Phase I and II trial data for India’s homegrown, government-backed Covid-19 vaccine, Covaxin (BBV152), has been published in The Lancet Infectious Diseases.

The publication of the study comes a week after Hyderabad-based vaccine manufacturer Bharat Biotech, developer of Covaxin, presented analysis of Phase III results for the vaccine, suggesting an interim efficacy of 81% in preventing Covid-19 in individuals without prior infection after two doses.

The Phase I/II results were presented on Tuesday in a study titled ‘Safety and immunogenicity of an inactivated SARS-CoV-2 vaccine, BBV152: interim results from a double-blind, randomised, multicentre, phase 2 trial, and 3-month follow-up of a double-blind, randomised phase 1 trial’.

The study found that Covaxin is “safe, immunogenic with no serious side effects”, with high neutralising antibody responses that were sustained after the three-month follow-up to the Phase I trial.

The Lancet-published study reported preliminary analyses for the immunogenicity and safety of BBV152 in 380 vaccinated adults and adolescents. “BBV152 led to enhanced immune responses and induced T-cell responses that were biased to Th1,” the study noted. “Due to the difference in dosing regimens between phase 1 (two doses given 2 weeks apart) and phase 2 (two doses given 4 weeks apart) trials, neutralisation responses were significantly higher in the phase 2 trial than in the phase 1 trial.”

The study also reported that the number of participants with adverse events was significantly lower in the Phase II trial than in Phase I.

The randomised, double-blind, multicenter, phase 2 trial evaluated the safety and immunogenicity of Covaxin in healthy adults and people between the ages of 12 and 65 at nine hospitals in India. According to the researchers, the most common adverse events in the Phase II trial was pain at the injection site, headache, fatigue and fever.

No life-threatening adverse events were reported in the trial.

The study findings also showed that no immunological differences were observed between men and women and across age groups. Both groups that received the vaccine had similar outcomes.

Speaking at a conference of the Confederation of Indian Industry, Bharat Biotech’s co-founder and managing director Suchitra Ella said: “What started as an initiative driven by government institutions four to five decades ago, with significant participation of Indian research institutions for basic vaccines, has now grown to become a big industry with India accounting for 60-65% of global supplies of vaccines and Hyderabad accounting for about 70% of India’s vaccine manufacturing capability.”

“Even for the supply of Covid-19 vaccines, in India there are six major companies that are engaged in manufacture. India will, therefore, play a significant role and probably account for around the same volumes of other vaccines,” she continued.

India’s regulators granted emergency approval to Covaxin in January when Phase III trials were still underway, sparking concern and scepticism from some in the industry. But preliminary data from the Phase III trial has now validated the positive efficacy rates reported in earlier-stage trials.

In January, Prime Minister Narendra Modi commented: “Today, when we’ve developed our own vaccine, the world is looking at India with hope. As our vaccination drive will move forward, other countries of the world will benefit from it. India’s vaccine and our production capability must be used for human interest, this is our commitment.”