A new comparative study has found that Covishield, manufactured by the Serum Institute of India, has shown better results in seropositivity than Covaxin, which has been manufactured by Bharat Biotech in India.
The study conducted by seven healthcare experts to compare the effects of the leading two vaccines being circulated in the country is currently undergoing a peer review. It was among the first research conducted by Indian healthcare experts to observe the immune responses in 515 healthcare officials after being inoculated with two shots of the vaccines. Its preprint published in an online medical archive called Medrxiv on June 2 showed that 98.1 per cent of the people who received Covishied produced antibodies and 80 per cent of those inoculated with Covaxin showed seropositivity.
The study conducted on 305 male and 210 female healthcare staff members confirmed that while both the vaccines are showing good results in terms of building antibodies, Covishield is marginally better than Covaxin.
The study also showed a good safety profile for both vaccines. The seropositivity rate was lower in recipients aged 60 years and above or those with type 2 diabetes, indicating a comparatively lower antibody response. On the other hand, there was no significant difference observed in relation to gender, body mass index, blood group and any comorbidities.
Another finding of the study revealed that there were only 2.2 per cent of positive cases of Covid-19 after two weeks of getting the first shot were lower in Covaxin recipients, while for Covishield a rate of 5.5 per cent. However, an important detail to note is that Covaxin recipients were lesser than Covishield in this study.
The study also compared the immune responses of participants with a history of Covid-19 and those who had never contracted the virus before. The analysis revealed that those recovered from Covid-19 at least six weeks before the first dose, and took both shots, were 100 per cent seropositive.
The lead author and scientist, Awadhesh Kumar Singh, Consultant Endocrinologist, G.D. Hospital and Diabetes Institute, Kolkata, also stated that the study used the phase 3 data published by Covishield, while the phase 3 data for Covaxin is not published yet.
"We could also produce some real-world evidence to show that Covaxin induces good protective antibodies after the two doses in the absence of published Phase 3 data at the moment. Covishield has already published its Phase 3 data," he said, as reported by The Print.
The scientists also acknowledged that the findings of the study do not necessarily predict efficacy. "While this study adds to the evidence, in the absence of measuring more specific neutralising antibody and other cell-mediated immunity response — it is difficult to comment whether one is superior to other. Only randomised head-to-head trial can conclude anything," the lead author added.