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expert reaction to UKHSA Technical Variant Briefing and use of lateral flow devices (LFDs)

A comment from Professor Sheila Bird on the UK Health Security Agency (UKHSA) technical briefing document looking at the use of lateral flow devices (LFDs).


Prof Sheila Bird, Formerly Programme Leader, MRC Biostatistics Unit, University of Cambridge, said:

“At least three antigen lateral flow devices (LFDs) have been made available to the UK publics for self-testing. First was INNOVA/DHSC1.  At least two other LFDs have been distributed to the public for self-testing. The more recently distributed kit-types (Orient-Gene2; FLOWflex) require swabbing of nostrils only so that regular self-testing may be more attractive. But an attractive test for asymptomatic self-use – were it to perform poorly in terms of its sensitivity – is not necessarily a win.

“I have not located any published evaluation, whether by dual testing or otherwise, of the sensitivity of FLOWFlex for asymptomatic testing of UK citizens.  The “Information for Users” insert in the FLOWflex pack provides data about FLOWflex’s sensitivity when used for testing persons with symptoms – a different context from asymptomatic self-testing; and advises that test-results in be discussed with your doctor.

“Today’s UKHSA’s Technical Briefing 32 is informative insofar as (page 14) real world performance monitoring data from LFDs in deployment for asymptomatic testing during the Omicron era are being analysed currently. And, as I reported earlier this week, real-world monitoring of FLOWflex’s sensitivity for asymptomatic testing is being assessed currently by a dual-testing evaluation against Polymerase Chain Reaction (PCR).

“Ideally, citizens who order a postal 7-pack of LFDs and are eligible to take part in dual-testing evaluations would be randomized to one of three LFD-types so that like-with-like comparison could be made between LFD-kit-types in their performance against PCR.

“Dr Harries’s reassurance about LFD-performances in the Omicron era is caveated on page 15 of today’s UKHSA’s Technical Report 32 as referring to their performance in the laboratory setting with real-world evidence to follow.”

  1. Liverpool Covid-SMART Community Testing Pilot Evaluation Report (initial report on 23 December 2020; follow-up on 17 June 2021). See,Community,Testing,Pilot,Interim,Evaluation.pdf and
  1. Young BC, Eyre DW, Kendrick S, White C, Smith S, Beveridge G, Nonnemacher T, Ichofo F, Hillier J, Diamond I, Rourke E, Dawe F, Day I, Davies L, Staite P, Lacey A, McCrae J, Jones F, Kelly J, Bankiewicz, Tunkel S, Ovens R, Chapman D, Marks P, Hicks N, Fowler T, Hopkins S, Yardley L, Peto TEA. Daily testing for contacts of individuals with SARS-CoV-2 infection and



All our previous output on this subject can be seen at this weblink:



Declared interests

Prof Sheila Bird: SMB is a member of the Royal Statistical Society’s Working Group on Diagnostic Tests, of RSS’s COVID-19 Taskforce and of UKHSA’s Testing Initiatives Evaluation Board. In 2003, SMB chaired RSS’s Working Party on Performance Monitoring in the Public Services. SMB is hugely grateful to her female-scientist-friend for timely email.

None others received.

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