Sample-to-Answer and Routine Real-Time RT-PCR: A Comparison of Different Platforms for SARS-CoV-2 Detection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spreading all over the world and has caused millions of deaths. Several sample-to-answer platforms, including Cepheid Xpert Xpress SARS-CoV-2 (Xpert Xpress), have received emergency use authorization for SARS-CoV-2 nucleic acid detection as a point of care test in the United States. However, their application niche is unclear when compared with real-time RT-PCR assays cleared by the National Medical Products Administration in China. In this study, the clinical performance, sensitivity, and workflow of Xpert Xpress and two real-time RT-PCR kits (BioGerm kit and Sansure kit) were evaluated by the specimens from 86 symptomatic patients. The positive percent agreement of Xpert Xpress was 100% compared with 96.15% for the BioGerm kit and 90% for the Sansure kit. The negative percent agreement was 100% for all three assays. The limit of detection is 100 copies/mL for Xpert Xpress and 500 copies/mL for the BioGerm kit and Sansure kit. By serially diluting live positive specimens, the Xpert Xpress had better detection capability. In the workflow and throughput analysis, the turnaround time was 51 minutes for Xpert Xpress, 150 minutes for the BioGerm kit, and 210 minutes for the Sansure kit. This study provides some indication for diagnosis methods selection.