You might have seen this tweet doing the rounds this week:
“Just checking it now and it’s true. Per capita, the UK is now predicted to have the worst COVID-19 death toll in the entire world.”
It’s been “liked” and shared thousands of times.
The claim is based on the tweeter’s own analysis of a study from the Institute for Health Metrics and Evaluation (IHME), based at the University of Washington in the US.
News outlets have also reported the findings, which suggest the UK death toll could be the worst in Europe.
The researchers’ mean estimate is that some 66,000 Brits could die of coronavirus before August, with the number of deaths peaking on 17 April. If true, that would work out at around one death for every 1,000 people in the UK.
But leading experts are highly sceptical of whether the methods the IHME researchers used are applicable here.
Professor Neil Ferguson of Imperial College, whose research is thought to have prompted a dramatic change of direction from the British government last month, says “this model does not match the current UK situation”.
He told the Guardian the IHME figures were at least twice as high as they should be for current bed usage and deaths in the NHS, and that “their healthcare demand model is wrong, at least for the UK”.
Professor Ferguson is not the only one to advise caution.
Dr Simon Gubbins, Head of the Transmission Biology Group at the Pirbright Institute, said the model used by IHME researchers “does not describe the spread of SARS-CoV-2 (the virus that causes COVID-19) nor does it explicitly model the effect of social distancing on spread”.
He says “the IHME and Imperial models were developed for different purposes. The IHME one is a statistical model that was developed to advise healthcare providers on the potential resources needed to deal with COVID-19, primarily in the USA.
“By contrast, the Imperial one is a complex transmission model that describes the spread of SARS-CoV-2 in the UK and was developed to assess the impact of different control measures, such as social distancing, on COVID-19 cases and deaths”, Dr Gubbins explains.
He adds that we should not treat the outputs of any particular model as “a prediction of what is going to happen”. Instead, they are “plausible scenarios, based on knowledge at the time they were generated” and a number of assumptions that “can be used to help inform decisions of policy makers.”
Professor Sir David Spiegelhalter, who is Chair of the Winton Centre for Risk and Evidence Communication at the University of Cambridge, says he is “very sceptical of these IHME projections”.
They are “based on assuming a rather simple mathematical model for the whole course of the epidemic”, he says. “I suspect they will change a lot as new data arrives – we shall see.”
The caution is echoed by Professor Sylvia Richardson from the University of Cambridge, who is President Elect of the Royal Statistical Society and co-chair of the Royal Statistical Society Task Force on Covid-19.
Professor Richardson warns that the methods used by the IHME researchers “are well known for being extremely sensitive, and are likely to change dramatically as new information comes in”.
She describes the IHME predictions for UK deaths and the date of the virus peak as “both extreme and too precise, especially allowing for the limitations in the daily reports.”
“Time will tell, but I feel these current claims should be treated with considerable scepticism.”
Defending their report, the IHME have said that the research is designed to be updated daily and that given the UK is still at an early stage of its outbreak, the predictions may be revised.
All the more reason, then, to treat these findings with the caution other experts urge.