The UK passed another grim milestone yesterday: the official death toll exceeded Italy’s, making ours the highest in Europe.

But experts warn we should be extremely careful about assuming that these figures are directly comparable between countries – and it could be some time before we know whether the UK really has suffered more fatalities than other nations.

Here’s why.

More deaths or different metrics?

There are various ways of calculating the UK death toll, each with their own strengths and limitations, as FactCheck has reported throughout the crisis.

What they don’t tell us is whether the UK has actually seen more coronavirus deaths than other countries – or whether we’re just better at counting them.

We know, for example, that as recently as 20 April, Spanish authorities were only including people who had tested positive for coronavirus in the national death toll.

In the UK, our definition of what counts as a coronavirus death is much broader. The Office for National Statistics includes any fatality where doctors mention covid-19 on the death certificate, whether or not the person was tested for the virus.

Spanish regions including Catalonia and Madrid have started to publish their own stats to take account of probable coronavirus deaths. These figures suggest the overall death toll in Spain could be much higher than the national government has so far announced.

The Spanish government has defended its approach on the grounds that it is in line with World Health Organisation guidance, and says suspected deaths should be analysed at a later stage. Dr Fernando Simon, a senior health official in charge of Spain’s response to the pandemic, has acknowledged that the “real number of deaths is hard to know”.

Meanwhile in France, the official tally includes hospital deaths and those who died in care homes (whether they were tested for covid or not). But unlike the UK, the national figure does not include people who died at home. French commentators have described the lack of data on these deaths as a “timebomb”. The government plans to add them to the official stats in June.

Even figures for “excess mortality” – how many more people are dying now compared to the same point in previous years – are difficult. The French statistical authority, INSEE, warns that their estimates are “very provisional” and will be revised with each new update. These stats are compiled based on filings from local town halls across the country – some of which are still completed on paper.

Different populations

Responding to yesterday’s ONS figures, Sir David Spiegelhalter, Winton Professor of Risk at the University of Cambridge, pointed to several factors that make crude comparisons between official death tolls unhelpful.

We have to bear in mind the size of the population (for example, the UK is 10 per cent larger than Italy), the urban density, the ethnic mix, movement in and out of the country and the average age of citizens, he says.

Professor Spiegelhalter notes as an example that the median age in Italy is significantly higher than it is in Ireland – which is important when we consider the risks associated with advancing age and coronavirus.

Asked what the official death toll figures tell us about the success or failure of government policies between countries, Professor Spiegelhalter said: “Even if I tried to adjust for all of these, I’d feel cautious about making conclusions.”

He told reporters: “The whole league tabling thing is a complete waste of time”.

FactCheck verdict

It’s true that the UK’s official death toll from coronavirus is now the highest in Europe. But it’s hard to know for sure whether we’ve actually suffered more fatalities, or whether the UK is better at recording deaths associated with covid-19.

Even if countries did measure pandemic deaths in the same way as one another, the size of the population, the urban density, ethnic mix and average age of citizens are all significant factors that cloud the comparison.

Leading experts think it’s too soon to say whether the UK has been hit the hardest by coronavirus. It may be months or years before we have a final reckoning.