Mobility between the four Nordic and the other countries, represented by lines connecting the origin and destination. Credit: PLOS Computational Biology (2024). DOI: 10.1371/journal.pcbi.1012182 As COVID-19 spread globally in 2020, many countries swiftly closed their borders to prevent the disease from entering. However, there was little scientific evidence to support the effectiveness of such measures. While post-COVID research has extensively focused on the efficacy of internal travel restrictions, cross-border travel has received less attention due to challenges in accessing quality data. In a major multidisciplinary collaboration effort across Finland, Sweden, Read More