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Lateral flow tests found wanting

Tue, March 1st 2022

Research by Imperial College London suggests that lateral flow tests miss a substantial number of COVID-19 infections, particularly for people without symptoms emphasising the need for rapid, sensitive, accurate and portable tests.

Lateral flow tests found wanting

The importance of rapid, sensitive, accurate and portable testing for COVID-19 is emphasised by recent research into the accuracy of the lateral flow tests by a group from Imperial College and Birmingham University. The research, published by The BMJ, found that the proportion of people with current COVID-19 infection missed by a commercially available lateral flow test (LFT) was “substantial enough to be of clinical importance”.

The study looked at the effectiveness of the LFT devices in three settings: - ⁠symptomatic testing at an NHS Test-and-Trace centre, - ⁠mass testing in Liverpool in residents without symptoms, and ⁠- asymptomatic screen testing in students at the University of Birmingham.

It found that the lateral flow devices would miss between 20 per cent and 81 per cent of positive cases in the different settings – 20 per cent at the Test-and-Trace centre, 29 per cent in the city-wide mass testing, and 81 per cent in the university screen testing.

"A negative LFT should be used in conjunction with other measures (such as good ventilation, face masks) in [high-risk] settings to reduce overall risk," says Dr Anika Singanayagam Clinical Lecturer, Department of Infectious Disease at Imperial College who worked on the study Professor Ajit Lalvani, from Imperial’s National Heart & Lung Institute. She warns that claims LFTs can identify the “vast majority” of infectious cases are likely to be overstated and risk providing false reassurance to the public. Dr Singanayagam said: “Lateral flow tests will miss a proportion of people who are infectious, particularly during the early stages of infection. This means that using them as a ‘green light’ test, for example to go and visit a vulnerable person, could be providing false reassurance."

Professor Pantelis Georgiou, CEO of ProtonDx says that the study emphasises the need for a fast and accurate test which can be provided by the company’s innovative diagnostic Dragonfly. The Dragonfly SARS-CoV-2 test panel has the potential to detect current and emerging variants with PCR equivalent accuracy in less than 30 minutes and at any required location. In addition, its use of molecular testing techniques means Dragonfly is capable of detecting low viral loads associated with an early stage in the disease cycle.