Sustained excess all-cause mortality post COVID-19 in 21 countries: an ecological investigation

Abstract

Background: Despite widespread vaccination efforts, significant excess mortality continued in various countries following the COVID-19 pandemic. This study aims to estimate excess mortality during 2022 in 21 countries and regions, and to examine the relationship of governmental control measures and vaccination rates with excess mortality during 2021-2 at an ecological level.

Methods: Excess mortality for 2022 was estimated by analysing weekly mortality data from January 2020 to December 2022 across 21 countries and regions participating in the C-MOR consortium. This was achieved by comparing the observed age-standardized mortality rates per 100 000 population to a baseline derived from historical data (2015-19). Governmental control measures and vaccination efforts were investigated for their association with weekly excess mortality during 2021-2 in multilevel models with country as a random effect.

Results: All 21 countries experienced excess mortality in 2022, ranging from 8.6 (Peru) to 116.2 (Georgia) per 100 000 population, noting that rates were not directly comparable across countries. Many countries had higher excess mortality in 2022 compared with previous years. Mauritius showed a significant excess mortality for the first time in 2022. The proportion of COVID-19 deaths relative to total deaths decreased in 2022 for most countries, except Australia. Governmental control measures and vaccinations were associated with reduced excess mortality in 2021 and 2022, respectively.

Conclusion: The study reveals sustained excess mortality throughout 2022. Excess deaths were mainly non-COVID-19-related, likely due to displaced mortality or to broader long-term impacts of the pandemic response. Governmental control policies and vaccination efforts were associated with lower excess mortality. These findings provide critical insights into pandemic mortality dynamics and emphasize the need for continued vigilance and adaptive public health strategies.

Keywords: COVID-19; all-cause mortality; excess mortality; governmental control measures; indirect mortality; vaccination.

Figure 1.

Cumulative excess age-standardized mortality rate for total population for 2020, 2021, and 2022. Plot letters correspond to the age groups in which countries have provided data and therefore the age groups used for age standardization: (A) age groups <15, 15–44, 45–64, 65+years; (B) age groups <20, 20–49, 50–69, 70+ years; (C) age groups <45, 45–64, 65+years; (D) age groups <15, 15–64, 65+years. The magnitude of excess mortality is not directly comparable between countries reporting mortality data in different age groups.

Figure 2.

Male-to-female cumulative excess age-standardized mortality rate ratios for 2021 and 2022. The 2021 rate ratio for Belgium is 13.4, which is beyond the x-axis limit and therefore is not depicted. Values of >1 denote a higher excess mortality in males compared with females.

Figure 3.

Country-specific overall CMRs for 2020–2, separated as other causes of death vs COVID-19 deaths. The lighter-colored portion of each bar illustrates COVID-19 deaths. Vertical lines show country-specific baseline (expected) mortality calculated as the average of crude all-cause death rates between years 2015 and 2019.

Figure 4.

Multilevel model results on the relationship between individual governmental control policies (3-week lag) and excess mortality z-score in (A) 2021 and (B) 2022. Multilevel models included country as a random effect and categorical governmental control measures as fixed effects, adjusting for total vaccinations and non-COVID-19 mortality. A separate model was built for each governmental control measure. Each point represents the regressioncoefficient for each control measure level and whiskers represent the 95% CIs. Lack of regression coefficients for particular control measure levels indicates that that level was not implemented in the respective year analysed.