Plans to widen roll out risk serious harm
No one questions the need for evidence based approaches to covid 19 treatments and vaccines. Why then is this principle ignored for testing? The UK government is widening the roll out of the Innova lateral flow test without supporting evidence, and we understand that this may soon extend to further home use. This may cause serious harm. We call on the government urgently to change course.
Mass testing may be helpful and necessary in certain circumstances if delivered to a high quality, but the Innova lateral flow test is not fit for this purpose. Studies have shown that in symptomless people it misses the SARS-CoV-2 virus in a substantial proportion. In the Liverpool pilot study, 60% (95% CI 48% to 71%) of infected symptomless people went undetected, including 33% (19% to 50%) of those with high viral loads who are at highest risk of infecting others. [1] Among students in Birmingham, only 3% (1% to 16%) of those who would have tested positive on PCR were detected. [2] The Government continues to claim that the test detects 77%—a figure from an unrealistic study using laboratory scientists and experienced nurses running tests on symptomatic people. [3,4] At a recent select committee hearing, the Secretary of State for Health appeared uninformed about the reduced accuracy in real life settings of the Innova tests in Public Health England studies and has denied that the Liverpool study showed the test performed poorly. [5,6]
The government’s Test, Trace, and Isolate (TTI) Modelling Group includes experts in modelling infectious spread, but with little expertise in evaluation of diagnostic tests or mass testing programmes. This matters because the government is now relying on mathematical models rather than real world evaluations. [7] The models are limited by assumptions about test performance and how test results affect human behaviour. A recently published TTI model of repeated testing ignored the possibility of harm from false negatives, and made assumptions that test errors occur at random, like an unlucky roll of a dice. [7] While repeated rolls of a dice will increase the chance of you finally getting the result you want, this is not how testing behaves. False negative results happen for a reason, such as the person having a lower viral load or difficulties in swabbing which tend to recur with subsequent tests, reducing the chances of a true positive result. Together these assumptions overestimate benefits and underestimate potential harms. This is no way to produce evidence to support a population wide national testing programme.
Low test accuracy would be less dangerous if people being tested and the public at large received accurate information about the risks and implications of a false negative result. Instead they are being misled. Results from government studies have been selectively reported and some have not been reported at all. [3,4] Letters to schools and parents have wrongly stated that the Innova tests were “as accurate in identifying a case as a PCR test.” [8]
Rapid testing of asymptomatic people could be useful if the test detected people who were asymptomatic and actively infectious, and if those people went on to self-isolate and if their contacts were traced. However, in practice, only a subset of people testing positive with the Innova test are actively infectious and only a subset self-isolate. NHS Test and Trace is supposed to automatically initiate advice to self-isolate and contact tracing, but is notified to do so only if infection is confirmed by PCR. Some localities have adopted the pragmatic course of acting solely on the positive lateral flow test result which means that notification will happen only if they also undertake a “work around” to alert NHS Test and Trace. [9]
The government has championed the use of negative tests to enable visiting relatives in care homes, returning to work or staying in school despite known exposure to an infectious case, safe travel home for Christmas, and participation in sporting events, weddings and funerals. [5,8,10,11] We know of at least one confirmed outbreak caused when a healthcare worker with symptoms continued to work due to false reassurance from a negative Innova test result. [12]
More than £1 billion have been spent on purchasing lateral flow tests, but this is a tiny fraction of the full cost of delivering the testing programme. [13] Staff in schools, universities, care homes, and local public health teams are struggling under immense pressure. The added burden of delivering mass testing may jeopardise education, care of residents, and the critically important covid-19 vaccination programme.
In the face of so much evidence of harm and so little evidence of benefit, why is the government pushing the rollout? It seems at least plausible that this is because hundreds of millions of Innova testing kits were purchased before it was known how they would perform in people without symptoms and when administered by less than expert hands. These tests are now sitting in warehouses around the country. The message has gone out that “they have to be used,” or “as long as testing detects otherwise unknown cases, the whole exercise will be worthwhile.” Perhaps rather than potentially fuelling the UK’s outbreak, the warehoused kits could be donated to a country without PCR testing capacity that could use them in line with manufacturer’s instructions. [14]
Given all of the above, we call on the government to at least to pause the rollout of rapid asymptomatic testing using the Innova test, including its use in care homes, schools, communities and self-testing by untrained people at home, until clearer messaging on the risks of negative results can be developed. We also ask for full documentation relating to Innova’s emergency MHRA approval on 23 December to be made available, and for publication of full reports for all studies and models of the Innova test commissioned by the Department of Health and Social Security. Information materials should be revised to make explicit the extremely poor sensitivity of the Innova test for community and self-use among those without symptoms; and the aims, outcomes and full costings of mass testing of keyworkers, schoolchildren, university students, and care home visitors should be reviewed. Finally, since testing makes no difference unless followed by appropriate action, the UK needs a national scheme to enable self-isolation of cases and contacts through support, including financial and accommodation for those in need.
Jon Deeks, Institute of Applied Health Research, University of Birmingham.
Angela Raffle, University of Bristol Population Health Sciences and UK National Screening Programmes.
Mike Gill, former Regional Director of Public Health, and former member of UK National Screening Committee.
Competing interests: Jon Deeks leads the Cochrane covid-19 test evaluation reviews and is a member of the Royal Statistical Society covid-19 task force steering group. Mike Gill has no conflicts of interest. AR delivers training and education for the UK National Screening Programmes.
References
[1] Liverpool Covid-19 Community Testing Pilot. Interim Evaluation Report. 23rd December. https://www.liverpool.ac.uk/media/livacuk/coronavirus/Liverpool,Community,Testing,Pilot,Interim,Evaluation.pdf
[2] Ferguson J, Dunn S, Best A, Mirza J, Percival B, Mayhew M, Megram O, Ashford F, White T, Moles-Garcia O, Crawford L, Plant T, Bosworth A, Kidd M, Richter A, Deeks J, McNally A. Validation testing to determine the effectiveness of lateral flow testing for asymptomatic SARS-CoV-2 detection in low prevalence settings. medRxiv 2020.12.01.20237784; doi: https://doi.org/10.1101/2020/12/01/20237784
[3] Department of Health and Social Care. Oxford University and PHE confirm high-sensitivity of lateral flow tests. Press release, 11 November 2020. https://www.gov.uk/government/news/oxford-university-and-phe-confirm-high-sensitivity-of-lateral-flow-tests.
[4] Preliminary report from the Joint PHE Porton Down & University of Oxford SARS-CoV-2 test development and validation cell: Rapid evaluation of lateral flow viral antigen detection devices (LFDs) for mass community testing. 8 Nov 2020. https://www.ox.ac.uk/news/2020-11-11-oxford-university-and-phe-confirm-lateral-flow-tests-show-high-specificity-and-are
[5] Science and Technology Committee (Commons), Health and Social Care Committee. Oral evidence: lessons learnt, HC 877:Q543. 24 Nov 2020. https://committees.parliament.uk/oralevidence/1277/html/
[6] Interview with Matt Hancock. Andrew Marr Show BBC1 10th January 2021. https://ift.tt/38usL2v
[7] Fearon E, Fyles M, TTI Modelling Group. On the use of LFA tests in contact tracing: preliminary findings. https://ift.tt/2LFS20G
[8] https://ift.tt/39rUShJ
[9] Presentations and discussion at Local Government Association and Association of Directors of Public Health Webinar on Mass Testing 10 December 2020
[10] Prime Minister’s statement on coronavirus (COVID-19) 9 September 2020 https://ift.tt/3bH2I7X
[11] Different world by summer, 3 December livestream Prime Ministers Questions https://ift.tt/33K7HSO
[12] Personal communication January 2021 relating to cases and outbreaks in England
[13] data extracted from Government Contracts Finder https://www.gov.uk/contracts-finder
[14] Innova Medical Group. SARS-CoV-2 antigen rapid qualitative test. Instructions for use. Version A/02 2020-07-01. https://cdn.website-editor.net/6f54caea7c6f4adfba8399428f3c0b0c/files/uploaded/Innova-SARS-Cov-2-Antigen-test-IFU.pdf
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