Source: United Kingdom – Executive Government & Departments
Boots have announced the launch of a brand new in-store COVID-19 testing service, specifically offered for those without COVID-19 symptoms, as part of its continued efforts to support the NHS and local communities during the COVID-19 pandemic.
Dr Julian Tang, Honorary Associate Professor in Respiratory Sciences and Clinical Virologist, University of Leicester, said:
“The press release is slightly confusing in places. The test they cite, LumiraDx, have details on their website here – freely accessible to all: https://www.lumiradx.com/assets/pdfs/covid-19-antigen-test/sars-cov-2-ag-test-spec-sheet-us.pdf and https://www.lumiradx.com/assets/images/new/pdf/sars-cov-2-ag-test-strip-product-insert-eua.pdf
“If this is indeed the test mentioned in the press release, it is NOT a PCR test, rather an antigen (i.e. a viral protein – specifically the nucleocapsid protein) test, which is why it is so quick – 12 minutes is what the manufacturer also states.
“These types of rapid antigen tests have been used for years for other respiratory viruses like influenza and RSV – and are of variable sensitivity. They perform better on samples with high viral loads – such as those taken early in infection, and in children who usually shed more of those viruses for longer. Generally better results are obtained when such kits are assessed/tested by laboratory-trained personnel, as is usually the case when generating these product specifications.
“But the press release seems contradictory in places saying that it offers in-store same day test results – but later, a 48 hr result when the swabs are sent elsewhere for testing. Similarly it says that it can be used for pre-flight screening – but then later on, states that it is not currently approved for this, as pre-flight testing must be done using a PCR-based assay.
“Regardless, from the limited data shown in their test specification, the test seems reasonably sensitive and specific compared to a reference PCR test: https://www.lumiradx.com/assets/pdfs/covid-19-antigen-test/sars-cov-2-ag-test-spec-sheet-us.pdf, though no details of this reference PCR assay is given – and of course the operator of this test may limit its performance if performed in-store.
“The manufacturer has also performed an impressive list of cross-reactivity/interference testing to check for any causes of false positive/negative tests in the presence of other respiratory viruses/bacteria, drugs, and body fluids:
“So, just based on the data supplied in their LumiraDx manufacturer product specifications, its performance appears to be as good if not better than other similar rapid antigen tests for other respiratory viruses like influenza and RSV – at least on paper.
“However, some additional evaluations should really be performed in a real-life, in-store situation to confirm this level of performance. This is normal for any newly introduced laboratory diagnostic kit.
“So one way to do this is for an extra swab to be taken (with patient consent) at the same time as that taken for testing using the LumiraDx test, to be sent to a local laboratory with an approved in-house PCR-based COVID-19, for testing in parallel, to compare the performance of the LumiraDx against this other ‘PCR gold standard’.
“In this way, the performance of the LumiraDx can be assessed in a real-life, everyday situation.”
All our previous output on this subject can be seen at this weblink:
Dr Julian Tang: “As a professional clinical virologist, our diagnostic laboratory performs assay evaluations regularly, and I advise clinical teams and GPs on the performance characteristics of such assays, and how their results are interpreted to assist with patient management.”