The Prime Minister has announced a new whole city testing approach to launch in Liverpool from Friday.
Dr Flavio Toxvaerd, University Lecturer at the Faculty of Economics, University of Cambridge, who specialises in the economics of infectious diseases and economic epidemiology, said:
“There are many reasons for testing. Researchers do random testing to understand the disease for scientific and planning purposes, while medical practitioners use tests to diagnose individuals and find the best possible treatment (ruling in and ruling out diagnoses). However, some tests are mainly intended to enable targeted interventions such as isolation and to encourage behavioural change.
“The incentives to get tested are complicated and may vary from person to person. A civic-minded individual who is asymptomatic but tests positive for COVID-19 may choose to self-isolate. This would be a desirable outcome. But others may take a positive test result as a cue to be less cautious, as they are no longer at risk of infection. They thereby put others at risk and in such cases, testing may backfire.
“For some, not knowing their infection status may be preferable to testing positive as a positive test may bring forced self-isolation and loss of income. Unless the government puts in place the right incentives, plausible deniability may look attractive to some who suspect they are infected but who stand to lose a lot from self-isolation. So a sensible testing policy must go hand in hand with proper support and incentives for those who test positive.”
Dr Tom Wingfield, Senior Clinical Lecturer and Honorary Consultant Physician, Liverpool School of Tropical Medicine, said:
“As a hospital doctor living and working in Liverpool, the pilot of mass coronavirus testing in our city is an important step towards regaining control of Covid-19 transmission.
“Success of this pilot will depend on: good test availability; rapid turnaround times with accessible results; adherence to self-isolation and quarantine measures; and high levels of participation.
“Success will also not be possible unless there is trust in the testing system. That trust will only be achieved through engagement with our communities and clear information about the benefits of participation.
“However, it is important that this pilot does not deflect from the hard questions that need to be asked concerning the overwhelming situation that hospitals in Liverpool find themselves in. These questions include why contingency measures, such as mobilisation of additional staff and resources, were not activated earlier, before our hospitals reached capacity.
“We have a duty of care to people with Covid-19 or any other condition. We want to be able to continue to offer the high level of care our citizens deserve. To do so, we must review the failures we have witnessed in this second wave and ensure they do not reoccur in the event of future waves.”
Dr Luke Allen, GP Academic Clinical Fellow, University of Oxford, said:
“This is exactly the kind of mass-testing that should have been introduced months ago. If it can be implemented smoothly then we will have a much clearer picture of how the virus is spreading. This granular detail will enable public health teams to trace both symptomatic and asymptomatic carriers, as well as their close contacts, and stop the virus in its tracks. There are several big ‘ifs’ though: people need to show up for testing, testing should happen repeatedly in order to track changes over time, and – most importantly – the track and trace system needs to function effectively.”
Dr Alexander Edwards, Associate Professor in Biomedical Technology, Reading School of Pharmacy, University of Reading, said:
“As a pilot study, there are plenty of potential benefits if we can learn about real-world performance of mass-testing methodology. The underlying questions about accuracy, speed, and acceptability must be carefully measured alongside gaining technical and logistical experience. Pinning down test performance in the field is surprisingly challenging, a worthwhile research goal. Running large-scale testing without carefully measuring performance is as unhelpful as treating patients with medicines without properly controlled clinical trials, because both provide incomplete data that is hard to interpret.
“We do now have plenty of information about relative accuracy of different “am I infected” tests, including different samples (e.g. swab vs saliva) and ways to detect virus (viral antigen by lateral flow; viral RNA by PCR, LAMP or other methods). Most of our accuracy information comes from controlled lab studies, but tests often perform differently in real world use. Different products/technologies have pros and cons.
“Some caution is needed to qualify headlines that mass testing will somehow transform the situation we are now in. Any testing program can only be helpful in reducing health and economic impact of COVID-19 if it fits into a larger, coherent and effective strategy to slow transmission. Testing can only reduce infections if it prevents those testing positive from spreading the virus further. To achieve this, support for people to isolate- either those who test positive, or anyone they encountered who could go on to become infected- is essential. By many measures current symptomatic community testing (Pillar 2) with contact tracing does not seem to be able to reduce the number of infections; it’s hard to see how expanding testing can help alone, but hopefully we’ll learn from the pilot in Liverpool.
“Technology and testing is one of our most powerful tools, but technology is nothing without a joined-up and supportive public health strategy.”
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