A narrative rocketed around social media earlier today: An Imperial College study said that COVID-19 could kill 500,000 Brits, but in recent testimony, Neil Ferguson, the head of the group behind the study, put the number below 20,000. Clearly the lying alarmist was walking back his ridiculous predictions!
Well, no. The paper actually offered simulations of numerous scenarios. The one resulting in 500,000 deaths was one where Great Britain just carried on life as before. Other scenarios, where the country locked down whenever it was necessary to stop the disease’s spread, put death totals below 20,000. (See the rightmost death columns of Tables 4 and 5.)
Since the paper came out, Great Britain has adopted a strategy of aggressively containing the virus and expanded its intensive-care capacity, so a prediction of a much lower death toll and less stress on ICUs hardly seems surprising.
Models like this will always turn out to be wrong in some way or other, because they rely on very strong assumptions about aspects of the disease we haven’t thoroughly studied yet. If nothing else, the original Imperial model will be obsolete soon, because it didn’t predict what could happen with extensive testing and contact tracing, which is likely the next step once the spread is contained and we have enough tests to go around. But it hasn’t been walked back just yet.
Update: Ferguson himself explains all this in a Twitter thread:
1/4 – I think it would be helpful if I cleared up some confusion that has emerged in recent days. Some have interpreted my evidence to a UK parliamentary committee as indicating we have substantially revised our assessments of the potential mortality impact of COVID-19.
— neil_ferguson (@neil_ferguson) March 26, 2020