An initial study conducted by Coronavirus Vaccine-induced Antibody Titre (COVAT) showed Serum Institute of India’s Covishield vaccine producing more antibodies than Bharat Biotech’s Covaxin. Health workers who have received both shots of either of the vaccines participated in the study.
Compared to Covaxin, seropositivity rates to anti-spike antibody were much higher in Covishield after the recipients got their first dose, the study said. However, this hasn’t been peer-reviewed yet and is only a preprint. Hence, experts warned against using this to guide clinical practice.
Though Covishield and Covaxin generated a good response following administration of the first dose, Covishield showed a greater seropositivity rate and median anti-spike antibody content.
“Amongst the 552 HCW (325 Male, 227 Female), 456 and 96 received the first dose of Covishield and Covaxin respectively. Overall, 79.3 per cent showed seropositivity after the first dose. Responder rate and median (IQR) rise in anti-spike antibody were significantly higher in Covishield vs Covaxin recipient (86.8 vs. 43.8 per cent; 61.5 vs 6 AU/ml; both p<0.001),” the study said.
The HCW (healthcare workers) involved in the study were those got either of the 2 vaccines and with or without a positive history of SARS-CoV-2 infection. The study gained results based on the assessment after 4 weeks or more of the first dose and 6 months following the second jab.
“This ongoing, Pan-India, Cross-sectional, Coronavirus Vaccine-induced Antibody Titre (COVAT) study is being conducted amongst HCW, with or without past history of SARS-CoV-2 infection. SARS-CoV-2 anti-spike binding antibody is being assessed quantitatively at four time points between 21 days or more after the first dose to 6 months after the second dose,” the study further said.
Nevertheless, the response elicited by both Covishield and Covaxin was good, the study concluded saying.
“While both vaccines elicited immune response, seropositivity rates to anti-spike antibody were significantly higher in Covishield recipient compared to Covaxin after the first dose. Ongoing COVAT study will further enlighten the immune response between two vaccines after the second dose,” it added.