How exceptional has mortality been during the pandemic?

CMI 2021 image of data

The Continuous Mortality Investigation (CMI) has been publishing frequent updates on mortality in the general population during the pandemic. This blog looks back over 2020 and 2021 to put that period in historical context.

The coronavirus pandemic has had a substantial impact on mortality. We have seen 586,000 deaths registered in England & Wales in 2021, which is higher than in any year since 1985, except for 2020 which saw 608,000 registered deaths.

Age-Standardised Mortality Rates

However, a simple count of deaths can be a misleading measure of mortality, as deaths reflect the size and age of the population, not just mortality rates. To address this, the CMI’s analysis of general population mortality focuses on Age-Standardised Mortality Rates (ASMRs). These are hypothetical mortality rates, assuming that the age and gender distribution of the population were the same in each year, and provide a fairer like-for-like comparison between years.

Mortality during the pandemic

To consider the impact of the pandemic on mortality, we use mortality rates in 2019, the last full year before the pandemic had an impact on mortality, as a benchmark. Mortality for England & Wales in 2020 was 13% higher than in 2019, and mortality in 2021 was 7% higher than in 2019.

However mortality relative to 2019, which we refer to as “excess mortality”, has varied during the course of the pandemic:

  • Mortality in 2020 was similar to 2019 in the first quarter, but was exceptionally high in the second quarter, with some weeks seeing over twice the mortality rate of 2019. Mortality then fell below 2019 levels during the third quarter, before rising towards the end of the year.
  • Mortality in 2021 was about 50% higher than in 2019 for the first five weeks of the year. Mortality then fell below 2019 levels during the second quarter but was above 2019 levels throughout the third and fourth quarters. Roughly half of the excess mortality for 2021 occurred in each half of the year.

There is a striking difference in how mortality rates in 2020 and 2021 compare at different ages – while mortality for ages 65+ has been 7% lower in 2021 than in 2020, mortality for under-65s was around 3% higher in 2021 than in 2020.

Longer-term comparison

While mortality can be volatile from year to year, we tend to see falls in mortality over time and it is rare to see mortality in a year being higher than the preceding five-year average. That happened in 2020 and 2021, but only twice in the preceding fifty years.

Taken together, the two-year 2020-21 period has had mortality over 5% higher than the 2015-19 average. It is unusual to see a two-year period with mortality so far above the preceding five-year average – we have to go back eighty years to 1940-41 to find such an extreme period on this measure.

It is particularly unusual for two consecutive years to both be above the preceding five-year average – the previous time this happened was to 1962-63. i.e. each two-year period from 1963-64 to 2019-20 has had at least one year with mortality below the preceding five-year average. We have to go back even further, over a century to 1917-18, to find two consecutive years which were both as far above the preceding five-year average as 2020 and 2021.

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