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Standardizing COVID-19 PCR Tests using reference materials


Histogram of fluorescence seperates positive and negative measurement resultsPCR tests were used already at the beginning of the covid-19 pandemic. SARS-CoV-2 is an RNA virus. However, PCR can only detect DNA. Therefore, RNA is first transcribed into DNA. Next the DNA is specifically amplified. A high viral concentration generates a strong signal. This allows to use a PCR test to detect or exclude an infection by SARS-CoV-2. The analytical sensitivity of PCR tests can vary between laboratories. This could lead to variable test results between laboratories. Two reference materials were developed under the leadership of INSTAND for standardizing theses PCR tests. INSTAND is a German EQA provider. The two samples have different viral concentration. In a collaborative study PTB has measured the concentration together with other national metrology institutes (UK: National Measurement Laboratory at LGC, LGC-NML; US: National Institute of Standards and Technology, NIST). The concentration was measured with digital PCR. The results are published in PLOS ONE. The reference materials were already used in external quality assurance of German medical laboratories. This secures comparability of PCR tests.
Laura Vierbaum, Nathalie Wojtalewicz, Hans-Peter Grunert, Vanessa Lindig, Ulf Dühring, Christian Drosten, Victor Corman, Daniela Niemeyer, Sandra Ciesek, Holger Rabenau, Annemarie Berger, Martin Obermeier, Andreas Nitsche, Janine Michel, Martin Mielke, Jim Huggett, Denise O’Sullivan, Simon Cowen, Peter M. Vallone, Megan H. Cleveland, Samreen Falak, Andreas Kummrow, Thomas Keller, Ingo Schellenberg, Heinz Zeichhardt and Martin Kammel
RNA reference materials with defined viral RNA loads of SARS-CoV-2 - A useful tool towards a better PCR assay harmonization
PLOS ONE 17(1) (2022); DOI: 10.1371/journal.pone.0262656