July 7, 2021

expert reaction to full report on the Liverpool COVID-SMART Community Testing pilot

The full report of the Liverpool COVID-SMART Community Testing pilot, which aimed to improve detection and bring down cases using lateral flow tests open to all people without ‘official’ symptoms, has been published.

This Roundup accompanied an SMC Briefing.

Comment updated 08/07/2021: Dr Angela Raffle, Consultant in Public Health and Honorary Senior Lecturer University of Bristol Medical School; Population Health Sciences, said:

“An honest headline from the full report about the November 2020 to April 2021 Liverpool testing pilot would be ‘Do not impose piecemeal testing initiatives each run by separate agencies, at short notice and without sufficient attention to logistics, test performance in real life settings, training, quality assurance, or honest and consistent public information.’

“The press release glosses over this message and instead highlights a possible ‘21% reduction in cases compared with other areas’ during the early days of the testing initiative. There were no predetermined control areas. The 21% figure is derived from sophisticated modelling using data from Liverpool and from multiple other areas. Inevitably these data are subject to numerous variables, and there is a great deal of ‘noise’ in the system. Caution is needed in assuming that a difference between Liverpool and elsewhere in the early days of testing was attributable to mass testing, whilst the Christmas surge was not related to testing, nor amenable to interruption through testing. The summary of the report and the press release do not adequately reflect this need for cautious interpretation.”

“The report also lacks any analysis of the resources that were needed for population-wide testing, and whether this represents best value compared with other potential uses. This is an important question that in a fair and democratic society should not be ignored.

“In conclusion, the staff in Liverpool deserve praise for the monumental task they faced in delivering the pilot, for the learning that has come from it, and for the care they have put into data analysis and production of this report. The logistical difficulties of implementing a major testing programme with only one week’s notice are considerable. Reliable conclusions about the impacts on infections from such a complex intervention are probably unattainable. The evidence in this report provides no justification for the Government’s multi-billion pound initiative of widespread self-testing with an inadequately evaluated lateral flow test used outside of the actual manufacturer’s recommendations.”

Dr Alexander Edwards, Associate Professor in Biomedical Technology, Reading School of Pharmacy, University of Reading, said:

“This report fills in more details of the Liverpool Testing Pilot, and some of the key messages are generally relevant to public health interventions- a local focus on local needs is essential. While every case picked up offers the chance for someone to isolate before they pass the virus on, we still don’t know the best way to use lateral flow rapid tests.

The relevance of this study to the future whole UK situation remains unclear because the release of restrictions means that cases are likely to rise, and the pressure on testing, tracing, and public health services will therefore be very high. Various measures intended to reduce viral spread may be removed in the near future (for example removal of isolation for certain groups, reduction in school control measures, reduction in use of face coverings), and so the relevance of testing becomes unclear, without knowing the target.

“We can’t find out the impact of testing on transmission rates in this particular location/time period because too many interventions and changes took place at the same time. Furthermore, reducing cases by 20% during a period of exponential growth may not be enough to significantly change the path of an outbreak. Likewise, the situation now is very different – following vaccine rollout and with another new variant- and the performance statistics for diagnostic tests changes depending on how many cases are present. Lots of the study findings around the practicalities and messaging remain very powerful and provide a great base to build.

“Whilst it’s great to see these findings published, we still need more evidence to understand how best to use lateral flow rapid tests in the community. They remain cheap and more accessible than lab tests, but remain limited in analytical performance. There doesn’t seem to be new data in this report on the analytical and clinical performance of lateral flow rapid antigen tests, that wasn’t already reported. We still need more peer-reviewed evidence in mainstream clinical journals.

“The claim that such tests are good at picking up ‘infectious’ individuals still remains controversial and not in line with mainstream diagnostic guidelines for viral infection. You can argue both ways: naturally the tests are better at picking up cases if there is a lot of virus present in a swab, which is great; however, people with low viral levels could either be at the start of an infection (or have a poorly performed swab) or recovering from past infection. Many studies show clearly that levels of virus recovered on a swab can vary greatly, even from the same individual. The variation between different individuals is also very high. These arguments, don’t help build public understanding and trust in the testing system.

“The conventional way to adopt novel diagnostic tests is to base the intervention on carefully controlled trials, but this is very difficult during a rapidly changing pandemic situation. More investment into evaluation of diagnostic tests will help.”

‘Liverpool Covid-SMART Community Testing Pilot’ is study by the University of Liverpool and Department for Health and Social Care which was published at 00:01 UK time Wednesday 7 July.

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

www.sciencemediacentre.org/tag/covid-19

Declared interests

Dr Alexander Edwards: “I am co-founder of a diagnostic technology company but not developing COVID-19 tests.”

None others received.