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Performance characteristics of COVID-19 tests: a comparative study from Dr. Ulrich Eigner

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 4 Nov 2021 || By Manoj Gandhi, M.D., Ph.D. Shares: Versions of this article Original article. Tags COVID-19, QPCR, Sars-cov-2, SGTF

With over 240 million cases and more than 4.9 million deaths reported worldwide since the beginning of the pandemic1, SARS-CoV-2 diagnostic testing remains critical for countries with high rates of COVID-19. Diagnostic testing relies primarily on real-time PCR assays, which directly detect the presence of viral RNA to identify ongoing infections.

“Diagnostic Testing now is based, as you all know, on Real Time PCR tests, antigen tests, or antibody tests. But the most important is RT PCR tests which is recommended by the WHO, as the more sensitive and specific method.”

 

In response to the COVID-19 pandemic, Thermo Fisher Scientific has worked rapidly to develop a multiplex real-time PCR diagnostic kit to enable clinical and public health laboratories to quickly diagnose COVID-19 caused by SARS-CoV-2 infection. In his webinar, Dr. Ulrich Eigner, Head of Studies in Infection Diagnostics at MVZ Labor Dr. Limbach Heidelberg, evaluates the clinical performance of the TaqPathTM COVID-19 CE-IVD RT-PCR Kit as compared to cobas® SARS-CoV-2 Assay for detection of SARS-CoV-2. In his succinct yet informative discussion, Dr. Eigner explains how the TaqPathTM COVID-19 CE-IVD RT-PCR Kit performs well in comparative studies, demonstrates high clinical sensitivity as well as clinical specificity, and can even be used as a  good proxy for the presence of del69_70 mutation and surveillance of the B.1.1.7 VOC.

Innovation, Competence, and Quality for More than 40 Years

Labor Dr. Limbach & Kollegen has been a provider of innovative laboratory diagnostics at the highest quality level for more than three decades.2 Founded in 1979, the Limbach Group has now formed an expansive network of over 30 laboratories in Germany with more than 300 medical doctors specialized in fields such as Laboratory Medicine, Microbiology, Infectious Disease and Epidemiology, Human Genetics, and Transfusion Medicine. The organization offers a comprehensive range of tests based on the most recent recommendations, guidelines, and specialists.

A man smiling and wearing glasses

The MVZ Labor Dr. Limbach is located in Heidelberg, Germany, and employs more than 600 specialists, including over 30 physicians, and a large number of natural science experts who work together to provide services such as laboratory medicine, infectiology, molecular diagnostics and hygiene, as well as transfusion medicine and human genetics.1 Having performed over a million SARS-CoV-2 PCR tests since the beginning of the pandemic, Limbach brings us an illustrative evaluation of the clinical performance of TaqPathTM COVID-19 CE-IVD RT-PCR Kit

A Comparative Study

To evaluate the clinical performance of TaqPathTM COVID-19 CE-IVD RT-PCR Kit as compared to the cobas® SARS-CoV-2 Assay, 175 SARS-CoV-2 positive and 275 SARS-CoV-2 negative upper respiratory tract samples were selected, randomized, and tested using the two test methods in parallel.

“…the TaqPath COVID-19 CE-IVD RT-PCR Kit shows good concordance with the Roche Cobas SAR-CoV-2 Assay, more than 95% positive agreement and more than 95% negative [agreement]…”

 

The MVZ Labor Dr. Limbach demonstrates that the TaqPathTM COVID-19 CE-IVD RT-PCR Kit, with a clinical sensitivity and specificity of 100%, is a powerful and highly accurate method for the detection of SARS-CoV-2.

SGTF Signals the Presence of B.1.1.7 Variant of Concern

RNA viruses demonstrate high mutation rates in response to selective pressures3, and SARS-CoV-2 is no exception.  Several genetic variants of SARS-CoV-2 have been emerging and circulating globally throughout the COVID-19 pandemic. The B.1.1.7 variant (known colloquially as the UK variant) has many lineage-defining mutations, one of which is a modification to the spike protein via a deletion of amino acid 69-70.

“The TaqPath COVID-19 test uses a multi-target design to compensate for emerging SARS-CoV-2 mutations.”

The TaqPathTM COVID-19 CE-IVD RT-PCR Kit is a multiplex RT-PCR assay targeting the ORF1a/b, S and N genes. As a result of this 3-gene target assay design, a sample containing the 69-70del mutation will result in the detection of the ORF1a/b and N genes, but not the S gene. In other words, the sample shows an “S gene drop out”, or “S-Gene Target Failure” (SGTF).

S-gene target failure (SGTF) diagram

In his webinar, Dr. Ulrich Eigner demonstrates that this S-Gene Target Failure (SGTF) can be used to signal the presence of the B.1.1.7 Variant of Concern (VOC).

Learn More

Watch Dr. Ulrich Eigner’s full webinar, “Performance Characteristics of COVID-19 Tests – a Comparative Study”, here.

To hear more of the latest on SARS-CoV-2 testing, mutation, detection and surveillance, explore these informative, must-see presentations from ECCMID 2021.

For more information about the TaqPathTM COVID-19 CE-IVD RT-PCR Kit performance and how to order it, click here.

References

1 WHO Coronavirus (COVID-19) Dashboard | WHO Coronavirus (COVID-19) Dashboard With Vaccination Data

2 MVZ Labor Dr. Limbach Heidelberg (labor-limbach.de)

3 Complexities of Viral Mutation Rates | Journal of Virology (asm.org)

 

*  For in vitro diagnostic use.