Hyderabad-based firm Bharat Biotech criticised a recently released comparative report evaluating the antibody response of its COVID-19 vaccine Covaxin with Serum Institute-manufactured Covishield on Wednesday, 9 June, saying that it had “lots of flaws.”
It stated that in comparison with Covaxin, Covishield shows a significantly higher seropositivity rate and antibody response against the spike protein.
In a statement to news agency ANI, Bharat Biotech said, “A recent comparative report on evaluation of immunogenicity responses to spike protein after first and second dose of Indian manufactured vaccines study had lots of flaws.”
The vaccine manufacturer pointed out that the study was not “peer-reviewed or statistically and scientifically designed” and thus, demonstrates an “an ad hoc analysis, rather than predetermined hypothesis.”
The statement also said that the study was not registered on CTRI website, nor approved by Central Drugs Standard Control Organisation (CDSCO) and the Subject Expert Committee (SEC).
Dr Raches Ella, Project Lead of COVID-19 Vaccines at Bharat Biotech, the makers of Covaxin, too, called out the coverage given to the study on Twitter and said, "Spike-based IgG's are not appropriate when evaluating Covaxin, which induces broad antibody responses to Spike, N, and M. Recommend live virus neutralization."
Bharat Biotech further said, “It is critical to understand the Phase-3 data will first be submitted to CDSCO, followed by peer reviewed journals, with a timeline of ~ 3 months for publication, and as communicated earlier COVAXIN phase 3 results full trial data will be made public during July.”
Only after the data from the final analysis of phase three studies is made available, will the firm apply for full licensure for COVAXIN.
The Study
Data of 515 vaccinated healthcare workers, across 21 cities in 13 states, was analysed from across India between January and May 2021. Among them, 425 HCWs had taken Covishield and 90 Covaxin.
It found that 95 percent of the participants showed seropositivity after the two doses of both vaccines.
“Of the 425 Covishield and 90 Covaxin recipients, 98.1 percent and 80 percent respectively, showed seropositivity. However, both seropositivity rate and median (IQR) rise in anti-spike antibody was significantly higher in Covishield vs Covaxin recipient,” it added.
However, according to Dr Gagandeep Kang, who is a microbiologist from Christian Medical College in Vellore, when vaccine companies develop vaccines, you can't do a direct comparison of one vaccine and another because the tests to measure immune responses are different.
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