Air travel-induced COVID-19 risk and mortality across US counties

This study investigates the impact of air travel-induced COVID-19 importation risk on COVID-related mortality across US counties from January 2020 to December 2021. We construct a novel measure of relative risk of COVID-19 importation for each destination county, based on passenger flows from origin counties, the severity of local outbreaks, and the presence of active cases. Using county-level data on COVID-19 mortality, vaccination rates, demographic characteristics, and socioeconomic factors, we find a significant association between higher importation risk and increased COVID-19 mortality. The results suggest that air travel plays a crucial role in shaping the spatial distribution of COVID-19 mortality, underlining the need for targeted public health interventions in high-risk areas. Moreover, we conduct robustness checks using an alternative measure of mortality, confirming the consistency of these results.