SARS-CoV-2 Antibody Seroprevalence and Stability in a Tertiary Care Hospital-Setting

Background: SARS-CoV-2 infectionhas caused 64,469 deaths in India, with 7, 81, 975 active cases till 30th August 2020, lifting it to 3rd rank globally. To estimate the burden of the disease with time it is important to undertake a longitudinal seroprevalence study which will also help to understand the stability of anti SARS-CoV-2 antibodies. Various studies have been conducted worldwide to assess the antibody stability. However, there is very limited data available from India. Healthcare workers (HCW) are the frontline workforce and more exposed to the COVID-19 infection (SARS-CoV-2) compared to the community. This study was conceptualized with an aim to estimate the seroprevalence in hospital and general population and determine the stability of anti SARS-CoV-2 antibodies in HCW. Methods: Staff of a tertiary care hospital in Delhi and individuals visiting that hospital were recruited between April to August 2020. Venous blood sample, demographic, clinical, COVID-19 symptoms, and RT-PCR data was collected from all participants. Serological testing was performed using the electro-chemiluminescence based assay developed by Roche Diagnostics, in CobasElecsys 411. Seropositive participants were followed- up to 83 days to check for the presence of antibodies. Results: A total of 780 participants were included in this study, which comprised 448 HCW and 332 individuals from the general population. Among the HCW, seroprevalence rates increased from 2.3% in April to 50.6% in July. The cumulative prevalence was 16.5% in HCW and 23.5% (78/332) in the general population with a large number of asymptomatic individuals. Out of 74 seropositive HCWs, 51 were followed-up for the duration of this study. We observed that in all seropositive cases the antibodies were sustained even up to 83 days. Conclusion: The cumulative prevalence of seropositivity was lower in HCWs than the general population. There were a large number of asymptomatic cases and the antibodies developed persisted through the duration of the study. More such longitudinal serology studies are needed to better understand the antibody response kinetics. Funding Statement: CSIR Project MLP 2003 (Combined Digital Surveillance and Effective COVID-19 Testing Frameworks and Tools) provided funding this work. SN acknowledges CSIR for fellowship. RP acknowledges the funding from Fondation Botnar (CLP-0031) and CSIR (MLP-2005) towards the study. Declaration of Interests: The authors have declared no competing interest. Ethics Approval Statement: Ethics approval was taken from the Institutional Ethics Committee of Max Super Speciality Hospital, Saket, New Delhi (REF NO.:RS/MSSH/DDF/SKT-2/IEC/ENDO/20-12). Employees of Max hospital were approached by an email for participation in this study. Individuals from the general population visiting the hospital for COVID-19 testing were also recruited in the study. Written informed consent was obtained from all participants.