On the interplay of regional mobility, social connectedness, and the spread of COVID-19 in Germany

Since the primary mode of respiratory virus transmission is person-to-person interaction, we are required to reconsider physical interaction patterns to mitigate the number of people infected with COVID-19. While non-pharmaceutical interventions (NPI) had an evident impact on national mobility patterns, only the relative regional mobility behaviour enables an unbiased perspective on the effect of human movement on the spread of COVID-19. In this paper, we therefore investigate the impact of human mobility and social connectivity derived from Facebook activities on the weekly rate of new infections in Germany between March 3rd and June 22nd, 2020. Our results confirm that reduced social activity lowers the infection rate, accounting for regional and temporal patterns. The extent of social distancing, quantified by the percentage of people staying put within a federal administrative district, has an overall negative effect on the incidence of infections. Additionally, our results show spatial infection patterns based on geographic as well as social distances. Accepted at Journal of Royal Statistical Society, Series A