Bharat Biotech’s Covaxin vaccine has demonstrated 81 per cent efficacy in preventing Covid-19 in those without prior infection after the second dose during its phase III clinical trials and also offers significant immunogenicity against the rapidly emerging variants, including the UK strain, the company said on Wednesday.

The company issued a statement at the end of phase III trials of the vaccine involving 25,800 subjects, the largest ever conducted in the country in partnership with the Indian Council of Medical Research.

Covaxin had been dragged into a controversy after it was granted emergency authorisation in the country before it completed phase III clinical trials.

On Monday, while flagging off the country’s vaccination drive for the general public Prime Minister Narendra Modi had opted for the indigenously developed Covaxin.

According to Bharat Biotech, Covaxin is based on an established manufacturing platform with a better safety profile when compared to other vaccine platforms and also offers long term protection.

Chairman and managing director of Bharat Biotech, Dr Krishna Ella, said: “With today’s results from our phase III clinical trials we have now reported data on our Covid-19 vaccine from Phase I, II and III trials involving around 27,000 participants. Covaxin demonstrates high clinical efficacy trend against Covid-19 but also significant immunogenicity against the rapidly emerging variants.”

Analysis from the National Institute of Virology indicated that the vaccine- induced anti-bodies can neutralize the UK variant strains and other heterologous strains.

The phase III trial held at 25 centres across the country had enrolled 25,800 participants between the ages of 18 and 98 including 2433 over the age of 60 and 4500 with co-morbidities. 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. The trial was conducted by a third party, a multinational company IQVIA, said Dr Ella, and ethical committee members monitored each of the 25 test centres adhering to Good Clinical Practice guidelines.

Dr Ella said the rest of the data will be shared in public domain through submission to a peer reviewed journal for publication. More than 40 countries in the world have expressed their interest in Covaxin, said the company.

The vaccine is stable between 2 and 8 degree C when refrigerated and is shipped in a ready to use liquid formulation that permits distribution using existing vaccine supply chain channels. Moreover it has 28 days open vial policy thereby reducing vaccine wastage approximately by 10-30 per cent, the company said.