Covaxin phase 2 data shows vaccine safe, induces immune response: Lancet Study

The latest study comes a week after Bharat Biotech announced that the vaccine has shown 81 per cent efficacy in the third phase of clinical trials

Two intramuscular doses of vaccine were administered on day 0 and day 28. Credit: Reuters Photo

Bharat Biotech's Covaxin has shown better safety and enhanced immune responses in the vaccine's Phase-2 clinical trial results, medical journal Lancet said in its study

The Hyderabad-based company last week announced that its vaccine demonstrates 81 percent efficacy in preventing Covid-19. Bharat Biotech's interim projections were based on Covaxin's Phase-3 trials.

Covaxin, developed by Bharat Biotech and ICMR-National Institute of Virology, is part of the ongoing Covid-19 immunization drive in the country.

Lancet had published the Phase-1 trial results in January. The interim report then said that Covaxin affected enhanced immune responses against Covid-19.

Read more: Brazil company requests emergency authorisation to use Covaxin

In the phase 1 trial, BBV152 or Covaxin induced high neutralising antibody responses that remained elevated in all participants at three months after the second vaccination.

“In the phase 2 trial, BBV152 showed better reactogenicity and safety outcomes, and enhanced humoral and cell-mediated immune responses compared with the phase 1 trial,” the report whose contributors include Bharat Biotech CMD Krishna Ella, and ICMR Director General Balram Bhargava and others said.

The phase-2 trials of the indigenously developed vaccine were conducted in September for which 921 potential participants were screened. 380 of them enrolled andrandomly assigned into two groups - 3 μg with Algel-IMDG group (n=190) or 6 μg with Algel-IMDG group (n=190).

The Lancet Infectious Diseases paper, published on Monday, said that the 6 μg with Algel-IMDG formulation has been selected for the phase 3 efficacy trial.

The report said that the proportion of participants reporting adverse events in the phase 2 trial were lower than in the phase 1 trial.

The most common adverse event in the phase 2 trial was pain at the injection site, followed by headache, fatigue, and fever. No severe or life-threatening adverse events were reported.

“Further corroboration with phase 3 safety results is required. The study enrolled a small number of participants aged 12–18 years and 55–65 years. Follow-up studies are required to establish immunogenicity in children and in those aged 65 years and older,” the Lancet publication said.

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