ABSTRACT
Introduction: COVID-19 has been declared as Public Health Emergency of International Concern with extreme risk of sustained global spread. The pandemic is likely to evolve in successive waves until herd immunity threshold (HIT) is achieved. Asymptomatic carriers and contacts are likely to elude case reporting through conventional algorithm of case finding, testing, contact tracing, and outbreak surveillance, thereby leading to underestimation of disease burden. Widespread community-level transmission of COVID-19 renders higher risk to health-care personnel due to higher propensity and duration of multiple exposures compared to general population. Methods: This is a cross-sectional clinicoepidemiological outcome surveillance study on prevaccination seroprevalence of COVID-19 immunoglobulin G (IgG) antibodies against S1 receptor binding domain in health-care personnel and general population. Results: Seroprevalence of COVID-19 IgG in 570 health-care personnel was 224/570 (39.3%), without any skew based on age or gender. 75% were exposed in the hospital while 21.2% were exposed during travel and 3.1% through high-risk contact outside the hospital. Out of 33 COVID-19 positives, 88% underwent hospital isolation including one ICU admission and 12 home isolation. Seroprevalence of COVID-19 IgG in 400 individuals from general population samples was 138/400 (34.5%). Conclusion: Prevaccination seroprevalence of COVID-19 IgG antibodies after the first pandemic wave revealed no significant difference among health-care personnel and general population reflecting upon a possibility of consecutive pandemic waves until community attainment of HIT. Seroepidemiology can be a robust tool essential to ascertain exposure, immune response, immunity status, and predict susceptibility in population cohorts.