SARS-CoV-2 Variants Genotyping and Diagnostic Performance of a 2-Genes Detection Assay

Abstract

Background: The emergence of the COVID-19 pandemic resulted in the unprecedented expansion of molecular testing technologies. This study aimed at evaluating the performance of the FluoroType® SARS-CoV-2 plus assay for SARS-CoV-2 detection as well as describing the detection of SARS-CoV-2 variants using the FluoroType® SARS-CoV-2 varID Q kit.

Methods: The study utilized 679 archived nasopharyngeal samples. Analytical performance and the diagnostic performance of the FluoroType® SARS-CoV-2 plus assay were determined using 320 samples and reference material. Variants identification on the FluoroType® SARS-CoV-2 varID Q assay was performed on 359 samples. The study was approved by the Aga Khan University Hospital Institutional Review Board.

Results: The FluoroType® SARS-CoV-2 plus assay's limit of detection was verified as 1.2 copies/µL. The repeatability SD and %CV were 2.45 and 9.8% while reproducibility had an SD and %CV of 1.39 and 5.68%, respectively, for the RdRP gene. The positive and negative percent agreement were determined to be 99.4% (95% CI; 98.1%-100%) and 99.4% (95% CI; 98.2%-100%) respectively. In the variants identification, samples from the original wave had no mutations identified while 12.3%, 49%, and more than 90% of the samples during the Alpha, Delta, and Omicron waves, respectively, had detectable mutations.

Conclusions: The FluoroType® SARS-CoV-2 plus assay demonstrated analytical performance comparable to the reference method with a diagnostic sensitivity and specificity of >99%. The FluoroType® SARS-CoV-2 varID Q assay achieved rapid detection of circulating variants.