Limited Evidence of Mortality Displacement After COVID-19

All-cause mortality trends shifted sharply during the COVID-19 years, interrupting long-standing declines in many high-income settings. Recent mortality data from 2024 suggest that some countries may be approaching prepandemic trends, but an apparent improvement can have different explanations. One possibility is mortality displacement, sometimes called the harvesting effect, where frail or high-risk individuals die earlier than they otherwise would have during a crisis, producing a temporary deficit in deaths afterwards. Another possibility is broader recovery dynamics shaped by vaccination, changing restrictions and socioeconomic conditions. A cross-national assessment using harmonised weekly mortality data from 34 countries between 2015 and 2024 examined whether postpandemic mortality declines reflect displacement or longer-term population trends.

Measuring Excess Mortality and Mortality Displacement

The analysis used national vital registration data compiled in the Human Mortality Database Short-Term Mortality Fluctuations dataset, covering weekly all-cause deaths from January 2015 through December 2024. Countries were included based on high-quality national reporting, and populations were stratified by sex and age group: 0–14 years, 15–64 years, 65–74 years, 75–84 years and 85 years or older. January 2015 to December 2019 served as the prepandemic baseline from which expected mortality was projected forward.

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Expected weekly deaths for 2020 to 2024 were estimated by extending prepandemic mortality patterns with statistical modelling that accounted for seasonal variation and long-term trends. Excess mortality was defined as observed deaths minus expected deaths, allowing both positive excess mortality during crisis periods and negative excess mortality when deaths fell below baseline expectations.

Mortality displacement was defined as a statistically significant mortality deficit in 2023 and 2024 or in 2024 alone, following a period of excess mortality during the pandemic years. Pandemic years were treated as 2020–2022, with an alternative specification including 2023, while postpandemic years included 2023–2024 or 2024 alone. The mortality displacement ratio was calculated as the cumulative postpandemic deficit divided by cumulative pandemic-period excess mortality, expressed as a percentage.

Limited Country-Level Evidence of Mortality Displacement

Across 34 countries from 2015 to 2024, the dataset included 352,182,284 deaths. Median 2020 population composition was 50.75% female and 19.64% aged 65 years or older. Countries were grouped into quintiles according to cumulative excess death rates per 100,000 population between 2020 and 2022.

Statistically significant mortality displacement at the country level was detected in only three countries: Greece, Latvia and Poland. Estimated mortality displacement ratios were 10% for Greece, 21% for Latvia and 21% for Poland, indicating that only a portion of pandemic-period excess mortality was followed by lower-than-expected mortality in subsequent years. These signals were concentrated in countries with high pandemic-period excess mortality.

Several countries with relatively low pandemic-period excess mortality showed large displacement ratios that were not statistically significant. Denmark had an estimated ratio of 180% and Luxembourg 2770%, interpreted as reflecting small early excess combined with later mortality deficits rather than substantial displacement in absolute terms. Luxembourg recorded a statistically significantly negative cumulative excess death rate from 2020 to 2024 of −100 per 100,000 population. New Zealand recorded −35 per 100,000 during the same period, while Denmark recorded −21 per 100,000 with a confidence interval spanning negative and positive values.

Recovery Trajectories Differ by Region and Age

Recovery patterns varied across countries when assessed using annual excess mortality rates in 2024. The United States returned to its prepandemic pattern of stable all-cause mortality, with an excess mortality rate of 3 per 100,000 and a confidence interval ranging from −2 to 7. In contrast, most European countries had not resumed their prepandemic trajectories by 2024. Excess mortality rates ranged from 11 per 100,000 in France to 115 per 100,000 in Lithuania, with continued elevation observed in Norway, Switzerland, the Netherlands, Belgium, Spain, the United Kingdom, Austria, Italy and Lithuania.

Age-specific patterns showed that cumulative excess mortality between 2020 and 2024 was substantially higher in older populations than in younger groups. Among children aged 0–14 years, 22 of 34 countries recorded negative or statistically insignificant cumulative excess mortality over the period. Reductions beyond age 14 were uncommon, with only six countries showing declines among older populations and two of those reductions not reaching statistical significance.

Evidence of mortality displacement also differed across age groups. No statistically significant displacement was observed among children aged 0–14 years. In the 15–64-year, 65–74-year and 75–84-year groups, displacement was detected in subsets of countries with effect magnitudes ranging from 7% to 68%, 8% to 62% and 9% to 42% respectively. The strongest concentration appeared among adults aged 85 years or older, where 10 of 13 countries showed significant displacement, with ratios ranging from 6% to 106%. Many of these findings were concentrated in countries with the highest pandemic-period mortality burden.

Across countries with high-quality mortality reporting, postpandemic mortality declines were rarely explained by mortality displacement at the national level. Significant displacement was identified only in Greece, Latvia and Poland and was most evident among adults aged 85 years or older. By 2024, recovery trajectories differed across regions, with the United States returning to prepandemic mortality patterns while many European countries continued to experience elevated excess mortality. These findings indicate that postpandemic mortality deficits generally represent limited demographic effects rather than broad compensation for earlier excess mortality.

Source: JAMA Network Open

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