Source: FT by Jemima Kelly
Sir David Spiegelhalter, an influential British statistician, has revised down his estimates of the proportion of people dying from Covid-19 who would have died in the coming year anyway, suggesting that figure is probably somewhere between 5 and 15 per cent.
Until now, many people on both sides of the debate have agreed with this assessment (though they have disagreed on what the appropriate response should therefore be). Even Imperial’s Neil Ferguson himself, who has been dubbed “Professor Lockdown” by the tabloids, told us back in early April that: “from our crude analysis, it’s plausible that of the order of two-thirds of the people that have died so far might have died in this year anyhow” (a comment that was jumped on by many sceptics on Twitter).
Though he has not put a figure on this until now, Sir David had told us in a previous interview that he believed the two-thirds estimate was too high, but that the number would nevertheless be “significant”.
Speaking to FT Alphaville on Friday, Sir David said:
I used to think this figure would be quite big but I’ve reduced my estimate now. I’m not going to put a precise figure on it, but I definitely think the proportion of those who would have died over the next year anyway would be well below a quarter, maybe 5 to 15 percent, rather than ‘less than a quarter’.
Sir David, who is the Winton Professor of the Public Understanding of Risk in the Statistical Laboratory at the University of Cambridge, and was formerly president of the Royal Statistical Society, said his reduced estimate was partly based on research carried out by University College London and published in The Lancet, showing that even among the over-85s with at least three comorbidities, we would still only expect 1 in 4 to die in the next year without coronavirus:
Sir David has previously shown that Covid-19 mortality risk (ie, the risk you have of dying if you contract the virus) follows a very similar pattern as general background risk (ie, the risk you have of dying in the next year anyway), a pattern that is not seen in many other pandemics. And he has not changed his mind on this – he added a note to his work on May 2 to clarify that he was not trying to suggest Covid “does not add to one’s normal risk”, and that instead it roughly doubles your chances of death in the coming year, if you catch it.
On mortality displacement, or “harvesting” – ie, a short-term increase in the mortality rate that then causes a subsequent drop in deaths because some of the most vulnerable people will have died during the earlier spike, as commonly happens during heatwaves for example – Sir David said:
There will be some harvesting, so we might expect excess deaths to drop and even go below normal. But this is not going to create a massive dip in the total excess deaths for the year.
It’s also unclear to what extent any dip would be offset by secondary non-Covid deaths that might be the result of the prioritisation of coronavirus across policymaking, such as hospital avoidance, delayed diagnoses of life-threatening conditions like cancer, or suicides.
Sir David is listed as a member of the government’s Scientific Advisory Group for Emergencies (SAGE) on its website, but he says he’s actually not a member, and has only attended one meeting, via the internet. The website also lists Ferguson as a member, though he resigned earlier this month.
Real estimates of mortality following COVID-19 infection – The Lancet