Validation and verification of the Abbott RealTime SARS-CoV-2 assay analytical and clinical performance

BACKGROUND: High-throughput assays for the SARS-CoV-2 virus are critical to increasing test capacity and slowing the spread of COVID-19. Abbott Molecular developed and received emergency use authorization (EUA) to deploy the new RealTime SARS-CoV-2 assay, run on the automated m2000sp/rt system. OBJECTIVE: To evaluate analytical and clinical performance of the RealTime SARS-CoV-2 assay compared to the SARS-CoV-2 CDC-based laboratory developed test (LDT) in clinical use by the University of Washington Clinical Virology Laboratory (UW Virology). METHODS: RealTime SARS-CoV-2 assay limit of detection (LOD) was evaluated by testing two dilution panels of 60 replicates each. Cross-reactivity was evaluated by testing 24 clinical samples positive for various non‒SARS-CoV-2 respiratory viruses. Clinical performance was evaluated using 30 positive and 30 negative SARS-CoV-2 clinical samples previously tested using the UW Virology SARS-CoV-2 LDT. RESULTS: Exceeding the 100 copies/mL LOD reported in the RealTime SARS-CoV-2 assay EUA product insert, 19 of 20 replicates were detected at 50 copies/mL and 16 of 20 replicates were detected at 25 copies/mL. All clinical samples positive for 24 non‒SARS-CoV-2 respiratory viruses were SARS-CoV-2 negative on the RealTime SARS-CoV-2 assay. The assay had high sensitivity (93%) and specificity (100%) for detecting SARS-CoV-2 in clinical samples. Two positive samples that tested negative with the RealTime SARS-CoV-2 assay had cycle numbers of 35.94 or greater and required dilution prior to testing. One of these samples was also inconclusive on the SARS-CoV-2 LDT. CONCLUSION: The RealTime SARS-CoV-2 assay is acceptable for clinical use. With the high-throughput, fully automated m2000 system, this assay will accelerate the pace of SARS-CoV-2 testing.