We found that the population flow out of Wuhan had a long-term impact on the epidemic's spread. We examined and compared the impact of emergency response measures and population flow on China's epidemic risk after the Wuhan lockdown during the outbreak period and a control period. Because of the spatial heterogeneity, the different impacts of coupled emergency responses and population flow on the COVID-19 epidemic during the outbreak period and a control period are unclear. The local epidemic risk of COVID-19 is a combination of emergency response measures and population flow. Like the human-to-human transmission of the severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), the distribution of COVID-19 was driven by population flow and required emergency response measures to slow down its spread and degrade the epidemic risk.
Coronavirus disease 2019 (COVID-19) has spread around the world and requires effective control measures.
