech said on Wednesday.

The AstraZeneca-Oxford vaccine has shown 62 per cent efficacy with two full doses, and 90 per cent efficacy in one half and one full dose regimen. Russian vaccine Sputnik V has shown a 91.6 per cent efficacy in interim  efficacy analysis data from 19,866 volunteers

Covaxin, co-developed by the Indian Council of Medical Research (ICMR) and Bharat Biotech, had been approved by the country’s drug regulator in clinical trial mode in January. The phase-3 studies involving over 25,800 subjects were underway at that time.

The approval had created a furor among the general public as well as the medical community. The government machinery had to spring into action to clear the air, with ICMR director general Balram Bhargava saying, “While phase three is still ongoing, immunogenicity data generated through phase two clinical trialserves as a surrogate for efficacy.”

Krishna Ella, the CMD of Bharat Biotech, had shown confidence in his product and said Covaxin has demonstrated 100 per cent results in animal challenge studies  (non-human primates), which means when exposed deliberately to the pathogen after vaccination, the animals did not get the disease.

Restricted use of Covaxin in clinical trial mode meant that beneficiaries will have to give consent and there will be regular follow up. Such persons will not receive the placebo.

Meanwhile, Bharat Biotech is gearing up to produce 40 million doses a month. Two Bio-safety Level-3 facilities (which can deal with deadly and contagious viruses) have been set up and the third one is on the way.

Interim Efficacy: 80.6%

The whole virion (virus) inactivated Covid-19 vaccine candidate has shown a vaccine efficacy of 80.6 per cent in a phase-3 study covering participants between 18-98 years of age. This included 2,433 people over the age of 60 and 4,500 with co-morbidities.

Bharat Biotech said, “The first interim analysis is based on 43 cases, of which 36 cases of COVID-19 were observed in the placebo group versus seven cases observed in the BBV152 (Covaxin) group, resulting in a point estimate of vaccine efficacy of 80.6 per cent.”

The interim analysis included a preliminary review of the safety database, which showed that severe, serious, and medically attended adverse events occurred at low levels and were balanced between vaccine and placebo groups. The trial's conduct and monitoring are as per Good Clinical Practice guidelines and have been outsourced to IQVIA.

Covaxin, which is stable at 2-8 degrees Celsius has also shown efficacy against the UK strain of the virus.

Ella has said that they can re-engineer their product in 15-days for other mutant strains once they have the isolated strain with them. “If ICMR isolates the South African strain, I can easily plug in the manufacturing accordingly and make a product from the South African strain in 15-days. Everything remains the same, one just has to switch the strain to get a new version of the vaccine,” he said recently.

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