Serosurveillance of Post vaccination SARS-CoV-2 antibodies in Covishield and Covaxin Vaccinated Subjects

Background: Whole virion (attenuated) vaccine (Covaxin) and m-RNA of whole Spike protein (Covishield) were used as emergency measures in SARS-CoV-2 infection. Aim & Objective: To evaluate the antigenicity of both vaccines by measuring the quantum of antibodies. Methods and Material: Periodic antigenicity of both the vaccines post-vaccination i.e. after 5-6 and 11-12 months was undertaken in two categories; those who were not infected and vaccinated and secondly infected and vaccinated and got re-infected (after vaccination). Results: Both the categories of patients showed similar quantum of IgA/IgG/ IgM and Neutralizing antibodies generated by Covaxin. In subjects, vaccinated by Covishield, the recipients of single dose of vaccine showed higher titre of antibodies than double dose vaccinated. Less antigenicity of Covishield vaccine in infected vaccinated was seen compared to un-infected vaccinated subjects. Conclusions: Paper reports antigenic strength of both the vaccines during 5-6 and 11-12 months’ post-vaccination and also the important point that antibodies titre was higher among cohort of single vaccinated as compared to those who received two doses of vaccines. The paper further sensitises the issue that both the vaccines were developed on the Wuhan strain whereas the virus has mutated twice, generating two new subsequent strains namely Delta and Omicron.