Abstract
In SARS-CoV-2 diagnostics, cycle threshold (Ct) values from qRT-PCRs semi-quantitatively estimate a patient’s viral load. However, relevant analytical differences between qRT-PCR assays are often neglected. This study was designed (i) to identify such differences between five commonly used assays and (ii) to demonstrate a straightforward strategy to harmonize them. QRT-PCRs for SARS-CoV-2 were carried out in 85 oropharyngeal swab samples using three fully automated (Alinity m, cobas ® 6800 and GeneXpert) and two semi-automated (genesig ® and RIDA ® GENE) assays. Qualitative results (positive/negative) showed excellent comparability between the fully automated assays, but not between the Alinity m and semi-automated methods. Ct values significantly varied between all the methods, with the median values ranging from 22.76 (Alinity m) to 30.89 (RIDA ® GENE) and 31.50 (genesig ® ), indicating the lowest sensitivity for semi-automated methods. Passing-Bablok analysis further revealed systemic biases. Assay-specific viral load concentration calculations-based on generated individual standard curves-resulted in much better comparability between the assays. Applying these calculations, significant differences were no longer detectable. This study highlights relevant analytical differences between SARS-CoV-2 qRT-PCR assays, leading to divergent decisions about the mandatory isolation of infected individuals. Secondly, we propose a strategy to harmonize qRT-PCR assays to achieve better comparability. Our findings are of particular interest for laboratories utilizing different assays.
Keywords: COVID-19; SARS-CoV-2; cycle threshold value; quantitative reverse transcriptase-polymerase chain reaction; viral load.
【저자키워드】 COVID-19, SARS-CoV-2, Viral load., Cycle threshold value, quantitative reverse transcriptase-polymerase chain reaction, 【초록키워드】 qRT-PCR, diagnostics, Laboratory, sensitivity, Viral load, cycle threshold, oropharyngeal swab, Patient, Isolation, Qualitative, automated, Quantitative, Concentration, Analysis, comparability, significant difference, infected individuals, RIDA, qRT-PCR assay, FIVE, SARS-CoV-2 qRT-PCR, highlight, lowest, identify, carried, significantly, assays, detectable, Applying, mandatory, the median, 【제목키워드】 qRT-PCR, harmonization, assessment,