Excess Mortality as the Primary Mediator of COVID-19’s Impact on Life Expectancy in Europe: A Multilevel Longitudinal Analysis of Regional Disparities

Background and Objectives: The COVID-19 pandemic caused unprecedented mortality shocks worldwide, but its differential impact across European regions and the mediating mechanisms remain inadequately quantified. Materials and Methods: We conducted a longitudinal multilevel analysis using data from 29 European countries (2015–2023; N = 261 country-years). Linear mixed models estimated the impact of the pandemic on life expectancy, controlling for regional differences, vaccination rates, healthcare expenditures, gross domestic product, and excess mortality. The primary outcome was national life expectancy at birth. Results: The pandemic period was associated with an average reduction of 1.12 years in life expectancy (95% CI: 0.95 to 1.49, p < 0.001) after adjusting for pre-existing trends. Eastern Europe experienced 56% greater impact than Western Europe (interaction β = −0.623, p = 0.002). Excess mortality emerged as the primary mediator, explaining 79% of the pandemic effect. Each 1% increase in excess mortality reduced life expectancy by 0.091 years (p < 0.001). Healthcare expenditures showed protective effects (β = 0.000327 per purchasing power standards (PPS), p = 0.049), while vaccination rates, as a direct predictor, were not significantly associated with life expectancy in multivariate models. This critical finding on vaccination rates does not imply biological inefficacy but rather suggests a misspecification of its role. Conclusions: Excess mortality, rather than its direct component, COVID-19-specific mortality, appears to mediate most of the pandemic’s impact on life expectancy. Regional disparities reflect structural differences in healthcare systems and socioeconomic conditions more than differential vaccination uptake. The protective effect of vaccination on life expectancy operates entirely through the reduction in excess mortality. Consequently, health policies should prioritize strengthening resilient health systems as well as disease-specific interventions.