Automated molecular testing of saliva for SARS-CoV-2 detection

Matic, Nancy; Lawson, Tanya; Ritchie, Gordon; Stefanovic, Aleksandra; Leung, Victor; Champagne, Sylvie; Romney, Marc G.; Lowe, Christopher F.

With surging global demand for SARS-CoV-2 testing capacity, laboratories seek automated, high-throughput molecular solutions, particularly for specimens not requiring specialized collection devices or viral transport media (VTM). Saliva specimens submitted from patients under investigation for COVID-19 from March-July 2020 were processed in the laboratory with sterile phosphate-buffered saline in a 1:2 dilution and tested using manual extraction and a commercial assay for detection of the SARS-CoV-2 E gene (LightMix®) in comparison to the Roche cobas® SARS-CoV-2 Test on the cobas® 6800 instrument. 34.4% (22/64) of saliva samples were positive for SARS-CoV-2. Positive and negative concordance between the LightMix® and cobas® assays were 100%. The overall invalid rate for saliva on the cobas® 6800 (1/128, 0.78%) was similar to the baseline invalid rate observed for nasopharyngeal swabs/VTM. Saliva is a feasible specimen type for SARS-CoV-2 testing on the cobas® 6800 platform, with potential to improve turnaround time and enhance testing capacity.