Dozens of in vitro diagnostics (IVDs) have received emergency use authorization (EUA) from the U.S. Food and Drug Administration (FDA) for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but how well these assays perform using clinical specimens has hardly been studied. This study compared the positive percent agreement (PPA) of ID Now (Abbott, Chicago, IL, USA) and Simplexa (DiaSorin, Saluggia, Italy) using a modified CDC method as the reference standard (1). All three methods are used as part of standard of care testing within our hospital system. Ninety-six remnant clinical specimens from April 2020 that tested positive for SARS-CoV-2 using standard of care testing were selected based on convenience and retested using the three methods. Fourteen negative controls (universal transport medium [UTM]) were included to control for carryover contamination. Specimens included 11 supervised self-collected nasal swabs in 2 ml normal saline and 85 provider-collected nasopharyngeal swabs in 3 ml UTM. The online Medcalc tool (https://www.medcalc.org/calc/diagnostic_test.php) was used to determine the exact Clopper-Pearson 95% confidence intervals (95% CI). It is well documented that IVDs for SARS-CoV-2 can return false-negative results in individuals with coronavirus disease 2019 (COVID-19) (2), and our study did not attempt to determine the clinical sensitivity of these assays.
