Explaining the Effective Reproduction Number of COVID-19 through Mobility and Enterprise Statistics: Evidence from the First Wave in Japan

Kajitani, Y.; Hatayama, M.

This study uses mobility statistics-a relatively novel data source consisting of smartphone location data-combined with business census data for the eight Japanese prefectures with the highest COVID-19 infection rates to study the effect of lockdown measures on the effective transmission rate of the virus. Based on data for the first wave of infections in Japan, we found that reductions targeting the hospitality industry were more effective than restrictions on general business activities. Specifically, we found that to fully converge the pandemic (that is, to reduce the effective reproduction number to one or less for all the days), a 40-67% reduction in weekly mobility is required, depending on the region. A lesser goal, 80% of days with one or less observed transmission, a 14-61% reduction in weekly mobility is needed.