その他 (国内) Non-Compulsory Measures Sufficiently Reduced Human Mobility in Japan during the COVID-19 Epidemic

Takahiro Yabe (Purdue University), Kota Tsubouchi, Naoya Fujiwara (Tohoku University), Takayuki Wada (Osaka City University), Yoshihide Sekimoto (The University of Tokyo), and Satish V. Ukkusuri (Purdue University)


Large-scale mobility data collected from mobile phones provide us with an opportunity to monitor and understand the impacts of non-pharmaceutical interventions during the COVID-19 outbreak with an unprecedented spatio-temporal granularity and scale. While such data has been used in various countries, the changes in mobility patterns in Japan where interventions were limited to non-compulsory measures, has been under-studied. Here, we analyzed the temporal changes in i) human mobility behavior changes, ii) rates of social contacts, and iii) correlations of such mobility changes with the transmissibility of COVID-19, using anonymized large scale mobility data collected from more than 200K mobile phones in Tokyo, Japan. Our analysis concludes that by April 15th (1 week from declaring state of emergency), human mobility behavior had decreased by around 50%, resulting in a 70% reduction of social contacts in Tokyo, showing the effectiveness of non- compulsory measures. Furthermore, the reduction in human mobility metrics and social contact measures showed significant correlation with the decrease of the effective reproduction number of COVID-19.