Comparative study of four SARS-CoV-2 Nucleic Acid Amplification Test (NAAT) platforms demonstrates that ID NOW performance is impaired substantially by patient and specimen type()

Lephart, Paul R.; Bachman, Michael A.; LeBar, William; McClellan, Scott; Barron, Karen; Schroeder, Lee; Newton, Duane W.

The COVID-19 pandemic in the United States created a unique situation where multiple molecular SARS-CoV-2 diagnostic assays rapidly received Emergency Use Authorization by the FDA, were validated by laboratories and utilized clinically, all within a period of a few weeks. We compared the performance of four of these assays that were evaluated for use at our institution: Abbott RealTime m2000 SARS-CoV-2 Assay, DiaSorin Simplexa COVID-19 Direct, Cepheid Xpert Xpress SARS-CoV-2 and Abbott ID NOW COVID-19. Nasopharyngeal and nasal specimens were collected from 88 ED and hospital-admitted patients and tested by the four methods in parallel to compare performance. ID NOW performance stood out as significantly worse than the other three assays despite demonstrating comparable analytic sensitivity. Further study determined that the use of a nasal swab compared to a nylon flocked nasopharyngeal swab, as well as use in a population chronically vs. acutely positive for SARS-CoV-2, were substantial factors.