Lack of sensitivity of an IVD/CE-labeled kit targeting the S gene for detection of SARS-CoV-2

Matzkies, Lucie-Marie; Leitner, Eva; Stelzl, Evelyn; Assig, Karoline; Bozic, Michael; Siebenhofer, David; Mustafa, Maria E.; Steinmetz, Ivo; Kessler, Harald H.

OBJECTIVES: New molecular tests for SARS-CoV-2 are rapidly launched in response to the COVID-19 pandemic. The aim of this study was to evaluate the analytical and the clinical performance of the VIASURE SARS-CoV-2 S gene RT-PCR Kit on the BD Max™ system and to compare results with those obtained with the cobas® SARS-CoV-2 test on the cobas® 6800 system. METHODS: For testing the analytical performance, reference material was used. Clinical samples (n=101) obtained from patients with symptoms compatible to COVID-19 were studied. Oro- and nasopharyngeal swabs were collected by using either ESwab™ or UTM™ collection systems. RESULTS: When the analytical performance was evaluated, the sample containing the lowest SARS-CoV-2 concentration tested negative with the VIASURE test while results obtained with the cobas® test were found to be concordant with the results expected. Six out of the 101 clinical samples (5.9%) showed an inhibition with the VIASURE test. When analyzing the remaining 95 clinical samples, 27 were found to be negative with both assays. Of 68 samples positive with the cobas® test, the VIASURE test missed 21 (30.9 %) samples. All of those 21 samples had shown Ct values ≥ 31 with the cobas® 6800 system. None of the samples tested positive with the VIASURE test and negative with the cobas® test. CONCLUSIONS: The VIASURE test was impaired by a lack of sensitivity and a relatively high number of invalid results. When using the VIASURE test for routine testing, a significant number of COVID-19 positive samples would have been missed.