Clinical Evaluation and Utilization of Multiple Molecular in Vitro Diagnostic Assays for the Detection of SARS-CoV-2

Kendall Cradic, PhD; Marie Lockhart, PhD; Patrick Ozbolt, MLS(ASCP); Lisa Fatica, MT(ASCP); Lorie Landon, SM(ASCP); Michael Lieber, MS; David Yang, MT(ASCP); Juanita Swickard, MBA; Nicholas Wongchaowart, MD; Susan Fuhrman, MD; Stella Antonara, PhD, D(ABMM)


Am J Clin Pathol. 2020;154(2):201-207. 

In This Article


Clinical Performance of Three EUA SARS-CoV-2 (COVID-19) Molecular Assays

For evaluation of clinical performance 184 nasopharyngeal specimens in UVT were tested on all 3 assays and compared. DiaSorin Simplexa and Roche cobas molecular assays demonstrated a PPA of 100% (33/33), while Abbott ID NOW showed a PPA of 91% (30/33) compared to the consensus standard. NPA was 100% (151/151) among all three assays Table 1.

Comparison of Matched Nasopharyngeal Specimens in UVT With Dry Oropharyngeal and Nasal Swabs

Specimen type comparisons (nasopharyngeal in UVT, dry oropharyngeal, and dry nasal) from 182 patients tested by Abbott ID NOW produced 100% concordance for positive (12/12/12) and negative patients (170/170/170). As a comparator, each nasopharyngeal specimen was also tested on DiaSorin Simplexa. All 12 positive specimens were correctly identified by DiaSorin Simplexa; however, 1 additional positive specimen was identified. The discordant sample was misidentified as negative on all 3 specimen types when tested on the Abbott ID NOW instrument Table 2.

Relative Analytical Sensitivity of SARS-CoV-2 (COVID-19) in 10 Patient Samples

Ten positive nasopharyngeal specimens were serially diluted in UVT and all dilutions were tested by Abbott ID NOW, DiaSorin Simplexa, and Roche cobas assays Figure 1. For each series, results were normalized to the last positive dilution resulted on the Abbott ID NOW to account for different starting concentrations. Relative to Abbott ID NOW, half of the specimens detected SARS-CoV-2 at 10× lower concentrations by DiaSorin Simplexa, indicating approximately 10-fold lower LOD for this assay. The Roche cobas assay produced 5 of 10 positive reactions at 100× lower relative dilution, indicating at least 100-fold lower LOD than Abbott ID NOW.

Figure 1.

Relative limits of detection of Abbott ID NOW, DiaSorin Simplexa, and Roche cobas using 10 nasopharyngeal swab-positive patient samples collected in universal viral transport medium. A 10-fold dilution series was made for each patient sample and tested on all 3 instruments until a negative result was obtained. For each patient series, results were normalized to the lowest detected dilution of Abbott ID NOW (1×) and the last detectable reaction below that dilution is indicated for each instrument. Each dot represents the lowest detected dilution for each patient relative to Abbott ID NOW. All data used for this analysis can be found in the supplemental dataset (all supplemental material is available at American Journal of Clinical Pathology online).