---
title: Dangers of using Cq values to diagnose COVID-19 | LGC, Biosearch Technologies
description: "Meta description: This panel discussion investigates the reproducibility of quantification cycles (Cqs) and how setting diagnostic cutoffs altered the clinical sensitivity of COVID-19 testing."
---

# **A lesson from COVID-19 on the dangers of using Cq to quantify nucleic acids**

![660x400_Cq-webinar-2](https://info.biosearchtech.com/hs-fs/hubfs/660x400_Cq-webinar-2.png?width=660&name=660x400_Cq-webinar-2.png "660x400_Cq-webinar-2")

Video player - panelVideo - Click to play video

## Abstract

SARS-CoV-2 RNA quantities, measured by reverse transcription quantitative PCR (RT-qPCR), have been proposed to classify individuals at greater likelihood of spreading infection as well as performance targets for IVD development and approval. A recent study investigated the reproducibility of quantification cycles (Cqs) – also referred to as cycle threshold (Ct) or crossing point (Cp) – and how setting diagnostic cutoffs altered the clinical sensitivity of COVID-19 testing.

 

During this panel discussion, our expert panelists will discuss why the study recommends that Cq values not be used in this way and will leverage their lessons learned from the pandemic to improve SARS-CoV-2 measurements and promote reproducibility across labs worldwide. Topics will include measurement science (metrology) and units, the potential impact on diagnostic performance and the development of IVDs, how the measurement science assisted external quality assessment providers and how this work was able to support thresholding in a real clinical setting. The panelists will also discuss the potential clinical impact of their findings as well as explore how the performance of diagnostic tests may be linked to the stage of the pandemic. For instance, is it better to deploy analytically less sensitive tests as a screening tool when the pandemic is growing rather than when it is more stable or decreasing?

## Speakers

![480x500_jim-hugget.branded](https://info.biosearchtech.com/hs-fs/hubfs/480x500_jim-hugget.branded.png?width=480&height=500&name=480x500_jim-hugget.branded.png "480x500_jim-hugget.branded")

#### Professor Jim Huggett

Science Fellow  
UK National Measurement Laboratory, LGC

![480x500_kathryn-harris.branded](https://info.biosearchtech.com/hs-fs/hubfs/480x500_kathryn-harris.branded.png?width=480&height=500&name=480x500_kathryn-harris.branded.png "480x500_kathryn-harris.branded")

#### Kathryn Harris

Consultant Clinical Scientist  
Royal London Hospital, Barts Health NHS Trust

![480x500_heinz-zeichhart.branded](https://info.biosearchtech.com/hs-fs/hubfs/480x500_heinz-zeichhart.branded.png?width=480&height=500&name=480x500_heinz-zeichhart.branded.png "480x500_heinz-zeichhart.branded")

#### Professor Heinz Zeichhardt

Professor of Virology  
Charité – University Medicine Berlin

## Watch now

Fill out this simple form and   
get **immediate access:**