Covaxin is a highly purified and inactivated 2 dose SARS-CoV2 vaccine, manufactured in a Vero cell manufacturing platform with an excellent safety track record of more than 300 million doses, the Hyderabad-based company said in a statement.
"The evaluation of Covaxin has resulted in several unique product characteristics including long term persistence of immune responses to multiple viral proteins, as opposed to only the spike protein, and has demonstrated broad spectrum neutralising capability with heterologous SARS-CoV2 strains, thus potentially reducing or eliminating escape mutants," it said.
"It has also shown to generate memory T cell responses, for its multiple epitopes, indicating longevity and a rapid antibody response to future infections. Its most critical characteristic is the demonstrated safety profile, which is significantly lower than several other vaccines with published data," it added.
DCGI has come under flak from various quarters for approving Covaxin even before the completion of Phase 3 trials. Critics wondered how the regulator could approve the vaccine in the absence of the data from Phase 3.
The DCGI's approval to Covaxin came a day after the Subject Expert Committee of Central Drugs Standard Control Organisation (CDSCO) made the recommendation.
Bharat Biotech said it submitted all the data to the DCGI and CDSCO as per the regulatory guidelines.
The product development and clinical trial data thus far has generated 5 publications, which have been submitted to international peer reviewed journals, 4 of which have been accepted and will be published soon. The publication of Phase 2 trial data is undergoing the peer review process, the company said.
The DCGI stated that Bharat Biotech generated safety and immunogenicity data in various animal species. "All these data has been shared by the firm with CDSCO. Phase 1 and Phase 2 clinical trials were conducted in approx 800 subjects and the results have demonstrated that the vaccine is safe and provides a robust immune response. The Phase 3 efficacy trial was initiated in India in 25,800 volunteers and till date, 22,500 participants have been vaccinated across the country and the vaccine has been found to be safe as per the data available till date," the regulator said.
"The Subject Expert Committee (SEC) has reviewed the data on safety and immunogenicity of the vaccine and recommended for grant of permission for restricted use in emergency situation in public interest as an abundant precaution, in clinical trial mode, to have more options for vaccinations, especially in case of infection by mutant strains. The clinical trial ongoing within the country by the firm will continue," it added.
India's indigenous Covid vaccine by Bharat Biotech has been developed in collaboration with the Indian Council of Medical Research (ICMR) - National Institute of Virology (NIV).
It is inactivated intramuscular vaccine that works by injecting the inactivated version of Sars-Cov-2, the virus which causes Covid-19, into the body to develop an immune response.
According to the vaccine maker, Covaxin has been evaluated in approximately 1000 subjects in Phase 1 and Phase 2 clinical trials, with promising safety and immunogenicity results, with acceptance in international peer reviewed scientific journals.
The Phase 3 human clinical trials of Covaxin began mid-November, targeted to be done in 26,000 volunteers across India. This is India's first and only Phase 3 efficacy study for a Covid-19 vaccine, and the largest Phase 3 efficacy trial ever conducted for any vaccine in India.
This indigenous, inactivated vaccine is developed and manufactured in Bharat Biotech's BSL-3 (Bio-Safety Level 3) bio-containment facility, one of its kind in the world, said Bharat Biotech Chairman and Managing Director Dr Krishna Ella.
It was in June that Bharat Biotech had announced that it successfully developed Covaxin in collaboration with the ICMR and the NIV.
The SARS-CoV-2 strain was isolated in NIV, Pune and transferred to Bharat Biotech.
The Phase 1 trials began in July while Phase 2 trials started in September.
Sai Prasad, Executive Director, Bharat Biotech had told IANS in November that Covaxin was found to be safe without any major adverse events in the first two stages of the trials.
"We follow a well-designed vaccine development protocol, and ensure each stage of our vaccine development is driven with a sole goal to attain a strong immune response rate in our clinical trials. When we do a trial design, we take into account the attack rates, the disease type, the ability of us to detect the disease and then the recruitment timelines," the official had said when asked about the comparison with vaccines being developed by several companies around the world.
The company has already built capacities to manufacture 200 million doses of vaccine and plan to further enhance to 500 million doses.
It is investing about Rs 350-400 crore for the development of vaccine and the new manufacturing facilities, which includes investments for conducting the Phase 3 trials.