Wild shifts in the global mortality distribution

Philip Schellekens  |  
Recent changes in the rich-country share in measured COVID mortality are a distraction from the bigger picture

Ever since the arrival of Omicron, the distribution of the daily mortality toll across rich and poor countries has undergone some wild shifts. But let this not fool you. Despite recent volatility, the mortality share of high-income countries remains dominated by those of lower-middle and upper-middle income countries when we adopt an excess death perspective. And in cumulative terms it is abundantly clear that most of the suffering has happened in the developing world. 


Daily changes

Starting off with the evolution in daily mortality, we describe two types of mortality data – officially reported COVID-19 mortality and estimated excess mortality – and characterize how the daily numbers of fatalities based on the two concepts are changing over time across the World Bank income classification. Note that the latter divides the world into high, upper-middle, lower-middle and low income countries (HIC, UMIC, LMIC and LIC), where the group of UMICs, LMICs and LICs commonly refer to the developing world. The excess death numbers are taken to be the mid-point values of the estimates derived from the excess death model of The Economist. 

The two charts below describe the evolution in daily mortality shares across World Bank income groups for each mortality concept. Focusing on the period after January 1, 2021, they show some very considerable shifts in the mortality distribution. Of course, it should be noted that mortality levels have also changed considerably over time, with recent data showing much lower levels than before in large part thanks to vaccination. 

To characterize the shifts in greater detail, let us focus on snapshots for the following three dates: January 8, 2021 (the earlier peak in the HIC share in COVID-19 mortality), July 20, 2021 (when a trough was reached in the same variable) and the current date. 

The chart below then shows how dramatic the shift in daily COVID-19 mortality has been. On January 8, 2021, high-income countries claimed 59% of global deaths on a daily basis. About six months later, the HIC share dropped to 8%. Then it started to climb again reaching a value of 80% as of the latest information by the WHO.  The mirror image from the perspective of the developing world has been a large shift into especially UMICs and LMICs during the first half of 2021, followed by an equivalent reversal. 

Using the same dates, the chart below looks at the distribution of excess mortality. This distribution shows a number of differences both in terms of levels and evolution. First, the overall excess death share of HICs is much lower: as of today, for example, we get 80% for reported COVID-19 deaths vs 18% for estimated excess deaths as. Second, LMICs account for much higher shares now, surpassing the share of UMICs. Third, the drop in the excess death share of HICs in the first half of 2021 is much smaller than the drop in its COVID-19 share. 

Cumulative changes

This section examines the cumulative mortality distribution across World Bank income groups. It does so again for reported COVID-19 mortality and estimated excess mortality. Note that the charts will zoom into the period after January 1, 2021, even though the cumulative numbers cumulate the mortality data since the beginning of the pandemic. 

The first pattern to note is that the cumulative share for HICs saw an initial bump in 2021 (consistent with the very high daily shares discussed earlier), followed by a gradual decline. This decline got reversed slowly with HICs close to UMIC levels. LMICs are about 1/2 the value of UMICa and LICs are close to 0. 

The cumulative distribution for excess deaths looks radically different. First of all in terms of levels. LMICs, not HICs, dominate the global rankings. UMICs are at about 3/4 the value of LMICs and HICs at about 1/2 the level of UMICs. LIC shares are much lower, but not as close to 0 as the reported statistics would have us believe. Also, note the huge bump in LMIC mortality around May 2021. That was India, which drove up the LMIC excess mortality numbers. 

Taking the most recent value for the cumulative shares, let us compare the mortality distribution under both mortality concepts. The blue bar in the chart below shows the distribution based on reported COVID-19 mortality, whereas the red one is based on the estimates of excess mortality. We compare across World Bank income groups and also add the developing world category.


HICs have at times dominated the global mortality distribution and this has translated into their cumulative mortality share still dominating that of other World Bank income groups. 

However, as this post has shown, an excess death perspective completely changes that conclusion. Not only have the fluctuations in HIC mortality shares been far more muted relative to those of other income groups – particularly LMICs – we also see that the HIC share is much lower in cumulative terms. 

This goes again to underscore the fact that the main locus of the pandemic has been the developing world and that the rankings across income groups totally change when we consider the broader impact on excess mortality.

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