Estimating Subnational Excess Mortality in Times of Pandemic. An Application to French Departements in 2020 (and 2021)

Carlo Giovanni Camarda , Institut National d'Études Démographiques (INED)
Florian Bonnet, Institut National d'Études Démographiques (INED)

The COVID-19 pandemic did not affect European subnational regions in a uniform way. Within a country like France, Brittany seems to have been spared while Île-de-France suffered a heavy toll. Knowledge of the impact of the Covid-19 pandemic on mortality at the local level is therefore an important issue today. Vital statistics are now available for a large number of countries for 2020, and allow the calculation of national excess mortality. Excess mortality is defined as the difference between the mortality observed during the pandemic and the mortality that would have been observed in the absence of a pandemic. The calculation of excess mortality at the local level has two important methodological challenges: (1) it requires appropriate mortality projection models; (2) small populations in some areas implies consequential uncertainty in the estimates. In this paper, we address both issues by proposing a method that ``coherently'' forecast mortality for sub-national areas and by incorporating uncertainty in the computation of life tables measures. We thus achieve an accurate uncertainty estimation of regional excess mortality for all ages. We apply our approach to French départements (NUTS 3, 95 geographical units) in 2020 (and later 2021) for both sexes. However, flexibility and availability of the proposed method allows to estimate excess mortality in many European subnational regions.

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 Presented in Session 14. COVID-19 mortality across groups and subpopulations