Clinical Evaluation of Three Sample-to-Answer Platforms for Detection of SARS-CoV-2
Wei Zhen, Elizabeth Smith, Ryhana Manji, Deborah Schron, Gregory J. Berry
Abstract
uthorization (EUA) by the Food and Drug Administration (FDA) to identify SARS-CoV-2 positive patients. Our objective was to evaluate three sample-to-answer molecular diagnostic platforms (Cepheid Xpert Xpress SARS-CoV-2 [Xpert Xpress], Abbott ID NOW COVID-19 [ID NOW], and GenMark ePlex SARS-CoV-2 Test [ePlex]) to determine analytical sensitivity, clinical performance, and workflow for the detection of SARS-CoV-2 in nasopharyngeal swabs from 108 symptomatic patients. We found that Xpert Xpress had the lowest limit of detection (100% detection at 100 copies/ml), followed by ePlex (100% detection at 1,000 copies/ml), and ID NOW (20,000 copies/ml). Xpert Xpress also had highest positive percent agreement (PPA) compared to our reference standard (98.3%) followed by ePlex (91.4%) and ID NOW (87.7%). All three assays showed 100% negative percent agreement (NPA). In the workflow analysis, ID NOW produced the lowest time to result per specimen (∼17 min) compared to Xpert Xpress (∼46 min) and ePlex (∼1.5 h), but what ID NOW gained in rapid results, it lost in analytical and clinical performance. ePlex had the longest time to results and showed a slight improvement in PPA over ID NOW. Information about the clinical and analytical performance of these assays, as well as workflow, will be critical in making informed and timely decisions on testing platforms.