Tracking changes in SARS-CoV-2 transmission with a novel outpatient sentinel surveillance system in Chicago, USA

• Published in: Nature communications Vol. 13; no. 1; pp. 5547 - 10
• Main Authors: Richardson, Reese, Jorgensen, Emile, Arevalo, Philip, Holden, Tobias M., Gostic, Katelyn M., Pacilli, Massimo, Ghinai, Isaac, Lightner, Shannon, Cobey, Sarah, Gerardin, Jaline
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22.09.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 631/114/2415; 631/326/596/4130; 692/700/478/174; Chicago - epidemiology; Coronaviruses; COVID-19; COVID-19 - diagnosis; COVID-19 - epidemiology; Diagnostic systems; Diagnostic tests; Disease transmission; Health surveillance; Humanities and Social Sciences; Humans; Indicators; Lead time; multidisciplinary; Outpatients; Patient admissions; Public health; Retrospective Studies; SARS-CoV-2; Science; Science (multidisciplinary); Sentinel Surveillance; Severe acute respiratory syndrome coronavirus 2; Surveillance systems; Trends; United States - epidemiology; Chicago; United States; United States > US; Chicago Illinois
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-33317-6

Public health indicators typically used for COVID-19 surveillance can be biased or lag changing community transmission patterns. In this study, we investigate whether sentinel surveillance of recently symptomatic individuals receiving outpatient diagnostic testing for SARS-CoV-2 could accurately assess the instantaneous reproductive number R ( t ) and provide early warning of changes in transmission. We use data from community-based diagnostic testing sites in the United States city of Chicago. Patients tested at community-based diagnostic testing sites between September 2020 and June 2021, and reporting symptom onset within four days preceding their test, formed the sentinel population. R ( t ) calculated from sentinel cases agreed well with R ( t ) from other indicators. Retrospectively, trends in sentinel cases did not precede trends in COVID-19 hospital admissions by any identifiable lead time. In deployment, sentinel surveillance held an operational recency advantage of nine days over hospital admissions. The promising performance of opportunistic sentinel surveillance suggests that deliberately designed outpatient sentinel surveillance would provide robust early warning of increasing transmission. In this study, the authors develop a method for estimation of SARS-CoV-2 community transmission rates based on a sentinel population of people seeking outpatient testing with recent symptom onset. This method has fewer operational delays than methods based on hospital data, and may be subject to fewer biases.