Post-vaccine immune status surveillance of Covishield vaccine and associated AEFI in previously SARS-Cov-2 infected seropositive and seronegative population in Assam.

dose (booster dose). Antibody titres of the seropositive group by natural infection of SARS-CoV-2 were higher than seronegative cohort seroconverted by vaccination. The AEFI observed were minor and can be commented as safer.