Utilization of rapid antigen assays for detection of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) in a low-incidence setting in emergency department triage: Does risk-stratification still matter?

Given the rapid turnaround of point-of-care testing, various studies have utilized RAD tests at the point of entry into the healthcare system.1–4 However, most of these studies have occurred during periods of heightened transmission, with detection rates of 5%–21%.1–4 RAD testing in clinical scenarios with lower incidence, such as asymptomatic individuals, may potentially result in low detection rates with high false-positive rates.5 False-positive RAD tests have resulted in SARS-CoV-2–negative patients being admitted to coronavirus disease 2019 (COVID-19) cohort wards, with subsequent nosocomial transmission.2 Conversely, given broad variations in potential infectivity among individuals with false-negative RAD tests,4 negative RAD tests need to be interpreted cautiously, especially in the context of significant contact history or clinical syndromes compatible with COVID-19. [...]40 patients tested positive for SARS-CoV-2 by RAD; among them, 29 tested positive by PCR, with a mean cycle-threshold value for SARS-CoV-2 E-gene of 18.9 (Fig. 1). [...]RAD testing for SARS-CoV-2 as part of an admission-triage strategy demonstrated high sensitivity and specificity, even in a low-incidence setting.