What does ‘excess deaths’ mean – and can it give a clearer picture of the number of coronavirus fatalities?

The daily published number of infections and deaths as a result of coronavirus has become a depressingly familiar snapshot of the impact the pandemic is having globally. But trying to extrapolate the total global death toll is not as simple as it first seems. And trying to compare the number of COVID-19-related deaths by country can be misleading and confusing.

Each country has its own way of recording deaths – and its own time frame for doing so. Some governments only count deaths in hospitals, for example. And without widespread testing it’s not easy to keep a check on the number of confirmed cases. Added to this, there are also differences in how causes of death are recorded: coronavirus may be the trigger but death can result from a wide range of complications.

This also means that trying to draw conclusions about which countries have managed the outbreak best, and what strategies are working, is difficult.

The concept of ‘excess deaths’ is increasingly being used as a better and more consistent way of measuring the virus’ impact. In simple terms, this is the volume of deaths that occur over and above the expected normal for that country and time period, based on historic averages.

Comparing a country with its own past means that factors such as population demographics, disease incidence, poverty, inequality and the effectiveness of healthcare systems are less liable to skew the data. A measure of excess deaths also tends to smooth out any differences in the way deaths are counted. It allows us to see the full impact of COVID-19 on mortality, including deaths that were not directly attributable to the virus.

And it is clear to see that there has been a peak in death rates in the first half of 2020.

A bigger picture

For example, at the highest peak, Spain had 155% more deaths in a week than usual, and the UK had 109% more, according to UK charitable body The Health Foundation. As the chart above shows, as the number of infections around Europe declines, the wave of excess deaths in each country recedes. Germany, which introduced a contact tracing system early on, has had a notably small number of excess deaths.

EuroMOMO, a European network which monitors morality and excess deaths as a result of seasonal influenza and other public health risks, has pooled figures from several countries to give a bigger picture.

The data shows that from March 2020 onwards, there were substantial excess deaths, with the highest mortality among those aged 65 and over. There were also marked excess deaths in the 45-64 age bracket. And some countries – notably England and Spain – also saw excess deaths in the 15-44 age group. There was no excess mortality seen in children under 15.

EuroMOMO analysis shows that at the peak level of mortality in Europe, there was an excess of 35,800 deaths, the vast majority of which were of people over 65. In comparison, the highest excess mortality in any week during the previous four years was 16,165 during the severe 2016/17 influenza season.

Another way of looking at the data is to compare the ratio of excess deaths to usual deaths. This gives a picture of how much the relative risk of dying has changed over the pandemic time period.

Inconsistencies between countries

In many countries, the excess mortality rates exceed the reported COVID-19 death toll by some margin. This is influenced by when countries started reporting figures, the level of testing and how deaths are recorded.

In countries with less testing and treating capacity, it is likely that the divide between the official coronavirus death toll and the excess death rate will be greater. For example, analysis done by the Economist magazine suggests that Jakarta’s reported death toll may only be around 12% of the reality, based on data about burials. The New York Times, meanwhile, notes that in March to May, Ecuador has recorded about 10,500 more deaths than usual compared to the same period in the past three years – about three times the reported number of COVID-19 deaths.

Not all countries have the capacity to report sufficiently consistent and accurate data to calculate excess mortality. There is also no recognised single source of excess mortality data.

Although there remain inconsistencies in the way some countries report excess deaths, as more accurate and detailed figures emerge, it will become clearer what some of the causes of excess deaths are in different countries. For example, how many are actually coronavirus deaths, and how many can be linked to overloaded healthcare systems, or delays in seeking treatment for other diseases?

Until more detailed analysis can be done, excess deaths can provide countries with a blunt measure of how well their efforts to curb the virus are working.