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

COVID-19 an infectious disease caused by the SARS-CoV-2 virus, started in late 2019 and became a pandemic within a short period. To respond to the pandemic vaccines like Covishield, Covaxin, Sputnik V, Covovax, etc., were developed rapidly. However, there were raising concerns about the development of immunity as well as adverse events following vaccination.