Seasonal Components of Annual Life Expectancy Change across Area-Level Deprivation Groups in Belgium: The Role of Influenza Outbreaks and Heatwaves

Ilia Klimkin , University of Louvain

Seasonality in mortality is characterized by higher mortality during the cold season and lower mortality during the warm season. Previous research has shown that excess winter mortality strongly affects life expectancy trends in European countries. In Belgium, the mortality difference between winter and summer remains high. Therefore, understanding the seasonal components of annual mortality changes – both for the entire population and across socio-economic groups – is essential. Between 2000 and 2024, life expectancy at birth (e0) in Belgium rose from 77.8 to 82.4 years, though growth was uneven, with declines in 2012 and 2015. These downturns corresponded to elevated mortality at the beginning of the year, primarily among older adults, suggesting influenza epidemics as key drivers. Similarly, heatwaves contributed to summer mortality increases in 2018 and 2019. Despite these observations, the precise contribution of seasonal mortality to annual e0 changes remains undiscovered. This study introduces an approach to measure the contribution of seasonal mortality elevations to annual life expectancy change. Applying this method to Belgian data reveals that episodes of e0 decline were largely attributable to excess mortality during winter months. Preliminary results suggest that fluctuations in winter mortality among older adults are the main contributor to annual mortality fluctuations. The relationship between socio-economic deprivation and the magnitude of winter and summer mortality peaks and its impact on annual mortality estimates remains unclear. Vulnerable populations may be more affected by influenza and heatwaves, but the higher baseline mortality in these groups may mask the effect of these seasonal events.

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 Presented in Session 102. Flash Session Seasonal, Climate- and COVID-19-Related Mortality