major Bharat Biotech on Wednesday said its Covid-19 vaccine, Covaxin, has demonstrated an interim vaccine efficacy of 81 per cent in the Phase 3 clinical trials.The trials involved 25,800 subjects, the largest ever conducted in India, in partnership with the Indian Council of Medical Research, the Hyderabad-based company said in a statement.Interim analysis also showed that severe, serious, and medically attended adverse events occurred at low levels and were balanced between vaccine and placebo groups, Bharat Biotech said.Today is an important milestone in vaccine discovery, for science and our fight against coronavirus. With today’s results from our Phase 3 clinical trials, we have now reported data on our Covid-19 vaccine from Phase 1, 2, and 3 trials involving around 27,000 participants.“Covaxin demonstrates high clinical efficacy trend against Covid-19 but also significant immunogenicity against the rapidly emerging variants,” said Dr Krishna Ella, Chairman and Managing Director, Bharat Biotech.In a press release, Bharat Biotech explained the way in which Covaxin works.“BBV152 contains a whole virion inactivated SARS-CoV-2 vaccine, which is produced in Vero cells. It is stable at 2 to 8°C (refrigerated) and is shipped in a ready-to-use liquid formulation that permits distribution using existing vaccine supply chain channels. BBV152 has a 28-day open vial policy as a unique product characteristic, thus reducing vaccine wastage by approximately 10-30%,” it