Comparison between the analytical sensitivity and clinical performance of two cobas SARS-CoV-2 tests based on high-throughput and point-of-care systems

• Published in: Biomedicine (Taipei) 2022-01, Vol.12 (2), p.40-47
• Main Authors: Lin, Tsai-Hsiu, Bui, Ngoc-Niem, Chang, Yu-Chang, Hsu, Li-Yun, Su, Yang-Di, Chang, Chieh-Min, Hong, Wei-An, Le, Uyen Nguyen Phuong, Huang, Su-Hua, Lin, Cheng-Wen
• Format: Article
• Language: English
• Subjects: Original
• ISSN: 2211-8039; 2211-8020; 2211-8039
• DOI: 10.37796/2211-8039.1334

ObjectivesThis study examined analytical sensitivity, specificity, and the clinical performance in detecting SARS-CoV-2 of the Cobas SARS-CoV-2 Test based on the high-throughput Cobas 6800 system and the Cobas SARS-CoV-2 & Flu A/B Test based on the point-of-care cobas Liat system. MethodsThe commercial reagents containing SARS-CoV-2 RNA subgenomes were diluted for assessing the sensitivity of the RT-qPCR assay. 385 nasopharyngeal swab specimens taken from contacts of COVID-19 cases were tested for the SARS-CoV-2 detection with both Cobas SARS-CoV-2 Tests. ResultsIn analytical sensitivity assays, the Cobas SARS-CoV-2 & Flu A/B Test on the Liat system had a lower limit of detection (12.5-25 copies/mL) than the cobas SARS-CoV-2 Test on the cobas 6800 system (25-50 copies/mL). In clinical performance assays, the cobas SARS-CoV-2 Test demonstrated 89.36% (42 out of 47) PPA (positive percent agreement) and 98.82% (334 out of 338) NPA (negative percent agreement) compared to the results of the Cobas SARS-CoV-2 & Flu A/B test. Among five discordant specimens, four had the positive result of the cobas SARS-CoV-2 test, but the negative result of the cobas SARS-CoV-2 & Flu A/B Test. Moreover, these discordant specimens had the Ct values of greater than 33 for the cobas SARS-CoV-2 Test, implying a very small number of virions in the samples. Remarkably, four specimens with a presumptive positive result of the cobas SARS-CoV-2 test had been confirmed by the Cobas SARS-CoV-2 & Flu A/B Test. Next, the scatter plots of the Ct values showed a highly positive correlation between cobas SARS-CoV-2 & Flu A/B Test and the cobas SARS-CoV-2 Test (R-squared value = 0.954-0.962). ConclusionsBoth SARS-CoV2 tests of the cobas 6800 and Liat systems produce reliable high throughput and point-of-care assays respectively for the early virus detection and the personal care decision-making during COVID-19 pandemic.