Human mobility and COVID-19 initial dynamics

TL;DR

This study demonstrates that human mobility data can explain up to 92% of the initial COVID-19 spread in EU countries, highlighting the effectiveness of mobility restrictions and the importance of internal mobility in controlling the pandemic.

Contribution

It provides a systematic analysis linking mobility data with COVID-19 spread at a European level, using excess deaths and antibody data, and shows the potential for extending this approach to other countries.

Findings

Mobility explains up to 92% of initial virus spread in France and Italy.

Mobility restrictions contributed to saving lives by reducing spread.

Internal mobility has a greater impact than cross-regional mobility.

Abstract

Mobility data at EU scale can help understand the dynamics of the pandemic and possibly limit the impact of future waves. Still, since a reliable and consistent method to measure the evolution of contagion at international level is missing, a systematic analysis of the relationship between human mobility and virus spread has never been conducted. A notable exceptions are France and Italy, for which data on excess deaths, an indirect indicator which is generally considered to be less affected by national and regional assumptions, are available at department and municipality level, respectively. Using this information together with anonymised and aggregated mobile data, this study shows that mobility alone can explain up to 92% of the initial spread in these two EU countries, while it has a slow decay effect after lockdown measures, meaning that mobility restrictions seem to have effectively contribute to save lives. It also emerges that internal mobility is more important than mobility across provinces and that the typical lagged positive effect of reduced human mobility on reducing excess deaths is around 14-20 days. An analogous analysis relative to Spain, for which an IgG SARS-Cov-2 antibody screening study at province level is used instead of excess deaths statistics, confirms the findings. The same approach adopted in this study can be easily extended to other European countries, as soon as reliable data on the spreading of the virus at a suitable level of granularity will be available. Looking at past data, relative to the initial phase of the outbreak in EU Member States, this study shows in which extent the spreading of the virus and human mobility are connected.