According to a preliminary study conducted by Coronavirus vaccine-induced Antibody Titre COVAT) involving healthcare workers (HCW) who have received both doses of either of the two vaccines it is found that the Covishield vaccine produced more antibodies than Covaxin.
The study claimed that seropositivity rates to anti-spike antibody were significantly higher in Covishield recipients compared to Covaxin after the first dose.
It is a preprint study that has not been peer-reviewed hence it should not be used to guide the clinical practice. However, it is said that both the vaccines Covishield and Covaxin, elicited a good response after two doses but seropositivity rate and median anti-spike antibody were significantly higher in Covishield.
“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.
“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 timepoints between 21 days or more after the first dose to 6 months after the second dose,” the study said.
However, the conclusion of the study said that both the vaccines have elicited good immune response.
“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 said.
For the study, 515 healthcare workers from 13 States and covering 22 cities were evaluated from January to May 2021. Their 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.
The study found that a single dose of Covishield elicited about 10 times the antibodies than Covaxin whereas a second dose narrowed the gap somewhat with Covishield-triggered antibodies about six times that of Covaxin-stimulated ones.
“Contrarily, Covishield showed a good seropositivity rate and a 4-fold rise in median antibody titre even after a single dose,” the authors note. It is important to note that of the 515, only 90 got Covaxin and overall, 97.8% of those who never had COVID and had two complete doses of Covishield had detectable levels of antibodies, or tested seropositive, compared to 79.3% with Covaxin.
Covishield constitutes an irresistible majority of vaccines administered in the country with nearly nine persons getting it for every one of Covaxin.