Comparison of commercial assays and laboratory developed tests for detection of SARS-CoV-2

The global COVID-19 pandemic has led to the rapid development of tests for detection of SARS-CoV-2. Studies are required to assess the relative performance of different assays. Here, we compared the performance of two commercial assays, the cobas (R) SARS-CoV-2 (Roche Diagnostics) and Xpert (R) Xpress SARS-CoV-2 (Cepheid (R)) tests, and a laboratory developed RT-PCR test adapted for use on the Hologic (R) Panther Fusion (R) (Hologic (R)) instrument as well as Bio-Rad and QIAGEN real-time PCR detection systems. Performance characteristics for each test were determined by testing clinical specimens and reference material. All assays detect the pan-Sarbecovirus E (envelope structural protein) gene plus a SARS-CoV-2-specific target. The limit of detection for the E gene target varied from similar to 2 copies/reaction to >30 copies/reaction. Due to assay-specific differences in sample processing and nucleic acid extraction, the overall analytical sensitivity ranged from 24 copies/mL specimen to 574 copies/mL specimen. Despite these differences, there was 100 % agreement between the commercial and laboratory developed tests. No false-negative or false-positive SARS-CoV-2 results were observed and there was no cross-reactivity with common respiratory viruses, including endemic coronaviruses.