The UK government recently asked all secondary schools to provide on-site COVID-19 testing for pupils, and advised secondary, college and university students to continue twice weekly testing, in an attempt to try and reduce transmission of COVID-19. However, researchers from University of Manchester have suggested that lateral flow test performance may be below par, falling short of the minimum criteria set by the World Health Organisation (WHO) and by the UK’s Medicines and Healthcare products Regulatory Agency (MHRA), therefore casting doubt on the effectiveness of this policy.
For their study, published in BMJ Evidence-based Medicine, researchers from the Faculty of Biology, Medicine, and Health at the University of Manchester and the Institute for Quality and Efficiency in Health Care in Cologne, set out to assess the diagnostic accuracy of rapid point of care tests for the diagnosis of current SARS-CoV-2 infections in children under real-life conditions.
They highlighted that debate is ongoing with regards the potential benefits and harms of testing in education sites. In addition, the authors pointed out that sensitivity estimates of antigen tests in adult populations vary broadly, are substantially lower than manufacturers report, and that "performance in paediatric populations remained unknown".
To investigate the sensitivity and specificity of lateral flow tests in children the researchers performed a systematic review and meta-analysis of studies from research databases and pre-print servers between January 2020 and May 2021.
They identified for inclusion 12 peer-reviewed journal studies and five pre-print studies, with the data from these studies – which compared antigen tests against PCR tests - being pooled to measure diagnostic sensitivity and specificity.
The data covered a total of 6355 children, and eight antigen tests from six different brands. The collected data involved samples collected from the nose and throat in 11 of the test evaluations, and in the remainder, samples were collected only from the nose. All but one of the studies involved sample collection by trained staff, the one other being by supervised sample.
Real-life Antigen Performance Varies Broadly
Overall, the evaluated tests had a sensitivity (how well a test picks up people who have a disease/infection) of 64.2%, and a specificity (how well a test picks up those who don’t have a disease/infection) of 99.1%.
The researchers went on to analyse the data comparing those children who were symptomatic and asymptomatic. They found that based on 3413 symptomatic children in 13 studies the pooled diagnostic sensitivity was 71.8% and the pooled diagnostic specificity was 98.7%.
For asymptomatic children the pooled diagnostic sensitivity was 56.2% while the pooled diagnostic specificity was 98.6%, based on 2439 children in 10 studies.
The researchers commented the "performance of current antigen tests in paediatric populations under real-life conditions varies broadly". Adding: "These observed differences in test performance between children with and without symptoms show that sensitivity and specificity are not inherent test characteristics."
Minimum Test Performance Requirements Not Satisfied
In their study the researchers do acknowledge some limitations of their research, namely that their review was limited to eight tests, when there are currently over 500 lateral flow tests on the market, and that inadequate reporting precluded quality assessment of most of the studies.
In addition, none of the included studies assessed sample collection by self-testing or by untrained people. They added that their findings may not be applicable to future SARS-CoV-2 variants, or to vaccinated children.
The authors said: "Sensitivity estimates of antigen tests varied broadly among studies and were substantially lower than reported by manufacturers."
They continued by pointing out that no test included in their review "fully satisfied the minimum performance requirements as recommended by WHO or the Medicines and Healthcare products Regulatory Agency".
They cautioned that although lateral flow tests extend testing capacity, complement PCR testing, and offer short turnaround of test results, they do "come at the price of lower diagnostic accuracy", which in turn increases the risk of missing cases and "may affect the planned purpose of the broad implementation of testing programmes".
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