Comparison of Four Molecular In Vitro Diagnostic Assays for the Detection of SARS-CoV-2 in Nasopharyngeal Specimens

Wei Zhen; Ryhana Manji; Elizabeth Smith; Gregory J Berry

When it comes to the hands-on and turnaround time of the four assays in this study, the 281 throughput and workflow evaluation are clearly shown in Table 5 is 2 hours and 40 min, followed by 5 results every 5 minutes after loading 120 samples; the total assay run 292 time for 120 specimens is approximately 4 hours and 35 min. It is also important to note that the Hologic 293 platform has longer hands-on time, since the technologist has to load the primers, probes, and other 294 consumables and the fact that 120 clinical samples have to be manually transferred to Sample Lysis Buffer 295 tubes. These steps, especially the pipetting of the specimen into the lysis tube, can be somewhat labor 296 intensive and time consuming, bumping the overall turnaround time for 120 specimens closer to the 7 297 hour mark. It is important to emphasize that each platform has their advantages. For workflow, TAT, and 298 ease of use, the three sample-to-answer platforms (DiaSorin Molecular, Hologic, GenMark) out-299 performed the modified CDC assay, which is a manual assay requiring many steps, specialized personnel, 300 All rights reserved. No reuse allowed without permission. author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This study has several limitations that should be mentioned. First, this was a single center study 305 and the majority of the specimens were frozen after initial testing on the GenMark assay. While these 306 limitations are present, they have been minimized by the fact that GenMark assay (which was the least 307 sensitive platform in the analysis) actually had a potential competitive advantage, since it was the assay 308 initially performed on fresh specimens. Second, while the number of specimens included in the clinical 309 correlation was only 104, the patient samples spanned the entire range of clinical positives and reflected 310 our overall true positivity rate, which was between 50-60% during this time period of the COVID-19 311 outbreak. 312