NEW DELHI: In an encouraging development for India's vaccination drive, leading UK medical journal The Lancet on Tuesday said that indigenously developed Covaxin was found to be safe and has demonstrated better performance in the Phase 2 trials compared to Phase 1.

The report, released today, said that the vaccine developed by Hyderabad-based Bharat Biotech showed better reactogenicity and safety outcomes, and enhanced humoral and cell-mediated immune responses compared with the Phase 1 trials.

It comes just days after Bharat Biotech and Indian Council of Medical Research (ICMR) announced that Covaxin demonstrated nearly 81% efficacy in interim Phase 3 trials.

Here's all you need to know:

No Adverse Events

The paper said that 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 solicited adverse events were reported. No significant differences in safety were observed between the two groups," it said.

'Better Reactogenicity And Safety Outcomes'

According to the journal, in the phase 1 trial, BBV152 (Covaxin's codename) induced high neutralising antibody responses that remained elevated in all participants at 3 months after the second vaccination.

"In the phase 2 trial, the Bharat Biotech vaccine showed better reactogenicity and safety outcomes, and enhanced humoral and cell-mediated immune responses compared with the phase 1 trial," it said.

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

'Further Corroboration Needed'

The paper, however, said that the efficacy of the vaccine cannot be determined by Phase 2 trials and needs to be corroborated further with Phase 3 results.

"The results reported in this study do not permit efficacy assessments. The evaluation of safety outcomes requires extensive Phase 3 clinical trials. We were unable to assess other immune responses (ie, binding antibody and cell-mediated responses) in convalescent serum samples due to the low quantity. Furthermore, no additional data on the age of the participant or the severity of disease from symptomatic individuals were obtained," it said.

It also pointed out that comparisons between phase 1 and 2 trials were not done in a randomised set of participants, and no adjustments on baseline parameters were made.

"Conclusions are to be considered as post-hoc analyses. Even though direct comparisons between the phase 1 and 2 trials cannot be made, the reactogenicity assessments reported in this study were substantially better in the phase 2 trial than the phase 1 trial and other trials with a placebo group," it added.