Comparison of Six SARS-CoV-2 Molecular Methods and Correlation with the Cycle Threshold Distribution in Clinical Specimens.

BACKGROUND: The detection of SARS-CoV-2 in patient samples is of critical importance in the management of patients and monitoring transmission in the population. However, data on the analytical performance characteristics for detection of SARS-CoV-2 in clinical specimens between individual targets within the same platform, and among different analytical platforms are limited. METHODS: Here we evaluated the performance of six different sample-to-answer SARS-CoV-2 detection methods -Roche cobas 6800, Cepheid GeneXpert, Diasorin Simplexa, Luminex Aries EUA, Luminex Aries RUO, and bioMerieux BioFire in clinical specimens with a range of viral loads. RESULTS: The positive percent agreement (PPA) between the Roche cobas 6800 and GeneXpert was 100%, Diasorin 95%, Aries EUA 74%, Aries RUO 83%, and BioFire 97%. Notably, in samples with cycle threshold (Ct) values below 30 for the E gene on the Roche cobas 6800 platform, we found 100% positive percent agreement among all platforms. Given these results, we examined the distribution of over 10,000 Ct values of all positive specimens from individuals at our institution on the Roche cobas platform. Nearly 60% of specimens from asymptomatic individuals had a PCR Ct value >30 as measured using the cobas 6800 assay E gene. CONCLUSIONS: Our results demonstrate performance characteristics between different platforms by Ct value, and provide data regarding the distribution of viral RNA present in positive specimens.