A modelling report, from the Imperial College London MRC Centre for Global Infectious Disease, reports on the possible development of COVID-19 outbreak in the UK.
This Roundup accompanied am SMC Briefing.
Prof Ian Hall, Professor of Molecular Medicine, University of Nottingham, said:
“This research is based on modelling different scenarios using the best data available at present. Because we don’t know the actual rate of infection in the community at large there are some assumptions made about the relative severity of the case mix, but the assumptions made are I think reasonable based on what data we do have. The group are of course internationally recognised for their excellence in research.
“The best data to use currently are from China, where the more extreme isolation strategy has resulted in the epidemic coming under control with very few new cases being reported. However, the one thing we really don’t know is whether or not, as these restrictions are relaxed, there will be another surge in cases, or whether (as was the case with SARS) this won’t happen. So paying close attention to what happens in China will help inform the length of time restrictions are needed in the UK. The report also describes how restrictions could potentially be intermittently relaxed depending on case rates.
“One major issue is that we don’t yet know the number of asymptomatic positive individuals in the general population – a large screening study would be needed to identify this. If this number turns out to be high, then the case fatality rates may be overestimated. If it is low, the reverse is true.
“There are a number of different scenarios modelled in the report which have informed the current government advice. The one step which will need further consideration is whether or not closing schools and universities would have much impact.”
Dr Stephen Griffin, Associate Professor at Leeds Institute of Medical Research (LIMR), University of Leeds, said:
“This excellent study incorporates new data from Italy and the UK alongside information from China to model the potential scenarios applicable to the spread and impact of SARS-CoV2 infections within the UK and USA. It applies these data to specific population (e.g. census) and geographical information, allowing the trajectory of the epidemic to be modelled for both countries. The study compares scenarios where no action is taken with a measured “mitigation” policy, or a more aggressive “suppression” approach. The difference between these strategies is that mitigation seeks to slow down the rate of incidence for the epidemic such that health infrastructure is better able to cope, whereas suppression actively reduces the levels and rates of infection. Logically, the first approach requires less impactful socio-economic strategies. Mathematically, mitigation reduces the base reproductive rate from current estimates of between two and three, but not below one, whilst suppression seeks to bring this down to less than one resulting in the epidemic eventually dying out.
“The study paints a sobering picture with marked differences to previous estimates, showing clearly that mitigation will not only be insufficient to prevent the NHS becoming overwhelmed, but also has little impact on the overall numbers of severe cases and deaths over time. However, active suppression is predicted to have an effective impact upon all three of these numbers. Suppression strategies involving different combinations of social distancing and case isolation strategies were assessed with the general trend showing that the more aggressive the strategy, the better the outcome. With respect to school and university closures, the authors assume that children are able to spread infection with equivalent efficiency to adults, although little data exists in this area. The study also assessed the impact of adaptive interventions based upon ICU bed occupancy, which were able to control, but not eliminate SARS-CoV2 over a protracted period.
“This is one of the key studies that has informed the implementation of more drastic measures announced yesterday by the chief medical and scientific officers. The prediction of the UK outbreak being approximately three weeks behind that in Italy means that the timeliness of these interventions might well be beneficial, although it will be at least two weeks before such outcomes will be known. However, the socio-economic and psychological costs of suppression is considerable, which is one reason for delaying school closures for example.
“It seems probable, based upon these data, that elements of mitigation and suppression strategies may have to remain in place until a vaccine becomes widely available, which could require up to 18 months. However, the potential availability of an effective antiviral drug could help to lessen the dependence upon these non-pharmaceutical interventions. Moreover, the accuracy of such models might be better-informed by the availability of more UK-specific data, which could be achieved by ramping up community testing for the virus on a large scale, as achieved in Korea, for example. This may also help the potential implementation of adaptive strategies over longer time periods and is in accordance with WHO policy. The UK has an excellent public health, NHS and research capacity, which could work in unison to achieve widespread testing, such as seen during the Ebola outbreak in Western Africa. Investment in such an approach as well as in further research seems prudent, given the huge costs already endured by global and UK markets.”
Dr Graham Taylor, Senior Lecturer in Tumour Immunology, University of Birmingham, says:
“It is reassuring that the government is basing decisions on the best available scientific evidence and that this evidence is in the public domain. The infection model is well reasoned and will continue improve over time as current uncertainties regarding virus transmission and the effects of different interventions (such as social distancing) become known. We now all need to do our part, following the guidance from government to reduce spreading the virus within our communities as much as we can.”
Dr Michael Head, Senior Research Fellow in Global Health, University of Southampton, said:
“The publication of this evidence that is clearly informing UK policy is important and useful. The Imperial modelling show various scenarios that could happen with and without ongoing revisions of the measures that will need to be put in place over the coming weeks and months. As Ferguson and colleagues themselves say, there are still huge uncertainties around any future estimates, reinforcing just how difficult decision-making is during a pandemic.
“It would still be useful to know the full set of evidence that is informing decision-making, both in the UK and across other countries. I’d really like to see a dashboard, a little like the visualisations of case numbers and deaths per country, that stores the reasoning behind each country’s government policy. This should cover not just the UK, but as many countries as possible. An open access evidence base is not as headline-grabbing as discussing mortality rates, but no less important.”
Dr Tim Colbourn, Associate Prof Global Health Epidemiology and Evaluation, UCL Institute for Global Health, said:
“Overall I think this is an excellent piece of work from some of the world’s best infectious disease modelers and presents the models and policy options clearly. The results are sobering though. Very tough times ahead as the policy option that reduces the most deaths involves school and university closures and social distancing measures over 18 months for two-thirds of the time or more (the suppression option) and this has never been tried anywhere ever – can it work? One clear message is the need to massively increase the number of ICU beds in the NHS from the current 5,000, which looks so frighteningly few in Figures 2 and 3 (it’s the red line near the bottom being overwhelmed by most scenario lines, except the suppression option).
“I would love to know how often the authors plan to update this as new data becomes available. It is obviously of the utmost importance now, though would also really like to see the other evidence informing SAGE and government policy right now too. I would really like to know how massive scale testing strategies of the population could be utilised to manage the next 18 months – if people can know whether they’ve had it or not they can get on with things if they’ve had it, and of course with such a strategy local hot spots can be suppressed as in South Korea.”
As published on the Imperial website at 5pm on Monday 16th March, https://www.imperial.ac.uk/mrc-global-infectious-disease-analysis/news–wuhan-coronavirus/
All our previous output on this subject can be seen at this weblink: www.sciencemediacentre.org/tag/covid-19