ABSTRACT
Background: With reference to the National vaccination drive against COVID-19 disease (rolled out on January 16, 2021 by Government of India), this study was undertaken to analyze the patterns of antibody response among fully vaccinated adult individuals, to find the spectrum of adverse events following immunizations and knowledge component of the participants regarding the COVID-19 vaccines as well as its side effects. Materials and Methods: A total of 500 vaccinated individuals (with two doses of Government approved Covishield vaccine) were studied over a period of 9 weeks following the second dose of their vaccine. They were tested for the development of antibodies against SARS-CoV-2 spike protein, using an immunoglobulin G ELISA kit on three occasions, and the seroconversion pattern was analyzed. Results: A postvaccination seroconversion rate of 63.8% (at 2-3 weeks), 83.2% (at 4-5 weeks), and 93.2% (overall seroconversion rate at 8-9 weeks) was found. While 77.4% participants (at 4 weeks) and 65.9% participants (at 8 weeks) showed rise in optical density (OD) values, 7.4% showed a declining in OD values (at 8 weeks) and 6.8% remained seronegative throughout the study period. Sixty-two percent had experienced at least one form of adverse effect postvaccination, which were mostly mild in nature not requiring hospitalization. Conclusion: This study found that the timeline for seroconversion postvaccination by COVISHIELD varies between individuals, with few showing decline in the OD values as well and that majority of the adverse reactions observed in this population were only mild and manageable not requiring hospitalization.