Covaxin demonstrates 77.8% efficacy against symptomatic Covid-19 and 93.4% against severe disease, Bharat Biotech has concluded in the final analysis of the efficacy of the vaccine from phase 3 clinical trials published in a pre-print study.
"Efficacy analysis demonstrates Covaxin to be 77.8% effective against symptomatic Covid-19, through evaluation of 130 confirmed cases, with 24 observed in the vaccine group versus 106 in the placebo group. Efficacy analysis demonstrates Covaxin to be 93.4% effective against severe symptomatic Covid-19," said the yet to be peer-reviewed study paper published in open access journal medRxiv.
Safety analysis of the data also demonstrates adverse events reported were similar to placebo, with 12% of subjects experiencing commonly known side effects and less than 0.5% feeling serious adverse events.
According to the study, efficacy data of the whole virion inactivated vaccine further demonstrates 63.6% protection against asymptomatic disease, and 65.2% protection against the Sars-Cov-2, B.1.617.2 Delta variant.
Phase 3 clinical trials was an event-driven analysis of 130 symptomatic Covid-19 cases, reported at least two weeks after the 2nd dose. They were conducted at 25 sites across India.
Covaxin is formulated with a novel Algel+IMDG adjuvant, which is a TLR7/8 agonist known to induce memory T cell responses along with strong neutralising antibodies.
The activation of cell-mediated immune responses is especially valuable in a multi-epitope vaccine such as Covaxin, where immune protection can be achieved from S, receptor-binding domain, and N proteins alike.
The vaccine was well-tolerated, and the Data Safety Monitoring Board has not reported any safety concerns related to the vaccine. The overall rate of adverse events observed in Covaxin was lower than that seen in other Covid-19 vaccines.
The company said the safety profile of Covaxin is now well established based on inactivated vaccines technology, and in large part due to the extensive 20-year safety track record of Bharat Biotech's vero cell manufacturing platform.
It added that it has so far not sought indemnity for Covaxin from the governments.
"The successful safety and efficacy readouts of Covaxin as a result of conducting the largest ever Covid vaccines trials in India establishes the ability of India and developing world countries to focus towards innovation and novel product development. We are proud to state that innovation from India will now be available to protect global populations," said Krishna Ella, chairman, and managing director, Bharat Biotech, in a statement.
The company said Covaxin has been specifically designed to meet the needs of global distribution chains, the requirements for which are more critical in low- and middle-income countries. It has been formulated to enable shipping and long-term storage at 2-8ºC.
The company said Covaxin is also formulated to adhere to a multi-dose vial policy, thereby reducing open vial wastage, saving money to procurement agencies and governments alike.
Balram Bhargava, the director-general of the Indian Council of Medical Research (ICMR), said, "I am delighted to note that Covaxin developed by ICMR and BBIL under an effective public-private partnership has demonstrated an overall efficacy of 77.8% in India's largest Covid phase 3 clinical trial thus far. I am also pleased to see that Covaxin works well against all variant strains of SARS-CoV-2. The successful development of Covaxin has consolidated the position of Indian academia and industry in the global arena."
Bharat Biotech now has 10 publications on Covaxin, covering all aspects of product development in the past year.
Additional clinical trials are ongoing to establish safety and efficacy in the 2-18 age group. A clinical trial to determine the safety and immunogenicity of a booster dose is also in process. Apart from that several research activities are being carried out to study variants of concern and to assess their suitability for follow-up booster doses.
Covaxin has been evaluated through neutralising antibody responses against several variants of concern--B.1.617.2 (Delta), B.1.617.1 (Kappa), B.1.1.7 (Alpha), B.1.351 (Beta), P2- B.1.1.28 (Gamma). The data from these studies have been published in peer-reviewed journals and available for review.
"The overall efficacy of 77.8 % following the phase III clinical trial of Covaxin is wonderful news. Sera from Covaxin recipients have also been evaluated against viral variants detected in India ie the Alpha, Beta, Zeta, Kappa, and Delta. The making of this vaccine entirely on Indian soil is a matter of great pride to every Indian," said Priya Abraham, director, National Institute of Virology.
The vaccine has received emergency use authorisations in 16 countries including, Brazil, India, the Philippines, Iran, Mexico.