Serosurveillance of Health Care Workers in a COVID Hospital: Immune Response, and Its Longevity

Abstract

OBJECTIVE We aimed to study the seroprevalence of coronavirus disease 2019 (COVID-19) and sustainability of the immune response in health care workers (HCWs). A cross-sectional study was conducted between October 7 and November 30, 2020, in a multi-specialty hospital in Eastern India designated as COVID hospital during this pandemic. Study participants included 2,110 HCWs, including those who have recovered from COVID infection. METHOD HCWs were required to complete a questionnaire and give written consent to participate in the study. Their venous blood sample was collected for serum analysis of IgG antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by chemiluminescent immunoassay. RESULTS Positive IgG antibodies were seen in 924 participants with a point prevalence of 43.79%. Slightly higher reactivity was seen in males. History of COVID-19 infection was noted in 10.9%, with the highest antibody response in 81% cases. A maximum of 87.9% reactivity was seen in the first two months, and a significant fall was noted in the fourth month, with reactivity seen in only 50% of the study participants. CONCLUSION SARS-CoV-2 infection is associated with a variable immune response in the infected population. The declining trend of the antibodies correlates with short-lived protective immunity and the possibility of re-infection. Further studies are needed to explore the probable reasons for varied seroprevalence.