Covaxin efficacy 78% in Phase 3 analysis
Covaxin, the coronavirus vaccine made by Bharat Biotech, has shown an efficacy of 78% in preventing symptomatic Covid-19 in the final phase 3 analysis, people familiar with the development said, adding that the vaccine maker is likely to announce the results in the beginning of June.
The comments come at a time when the vaccine maker has applied for approval from the World Health Organization, although it is yet to release any data from the phase 3 trials. The data will also need to undergo a peer review.
“The first interim efficacy analysis showed vaccine efficacy of nearly 81%, and the second interim analysis showed it to be about 78%. The final analysis was done at 130 confirmed case and it was found to be 78%,” said Dr Sanjay Rai, professor, community medicine department, All India Institute of Medical Sciences (AIIMS), Delhi.
“The interim analysis may be over, the analysed data needs to be peer-reviewed and published in a medical journal now,” added Rai, who is also the principal investigator of the study site at AIIMS.
The developments were also confirmed by an official concerned in the central government, aware of the matter.
“We have been made to understand that the interim analysis results for Covaxin phase 3 trials are almost done, and they are in the process of publishing the data,” the official said on condition of anonymity.
Scientists typically analyse vaccine efficacy at multiple, preset intervals -- known as endpoints. The first endpoint for Covaxin was when 43 cases were recorded, at which point the details of these individuals was unblinded. The result, announced in March, showed that 36 of these cases were in the placebo group while the rest, 7, were in the group given the vaccine, pointing to an efficacy estimate of 80.6%.
The second interim analysis result was released in April based on 87 symptomatic cases of Covid-19, and it showed that the efficacy against severe Covid-19 disease was 100%, with an impact on reduction in hospitalizations.
The full analysis is yet to be released, either a pre-print or as a peer-reviewed document.
While Bharat Biotech did not comment on the final analysis results, it did announce last month that the safety and efficacy results from the final analysis will be available in June, and the final report will be submitted to a peer-reviewed publication.
Experts, however, say the data should be put in public domain so that those experts in the field also get a chance to scrutinize it.
“Trial data should ideally be published in peer-reviewed top medical journal so that those people who are not a part of the clinical trial can study it, question it and cross-check the legitimacy of the trial,” said CM Gulhati, editor, Monthly Index of Medical Specialities (MIMS), pharmaceutical reference guide.
The phase 3 study enrolled 25,800 participants between 18-98 years of age, including 10% over the age of 60, with analysis conducted 14 days post second dose. Covaxin was developed with seed strains received from the National Institute of Virology under the Indian Council of Medical Research.