Covishield produced more antibodies than Covaxin, claims a preprint of the first Indian study involving doctors and nurses who received both doses of either of the two COVID-19 vaccines. The study conducted by Dr. AK Singh, Consultant Endocrinologist, GD Hospital & Diabetes Institute, Kolkata, and his colleagues states that the response received from both vaccines was good.
The data which is yet to be published had earlier indicated that Covishield was found to be 70 percent effective after the first dose. Covaxin’s preliminary data from its phase 3 trial had suggested an efficacy rate of 81 percent. "Among 515 healthcare workers (305 male, 210 female), 95 percent showed seropositivity (higher antibodies) after two doses of both vaccines. Of the 425 Covishield and 90 Covaxin recipients, 98.1 percent and 80 percent, respectively, showed seropositivity," says the study.
The study shows that both Covishield and Covaxin prompted a good immune response after two doses. The Covishield arm had significantly higher seropositivity rates and median anti-spike antibody titer as compared to the Covaxin arm. An antibody titer is a type of blood test that determines the presence and level (titer) of antibodies in the blood and is denoted in 115 AU/ml (arbitrary units per milliliter). The antibody titer for Covishiled was 115 AU/ml, while for Covaxin it was 51 AU/ml.
As per the study, a total of 27 breakthrough infections (4.9 percent) were recorded among respondents who had received both doses of either of the vaccines. 25 out of the 27 were mild infections and two were moderate cases of breakthrough infections. These infections didn’t lead to the death of any of the respondents. The risk of breakthrough infections in the case of Covishield is 5.5 percent, while for Covaxin it is 2.2 percent. While there was no difference observed in the respondents regarding gender, body mass index, blood group, and any comorbidities, people aged 60 years and above or those with type 2 diabetes had a significantly lower seropositivity rate, indicating a comparatively lower antibody response.