The study, yet to be peer-reviewed, is based on data from 515 healthcare workers. (File)
Covaxin-maker Bharat Biotech's Raches Ella's post objecting to a study that compares the immune response of the two vaccines used in India led to an interesting exchange on Twitter on Monday.
The widely reported pre-print study said while both vaccines showed a good immune response after two doses, the Serum Institute of India's Covishield produced more antibodies than Covaxin.
The study, yet to be peer-reviewed, is based on data from 515 healthcare workers who received both doses of either of the two vaccines.
Raches Ella, head of business development and advocacy at Bharat Biotech, questioned in tweets why "non-peer-reviewed work" was put out.
"Surprised that media/researchers are concluding based on non-peer-reviewed work. Limitation 1: Spike-based IgG's are not appropriate when evaluating Covaxin, which induces broad antibody responses to Spike, N, and M. Recommend live virus neutralization," Mr Ella tweeted, responding to a newspaper headline.
"Limitation 2: Past history of Covid was based on verbal response and not by a pre-vaccination IgG test. The study fails to account for asymptomatics (predominant presentation of Covid) and introduces misclassification bias. SARS-CoV-2 naive participants may not be naive after all," he posted in his thread.
"The Lancet recommends authors refrain from actively seeking media attention for articles that are not peer-reviewed. If contacted by the press, authors clearly need to state these are preliminary findings that have not been peer-reviewed," Mr Ella added.
One of the doctors involved in the study, AK Singh, then posted a sharp retort referring to Covaxin jabs being given to people in India while still in trial stages.
"Brother, whole country is getting vaccinated even without a preprint phase 3 results - lest forget published one. We owe a sincere gratitude to Bharat Biotech but that doesn't mean one should raise finger on others effort. Of course we will produce published results finally!" - Dr Singh wrote.
To which, Mr Ella replied: "Not raising fingers, merely citing limitations that have a bearing on the study outcome. Salute your efforts as well. Phase 3 will be out very soon."
Covaxin was cleared for use "in public interest" for the Centre's vaccination drive amid much controversy over the fact that its late-stage trial data was not available.
In April, Bharat Biotech and the government's top medical body ICMR claimed that Covaxin had shown overall interim effectiveness of 78 per cent and was 100 per cent effective against severe Covid.
Bharat Biotech said last month that it expected its application for WHO approval to be accepted in July-September. The company said it had submitted "90 per cent of the documentation required" for WHO authorization and would deliver the remaining in June.