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Lateral Flow Tests Could Miss a Substantial Number of COVID-19 Infections

Research suggests that the Innova LFT should not be relied upon to exclude active COVID-19 infections

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Ian Black, MsComm, MSc

Ian is the editorial assistant for LabX, Today's Clinical Lab, and Lab Manager. Before joining the team he obtained a masters in science communication from Laurentian University and an MSc in biology from Brock University. He has published several peer-reviewed papers and has a strong passion for sharing science with the world.

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Published:Feb 28, 2022
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A recent publication in The BMJ indicates that the proportion of COVID-19 infections missed by the Innova lateral flow test (LFT) should be considered of clinical importance. Lateral flow tests are an important component of COVID-19 spread monitoring. LFTs are far from perfect, however, and there are few studies that examine the proportion of infectious individuals who go undetected by these tests.

Based on testing at three locations, professor Jonathan Deeks and colleagues used empirical data to predict the proportion of Innova LFTs that would produce a negative result, specifically in individuals with high risk of SARS-CoV-2 infectiousness. This was then compared with predictions made by mathematical models. The authors’ analysis predicted that the Innova LFT would miss detecting 20 percent of viral culture positive cases attending an NHS Test-and-Trace center, 29 percent without symptoms attending mass testing, and 81 percent attending university screen testing without symptoms. 

“Allowing for the uncertainties in the results from our analyses, the proportion of people with current infection missed by the Innova LFT is likely to be of public health importance,” write the authors, “particularly in settings with greater proportions of infectious people with lower viral loads; where the tests are often being applied.”

Although they also stressed that, due to the difficulty in evaluating the accuracy of these tests, there is potential for error in the paper’s estimates, the authors conclude that “until new generation LFTs are available that meet the regulatory performance requirements, negative test results from LFTs cannot be relied on to exclude current infection.” 

Read more: Molecular vs Antigen vs Antibody COVID-19 Tests