select search filters
briefings
roundups & rapid reactions
Fiona fox's blog
The MRC Centre for Global Infectious Disease Analysis at Imperial College London, has published a report on the role of testing in COVID-19 control.
Dr Joshua Moon, research fellow in sustainability research methods in the Science Policy Research Unit (SPRU) at the University of Sussex Business School, said:
“Overall, the robustness of these models are strong, and paints a picture of just how complex this outbreak is.
“The data demonstrate the wide ranges of uncertainty still inherent in our understanding of covid-19. For example, the report quotes asymptomatic transmission as between 20% and 50% which is a huge range with implications for the reduction of ‘lockdown’ and the likelihood of a second wave.
“The assumptions made are based on prior empirical data, and the models are accurate. However, the interpretation of these models is somewhat questionable.
“To take a quote from the press release for example: “Testing is essential for pandemic surveillance but its direct contribution to the prevention of transmission is likely to be limited to patients, HCWs and other high-risk groups.” This is based on section 4 of the report which reports no original modelling results but a brief summary of findings from Wuhan and other modelling studies. The report uses these to make the argument that community testing is not essential because symptom-based contact tracing would be sufficient and that a test-based contact tracing regime would require ~60,000 daily tests. This section, however, forgets the earlier statistic of 20-50% asymptomatic transmission, which would heavily reduce the efficacy of symptom-based contact tracing.
“The key questions to be asking are how these results will inform and relate to current government strategy. Matt Hancock made a claim for 100,000 daily tests by the end of April, we cannot allow this modelling to become a rationale for easing up on achieving that target.
“On top of this, while this report suggests that symptom-based contact tracing is sufficient, this is still based on a number of assumptions and the question of efficiency versus precaution needs to be explored here.
“If the modelling proves correct and huge increases to testing capacity are an inefficient allocation of resources, then we will have spent more money that we could have done something more effective with.
“If this modelling proves incorrect and a huge increase in testing capacity would give marked improvements in response and reductions in transmission, then if the government do not achieve their testing targets we could see more illness and deaths than otherwise. The question of efficiency versus precaution is the question of whether we pay for this crisis in cash or in lives.”
Dr Penny Ward, Visiting Professor in pharmaceutical medicine at Kings College London and the Chair of the Education and Standards Committee of the Faculty of Pharmaceutical Medicine, said:
“I found the modelling analysis disappointing. The authors have simply compared the contribution of possible testing strategies to prevention of spread in a hospital setting and have focused on the contribution of healthcare workers to hospital transmission. They have made a likely false presumption concerning relative infectiveness of a symptomatic as opposed to an asymptomatic individual – they presume that asymptomatic cases shed less virus, but what little data we have about viral load suggests that they shed as much as a symptomatic individual. The discussion on testing in the community appears to have ignored the evidence from countries which adopted a more widespread test trace and quarantine approach early on (Germany being the prime example). More importantly, they do not seem to have considered the question of how we might need to amend our present approach to a future approach aimed at testing not only for coronavirus but also influenza (which is treatable) in anticipation of a second/third/fourth wave occurring as we approach the cough cold and flu season. Altogether this paper is a great disappointment and a missed opportunity to consider an assessment unbiased by concerns re application of resources as opposed to understanding what might be needed and then considering if we are prepared to make it happen.”
Dr Rupert Beale, Group Leader, Cell Biology of Infection Laboratory, Francis Crick Institute, said:
“The Imperial team have made a valuable contribution to the case for rigorous healthcare worker screening. We should have imposed robust mechanisms for this already. The case for preventing transmission within hospitals and care homes is overwhelmingly strong.”
https://www.imperial.ac.uk/mrc-global-infectious-disease-analysis/covid-19/report-16-testing/
All our previous output on this subject can be seen at this weblink: www.sciencemediacentre.org/tag/covid-19
Declared interests
None received.