The influence of cross-border mobility on the COVID-19 epidemic in Nordic countries

Abstract

AbstractRestrictions of cross-border mobility are typically used to prevent an emerging disease from entering a country in order to slow down its spread. However, such interventions can come with a significant societal cost and should thus be based on careful analysis and quantitative understanding on their effects. To this end, we model the influence of cross-border mobility on the spread of COVID-19 during 2020 in the neighbouring Nordic countries of Denmark, Finland, Norway and Sweden. We investigate the immediate impact of cross-border travel on disease spread and employ counterfactual scenarios to explore the cumulative effects of introducing additional infected individuals into a population during the ongoing epidemic. Our results indicate that border restrictions can significantly influence the course of an epidemic, but this impact is highly contingent on the prevailing epidemic status of the involved countries. In particular, there are several instances in which the contribution of cross-border movement was found to be negligible. Our findings underscore the critical importance of accurate data and models on both epidemic progression and travel patterns in informing decisions related to inter-country mobility restrictions.