Innova LFT Anyone??19 Nov 2020 19:10
Guardian have a fantastic story on the shambles of mass testing and highlights the limitations of the Innova LFT.
https://www.theguardian.com/commentisfree/2020/nov/19/operation-moonshot-england-screening-covid-testing-liverpool
Sir Muir Grey, a screening expert writing in the BMJ – alongside Mike Gill, a former regional director of public health, England – has just delivered a devastating verdict on the effectiveness of the testing programme now being trialled in Liverpool, with mega-labs opening next year.
The Innova test, one of two in use in Liverpool, has not been evaluated in these conditions. Grey writes, “The test’s instructions for use state that it should not be used on asymptomatic people”, in other words, not for broad population screening. An evaluation by Porton Down and Oxford University suggests, “the test misses between one in two and one in four cases. The false positive rate of 0.6% means that at the current prevalence in Liverpool, for every person found truly positive, at least one other may be wrongly required to self-isolate.”
When infection is detected, “few currently adhere to self-isolation”, 20% being one estimate. Grey notes with his usual dry understatement that “this is an obvious area for improvement before we embark on an expensive screening programme”. What’s more, those on low incomes may be less likely to present for screening for fear of needing to self-isolate. That underlines, he writes, “the importance of reducing the rate of false positive results and providing appropriate support – financial, psychological and material – to people who must isolate.”
Grey reveals, astonishingly, that “there is no protocol for this pilot in the public domain, let alone systems specification or ethical approval”. Spending this monumental sum “on an unevaluated, under-designed national programme leading to a regressive, insufficiently supported intervention – in many cases of the wrong people – cannot be defended”. But perhaps, I ask him, in this crisis, there was no time? He says the National Screening Committee could have scrutinised it, setting the right objectives, “in a week or so”.
There are firm rules in screening. “You never get 100% participation” – but if done correctly, “80-90% is achievable”. Getting the last 5% can cost as much as reaching the first 90% – but, he points out, in this case the hardest to reach are the ones you most need.
Test, test, test
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