Blood samples were also tested for the presence, quantity of antibodies produced and levels of the specific antibodies that are directed to the spike protein of the virus, widely held to be a proxy of protection.
“Of the 425 Covishield and 90 Covaxin recipients, 98.1% and 80.0% respectively, showed seropositivity,” said the study, adding that the “median interquartile rise” in anti-spike antibodies was also “significantly higher in Covishield vs Covaxin recipient” at 127 AU/mL and 53.0 AU/mL respectively.
Study compared post-vaccination immune responses of participants with a history of COVID-19, and those who didn’t. It found that participants who had recovered from COVID-19 at least six weeks before the first dose, and took both shots, were 100 per cent sero positive and had higher antibody titres, too.
“Both vaccines showed good and similar immune responses even after a single dose in people who already had Covid in the past. This suggests both vaccines work well,” said Awadhesh Kumar Singh, lead author of the study and consultant endocrinologist, G.D. Hospital and Diabetes Institute, Kolkata.
“It, however, appears that Covishield may have a greater ability to produce more anti spike antibodies and higher seropositivity rate,” he added.
“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.”
On whether the study measured vaccine efficacy beyond antibodies, the lead author told ThePrint: “While this study adds to evidence, in the absence of measuring more specific neutralizing 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.”
Source: Medindia
