Why were Denmark’s Covid models better than England’s?
From today, the Nordic nation has annulled all its Covid laws
The extent of the failure of British Covid scientists in the pre-Christmas Omicron panic is only now becoming clear. As brutally documented over at the Spectator, the models produced by both the London School of Hygiene and Tropical Medicine and Warwick University were wildly pessimistic compared to what actually happened. It was a failure that very nearly bounced the Government into further lockdown-style measures before Christmas.
What is additionally troubling is that other countries’ modelling groups seem to have been much more successful. I spoke to Dr Camilla Holten-Møller, the chair of the Expert Group for Mathematical Modelling at Denmark’s public health agency ‘Statens Serum Institut’. She led the team that produced the models in December that informed Danish policy, and her group’s updated advice in January led to today’s cancellation of all Danish Covid restrictions (even as case numbers continue to climb to all-time highs).
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Take a look at their model from December 17th, showing how Omicron would rapidly take over Delta, and forecasting the upper and lower expectations of numbers of new hospitalisations each day. The dots are broadly within the cone — in other words reality roughly matched their predictions:
Compare that to Warwick University’s forecast of new daily hospitalisations, if we continued with ‘Plan B’ restrictions and didn’t impose any further lockdowns. The red line is what actually happened:
I did some back of the envelope calculations, and if we had had the Danish scientists in charge here in England, it looks like the estimates would have been a lot more accurate. Of course you can’t simply transpose these figures (and Denmark has had a higher Omicron surge than the UK) but it is a useful high-level exercise. The population of Denmark is 5.8m, while the population of England is 56m — almost exactly ten times the size. If you multiply the Danish forecasts by ten, you get a lot closer to what happened in England than the numbers put forward by the SAGE committee to our Government:
Of course, the Government (only thanks to cabinet and backbench pressure, no thanks to Chris Whitty or Patrick Vallance) rejected the advice of SAGE to introduce more restrictions, which turned out to be the right call.
But what is the explanation for this huge difference with the Danish modellers?
One idea might be that the Danes paid better attention to the real-world data coming out of South Africa at the time that Omicron was intrinsically much milder than Delta. On 17th December Neil Ferguson’s group at Imperial produced a meta-study that concluded that there was “no evidence of Omicron having lower severity than Delta.” Even at the time this felt like a bizarre finding, and evidence now seems to suggest something closer to 10%-20% of the severity of Delta. So that was overly cautious, we now can say for sure, bad information.
However, both the UK modelling groups and the Danish group produced a range of scenarios with different severities, and both used the 50% mid-point as most likely. So that doesn’t explain the difference.
Dr Holton-Møller suggested two other variables that might explain it.
The first was the attention the Danish groups paid to behavioural changes that weren’t mandated. In other words, from their observations over the course of the pandemic, people moderate their behaviour at times of high case numbers even if they are not forced to by the Government.
The British scientists, even a year and a half after the pandemic began, seem unwilling to consider this crucial factor. The discussion paper for the Warwick model admits that, while unmandated behaviour change is “highly likely… such dynamic changes are beyond the current capacity of this model.”
The other variable that Dr Holten Møller suggests might account for the difference is what she calls “susceptible depletion” leading to “peak shaving”. This is also crucial: failure to properly consider this means that early exponential growth rates are incorrectly forecast to continue much longer than they do in reality:
Dr Holten-Møller was careful not to criticise academic colleagues from British universities, but offered her input into a future enquiry into what went right and wrong with this process. “The modelling community needs to get together and look into each other’s successes and failures,” she said.
She did observe that the Danish modellers are “detached from the political situation” — which might explain why all the political parties support Denmark’s bonfire of Covid regulations, a scenario that would be unrecognisable in the UK or the US.
If there is to be a shake-up of British scientific advice, and a search for superior talent in the near-future, Camilla Holten-Møller might be one name to keen in the frame…
Do *NOT* do an internet search for “the Danish model”, or “Swedish model” or “Scandinavian model”. The results were*not* as expected.
Depends on your internet history, I should think, Prashant.
Well I got a load of adverts for second hand Volvos. As I said, not what I expected at all.
(Walks off in a Kenny Everett bowler-hatted huff).
Reminds me of the time I was due for after work drinks at a (quite famous) London pub, that I realised I didn’t know where it was.
So I Googled it. The pub’s name: Dirty Dicks.
I still wake up screaming!
Oof. And I’m surprised you managed to get past the UnHerd automated censor with your post!
Did get one response to “Swedish Model” that was of note
from the Swiss Policy Research unit. It absolutely rubbishes lockdowns, masks, etc
I try to follow any covid data coming out of Sweden, but I had not come across that one, so thank you for the link. Absolutely fascinating and salutary.
I don’t think it’s so different from the UK situation. All parties in UK accepted lockdowns, with the only pushback coming from Tory rebels.
All governments have to decide action based on modelling scenarios and such devastating actions as lockdowns inevitably have political consequences.
Where governments throughout the world have failed is that they have thrust their advisors onto centre stage instead of owning their decisions. So modellers became attached to the politics, like it or not.
Then USA liberal elites deliberately cultivated the divisive potential of pandemic restrictions in order to defeat Trump. Narrowly, in case we need to be reminded. The arrival of COVID in an election year was a godsend to them, as the 2008 crash was to Obama.
From the other side it looks like the US Republicans and Trumpers cultivated the vote-winning potential of pandemic liberalisation (in the teeth of the available evidence). It takes two to make a division, you know.
Yeah Trump screwed it up – how could you lose to Biden?
No, it isn’t that different from the UK situation, but the modelling given most prominence in the media and eventually wisely ignored by the government was – that’s the whole point of the article.
Freddie, in your interview you failed to ask about the previous drop of all Covid regulations (from last October, if memory serves me right), only to be reintroduced shortly after. I know we don’t know what the future holds, but it has to be stressed that Denmark is not turning away from restrictions; indeed they are ready to deploy them again in full force at a drop of a hat.
Indeed. Which is why I tend to trust them when they say they are not needed now.
Really! The restrictions were NEVER needed as Sweden clearly showed. The restrictions didn’t even flatten the curve. The virus came and went in waves, and none of the mandates had any effect. You can see that quite easily in the US by comparing different neighbouring states with very similar demographics. Just compare North and South Dakota: the north had mandates and restrictions, the South had nothing, and the curves for daily cases and daily deaths per million are superimposable.
I’m not saying you’re wrong but I find it hard to believe. If there’s a virulent disease going round and you don’t want it to spread, even without models you’d think that the common sense thing to do would be to avoid contact with other people as far as possible. You’d have to be a brave person to say “Carry on as normal”. There are still plenty of people who like to point out that the UK has a very high number of deaths compared with other countries and that we should have locked down much sooner. Are you saying that we would have had the same number of deaths if we’d had no restrictions?
Government restrictions were an incredible step. Public health campaigns are about giving information to allow the public to respond appropriately (remember the AIDS adverts?) As the Danes quite rightly included in their modelling, people modify their behaviour during a public health crisis, dependent on the threat. There is no suggestion that the South Dakotans didn’t modify their behaviour too, but the comparison shows government sanctions made little difference. The lack of trust from governments towards citizens and, importantly and perhaps more scarily, citizens towards each other, led to many invited authoritarian, ultimately pointless, ultimately harmful, policies.
Thank you Mathew, so I think what you are saying is that there was no need for government restrictions because people would do the right thing anyway given good guidance and information.
As it happens I have a Swedish neighbour who has relatives in Sweden. When we discussed it she said “Well of course Swedes are very sensible people and will do the right thing.” Not sure it applies to everyone here though.
Looking at the SPI-M-O minutes for 15 December it is clear that they didn’t have much faith in the great British public following suggestions :
They had good reasons for being circumspect :
In early December 2020 while the UK was recovering from its September / October wave there was plenty of messaging about “think carefully about what you are going to do this Christmas” – very Swedish style.
Clearly, very few people took this on board because the NHS almost but didn’t quite fall over on January 11th 2021, even with all its surge capacity in place and a year’s worth of experience of dealing with the virus.
Remember, this virus can only transmit if people meet.
P.S. They also got the predicition regarding hospital admissions for January 2022 spot on (6 January, 2,286 patients were admitted to hospital with COVID-19)
There are three more aspects here: Trust of citizens towards government, a willingness to act for the common good, and clear, consistent messaging. The first two are high in Scandinavia and apparently low in the UK and (especially) the US , but they are hard to change. People will follow advice if they trust the source and they are willing to take individual trouble for a better collective result. But if the authorities are united in saying that people need to act and what they should do, that does make a difference. That is actually one function of mandated rules – by simply communicating clearly what is the right thing to do and that this is very serious they get the message across, even without enforcement. The UK government with its naked opportunism, open flouting of rules, what with eye tests and Christmas parties, and with a loud and influential ‘we should do nothing’ faction, never gave a consistent message, even with lockdown rules added in. You cannot guide people if people know that whatever you say will be U-turned away next week if that gives better headlines.
As for ‘people are responsible’ – in the mouth of Johan Strauss or some Tory it means ‘everybody should be free to do what they feel like without pressure from anyone else’. ‘I am all right, Jack – you just mind your own business’. And people are sure smart enough to hear that – and act on it if that is what they feel like.
“That is actually one function of mandated rules – by simply communicating clearly what is the right thing to do and that this is very serious they get the message across, even without enforcement.“
But the message gets overwhelmed by / lost in the debate about coercion.
In 1923 Sidney Webb promised the Labour Party conference that “from the rising curve of the Labour votes it might be computed…that the party would win a clear majority…some time around 1926”. Of course Labour have never won a majority, but apparently even a century later it is beyond the capability of modellers to recognise that exponential growth from a low base usually tails off as numbers grow.
“Of course Labour have never won a majority”.
However they did do rather well in 1945, 1964 & 1997 as I recall.
Although much to our detriment, it must be said.
Short of 50% of the vote on all occasions.
But a majority of seats in the HoC, which is all that really counts.
When was the last time any party won 50% of the vote?
Also it is beyond the capability of the general public to accept that modellers are not all simple-minded idiots, and might even understand something about modelling.
Soon after the early modelling done by Ferguson in the epidemic, I read an analysis of the model he’d done, and concluded, not that he was simple-minded, but that those who relied on his doubtful figures or wrote articles which failed to consider it critically might well be so, or negligent.
Despite obvious problems, they continue to treat him as credible.
They may well understand about modelling but they do have some problems with real-world data!
We don’t even need to pay Camilla Holten-Møller, just sack our lot, ask Camilla for her numbers and add a zero. Then we get the benefit of her whole team and no interference from our politicians.
I’m not a mathematician but I think it’s completely wrong to use the Danish model to try to model English data simply by multiplying by 10. I don’t think it works like that at all. These are very non-linear systems. Small changes in parameters and starting conditions can have big effects on the results.
Yeah that made me laugh.
I believe the point is that multiplying the Danish numbers by ten – which is suboptimal for the reasons you describe – still produced *better* results than the Imperial team who were supposed to be modelling for England. The article is an indictment of British modelling (quite rightly) not a serious suggestion to multiply Danish forecasts by ten and stop there.
I must defend Chris Whitty and Patrick Vallance. Chris Whitty in particular said that any measures taken would themselves have adverse consequences, in particular closing schools. It was the failure of the media to listen to nuance which did so much damage.
You can’t be nuanced with the media. That’s a big mistake.
But if the media are the source of our problems – not politicians, public servants – shouldn’t that be the focus of our angst? Other countries don’t have hysterical media like ours.
Remember it was the media that originally bounced our politicians into abandoning a herd immunity strategy with protected vulnerables – I fall into the latter group and was quite happy with that approach, to isolate until vaccines and herd immunity made their impact.
I’ve always thought we were having the wrong type of people doing the modelling.
University academics are not the people to ask. Go instead to experienced engineers who employ modelling in their job.
These people have a much better grasp of reality (and responsibility with consequences).
” Danish covid models”? Sounds like something one would read on a sign outside some grubby Soho address?
Aaah ! The Spectator cherry picking again – one scenario out of a total of 12 presented by the Warwick modellers.
Neither Warwick or LSTHM plumped for any particular scenario as being more or less likely – they didn’t have enough data at that time about vaccine escape or severity of Omicron in the UK population (median age in the UK 40.5 compared with 27.6 in SA) to put all their chips on any particular number.
LSHTM + Stellenbosch Uni. given the estimated relative transmissibility of Omicron at the time (mid December), modelled four immune escape and booster effectiveness scenarios.
Boris clearly put all his chips on the “Low immune escape, high booster efficacy” scenario. He had choices and he took a punt.
So the Danes behave the same, or dare I say, better than the Swedes. Good for them.
The Danes have done a lot of testing and looking at their case distribution during their pandemic there is a very curious skewed distribution – the majority of their cases have been in the 20 – 29 year cohort, by a country mile, so little or no disease burden on their health care system. This also implies that the young (doing all the transmitting) made very sure they didn’t mix with any crinklies or wrinklies at least until they were all vaccinated.
Thanks again. You have already provided more illumination in your posts than Freddie Sayers will in his entire career.
Confirmation of two suspicions: Anything said by the anti-lockdown brigade is totally unreliable. And Boris took the decisions (as is his job), and went all in on the most favourable scenario (as was entirely predictable). The blame, as always, falls on the people who elected him.
This website is becoming boring
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