Results of German external quality assessment schemes for SARS-CoV-2 antigen detection

Published

August 14, 2023

Author(s)

Laura Vierbaum, Nathalie Wojtalewicz, Peter Grunert, Anika Zimmerman, Annemarie Scholz, Sabine Goseberg, Patricia Kaiser, Ulf Duehring, Christian Drosten, Victor Max Corman, Daniela Niemeyer, Holger F. Rabenau, Martin Obermeier, Andreas Nitsche, Janine Michel, Jim Huggett, Denise O'Sullivan, Simon Cowen, Peter Vallone, Megan Cleveland, Samreen Falak, Andreas Kummrow, Ingo Schellenberg, Heinz Zeichhardt, Martin Kammel

Abstract

The COVID-19 pandemic illustrated the important role of diagnostic tests, including lateral flow tests (LFTs), in identifying patients and their contacts to slow the spread of infections. INSTAND performed external quality assessments (EQA) for SARS-CoV-2 antigen detection with lyophilized and chemically inactivated cell culture supernatant of SARS-CoV-2 infected Vero cells. A pre-study demonstrated the suitability of the material. Participants reported qualitative and/or quantitative antigen results using either LFTs or automated immunoassays for five EQA samples per survey. 711 data sets were reported for LFT detection in three surveys in 2021. This evaluation focused on the analytical sensitivity of different LFTs and automated immunoassays. The inter-laboratory results showed at least 94% correct results for non-variant of concern (VOC) SARS-CoV-2 antigen detection for viral loads of ≥ 4.75 × 106 copies/mL and SARS-CoV-2 negative samples. Up to 85% had success for a non-VOC viral load of 1.60 × 106 copies/mL. A viral load of 1.42 × 107 copies/mL of the Δ VOC was reported positive in > 96% of results. A high specificity was found with almost 100% negative SARS-CoV-2 antigen results for HCoV 229E and HCoV NL63 positive samples. Quantitative results correlated with increasing SARS-CoV-2 viral load but showed a broad scatter. This study shows promising SARS-CoV-2 antigen test performance of the participating laboratories, but further investigations with the now predominant Omicron VOC are needed. A total of 711 data sets were reported for LFT detection. Pre-analytical steps are not considered in this EQA because the participants were advised to pipette a sample volume which can be absorbed by a standard swap. Thus, this evaluation focuses just on the analytical test sensitivity. The inter-laboratory LFT results showed high success in non-VOC SARS-CoV-2 antigen detection for a viral load of 4.75x106 copies/mL or higher as well as for SARS-CoV-2 negative samples. Inconsistent results with success rate of 55 % to 66 % in non-VOC SARS-CoV-2 detection were found for a viral load of 1.6x106 copies/mL. A viral load of 1.42x107 copies/mL of the delta VOC was reported as positive in over 96 % of results. Moreover, a high specificity was found for human coronaviruses HCoV 229E and HCoV NL63 with almost 100 % negative results of SARS-COV-2 antigen detection. Quantitative results displayed a good correlation with rising SARS-CoV-2 concentration but showed a broad scatter. This study shows promising SARS-CoV-2 antigen test performance of the participating laboratories, but further investigations with focus on the now predominant omicron variants are needed.

Citation

Scientific Reports

Pub Type

Journals

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Keywords

virus, SARS-CoV-2, antigen

Citation

Vierbaum, L. , Wojtalewicz, N. , Grunert, P. , Zimmerman, A. , Scholz, A. , Goseberg, S. , Kaiser, P. , Duehring, U. , Drosten, C. , Corman, V. , Niemeyer, D. , Rabenau, H. , Obermeier, M. , Nitsche, A. , Michel, J. , Huggett, J. , O'Sullivan, D. , Cowen, S. , Vallone, P. , Cleveland, M. , Falak, S. , Kummrow, A. , Schellenberg, I. , Zeichhardt, H. and Kammel, M. (2023), Results of German external quality assessment schemes for SARS-CoV-2 antigen detection, Scientific Reports, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=935339 (Accessed April 28, 2024)