NEW DELHI :
The study also found that seropositivity rate was “significantly more” in participants with an age of 60 or less compared to those above 60
THE Covishield vaccine produces more antibodies than Covaxin though both generate a “good immune response”, says a pan-India study of healthcare workers who had received both doses of the preventives. The yet-to-be-published study, posted on the preprint repository MedRxiv on June 4, covered 515 healthcare workers (HCW) -- 305 men and 210 women -- from 22 cities in 13 States. Covishield, from the Oxford-AstraZeneca stable, is manufactured by the Serum Institute of India in Pune. Covaxin is the indigenously manufactured vaccine by Hyderabad-based Bharat Biotech in collaboration with ICMR and National Institute of Virology (NIV).
The blood samples of those participating in the study were tested for the quantity of antibodies produced and levels of specific antibodies that are directed to the spike protein of the virus, which is regarded as a proxy for protection. “Both vaccines elicited good immune response after two doses, although seropositivity rates and antibody levels were significantly higher in Covishield compared to Covaxin,” Awadhesh Kumar Singh, lead author of the study and consultant endocrinologist, G D Hospital and Diabetes Institute, Kolkata, said in a tweet. Seropositivity was observed in a higher number of people vaccinated with Covishield as compared to those immunised with Covaxin. “Among the 515 HCW, 95 per cent showed seropositivity after two doses of both vaccines. Of the 425 Covishield and 90 Covaxin recipients, 98.1 pc and 80 per cent respectively, showed seropositivity,” said study authors. Seropositivity refers to the production of antibodies in an individual.
The rise in anti-spike antibodies was also “significantly higher in Covishield vs Covaxin recipient” at 127 absorbance units per milliliter (AU/mL) and 53 AU/mL respectively, the authors noted. Apart from finding higher seropositivity among Covishield recipients, the study found that seropositivity rate was “significantly more” in participants with an age of 60 or less compared to those above 60. While factors such as gender, body mass index (BMI) and other comorbidities didn’t make any difference, the seropositivity rate or antibodies in people with type 2 diabetes was found to be significantly lower. The researchers also compared the post-vaccination immune responses of all participants with those who had 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 of both vaccines, and later took both shots, were 100 pc seropositive, and had higher antibody levels compared to others.