Detection of asymptomatic SARS-CoV-2 infections among healthcare workers: results from a large-scale screening program based on rapid serological testing
Preprint
- 4 August 2020
- preprint
- research article
- Published by Cold Spring Harbor Laboratory
Abstract
Objective: To evaluate the performance of two available rapid immunological tests for identification of severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) antibodies and their subsequent application to a regional screening of health care workers (HCW) in Tuscany (Italy).Design: measures of accuracy and HCW serological surveillanceSetting: 6 major health facilities in Tuscany, Italy.Participants: 17,098 HCW of the Tuscany Region. Measures of accuracy were estimated to assess sensitivity in 176 hospitalized Covid-19 clinical subjects at least 14 days after a diagnostic PCR-positive assay result. Specificity was assessed in 295 sera biobanked in the pre-Covid-19 era in winter or summer 2013-14Main outcome measures: Sensitivity and specificity, and 95% confidence intervals, were measured using two serological tests, named T-1 and T-2. Positive and Negative predictive values were estimated at different levels of prevalence. HCW of the health centers were tested using the serological tests, with a follow-up nasopharyngeal PCR-test swab in positive tested cases.Results: Sensitivity was estimated as 99% (95%CI: 95%-100%) and 97% (95% CI: 90%-100%), whereas specificity was the 95% and 92%, for Test T-1 and T-2 respectively. In the historical samples IgM cross-reactions were detected in sera collected during the winter period, probably linked to other human coronaviruses. Out of the 17,098 tested, 3.1% have shown the presence of SARS-CoV-2 IgG antibodies, among them 6.8% were positive at PCR follow-up test on nasopharyngeal swabs.Conclusion: Based on the low prevalence estimate observed in this survey, the use of serological test as a stand-alone test is not justified to assess the individual immunity status. Serological tests showed good performance and might be useful in an integrated surveillance, for identification of infected subjects and their contacts as required by the policy of contact tracing, with the aim to reduce the risk of dissemination, especially in health service facilities.Keywords
This publication has 10 references indexed in Scilit:
- Suppression of a SARS-CoV-2 outbreak in the Italian municipality of Vo’Nature, 2020
- Antibody tests for identification of current and past infection with SARS-CoV-2Emergencias, 2020
- Antibody responses to SARS-CoV-2 in patients with COVID-19Nature Medicine, 2020
- The value of hospital personnel serological screening in an integrated COVID-19 infection prevention and control strategyInfection Control & Hospital Epidemiology, 2020
- Profile of Immunoglobulin G and IgM Antibodies Against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)Clinical Infectious Diseases, 2020
- COVID-19 Antibody Seroprevalence in Santa Clara County, CaliforniaPublished by Cold Spring Harbor Laboratory ,2020
- Viral Kinetics and Antibody Responses in Patients with COVID-19Published by Cold Spring Harbor Laboratory ,2020
- Nowcasting and forecasting the potential domestic and international spread of the 2019-nCoV outbreak originating in Wuhan, China: a modelling studyThe Lancet, 2020
- Temporal Profile and Determinants of Viral Shedding and of Viral Clearance Confirmation on Nasopharyngeal Swabs from SARS-CoV-2-Positive Subjects: A Population-Based Study in Reggio EmiliaSSRN Electronic Journal, 2020
- Molecular and serological investigation of 2019-nCoV infected patients: implication of multiple shedding routesEmerging Microbes & Infections, 2020