Clinical performance and sample freeze-thaw stability of the cobas®6800 SARS-CoV-2 assay for the detection of SARS-CoV-2 in oro-/nasopharyngeal swabs and lower respiratory specimens

Introduction: Studies describing the performance characteristics of the cobas (R) 6800 system for SARS-CoV-2 detection in deep respiratory specimens and freeze-thaw stability are limited. The current study compares the clinical performance of the automated SARS-CoV-2 assay on the cobas (R) 6800 system to a lab-developed assay (LDA) and the cobas impact of freeze-thawing combined with lysis buffer. Methods: Both retrospective and prospectively selected deep respiratory samples and oroand nasopharyngeal samples in either E-swab (R) or GLYwere tested using the SARS-CoV-2 assay on the cobas (R) 6800 System and compared to a lab developed assay. Additonally, SARS-CoV-2 RNA stability was assessed after one freeze-thaw cycle with or without lysis buffer. Results: In total, 221 (58.3 %) oroand nasopharyngeal swabs, 131 (34.6 %) deep respiratory specimens, and n = 25 (6.6 %) swabs of unknown origin were included to study clinical performance. Only 4 samples gave discrepant results, all being positive in the LDA and not the cobas (R) 6800 system. For stability testing, 66 samples without and 110 with lysis buffer were included. No clinically significant difference was found in test results after one freeze-thaw cycle and addition of lysis buffer. Conclusion: Based on our findings, the cobas (R) 6800 SARS-CoV-2 RNA assay yielded similar results as the LDA in oro-/nasopharyngeal swabs and deep respiratory specimens. Moreover, the cobas (R) 6800 SARS-CoV-2 RNA assay yielded similar results before and after a freeze-thaw cycle, with better preservation of low viral loads in lysis buffer.