Immunoglobulin-G Antibodies against Severe Acute Respiratory Syndrome – Coronavirus-2 among Health-Care Workers: A Serosurveillance Study from India

Background: Seropositivity among health-care workers (HCWs) may help in better understanding of the immune response after COVID-19 infection. Objectives: To estimate seropositivity among HCWs and to compare available variables with seropositivity to understand the factors affecting seropositivity. Materials and Methods: A serosurveillance among HCWs was carried out using population proportion sampling during the second half of October 2020 in the city of Ahmedabad using the Covid-Kavach (immunoglobulin G [IgG] ELISA Antibody testing kit). Simple proportions and appropriate statistical tests were used as needed. Results: As on October' 2020, HCWs in Ahmedabad demonstrated a seropositivity of 20.84% (95% confidence interval [CI] 19.00–22.81%). Seropositivity among HCWs was lower than that of the general population (24.20%) which was estimated as part of the same study. Female HCWs had higher seropositivity 22.14% (95% CI 19.74–24.74%) as compared to 18.82% (95% CI 16.06–21.93%) among male HCWs and the difference was statistically not significant (Z = 1.66, P = 0.097). Age groups with increasing age show increasing trend in the seropositivity among HCWs. Conclusion: As on October 2020, with 20.84% seropositivity among HCWs in Ahmedabad, one in every five HCW already demonstrate IgG antibodies against severe acute respiratory syndrome– coronavirus-2. Further scientific studies on seropositivity and the factors affecting the seropositivity may be carried out to uncover more details of immune reaction after COVID-19 infection.