What Roles Do Population and Migration Flows Play in the Spatial Diffusion of COVID-19 from Wuhan City to Provincial Regions in China?

Population flow and migration flow are related but different. This research demonstrates the important roles of population and migration flows in the spatial diffusion of COVID-19 in mainland China using statistical analysis. Visitors are often considered responsible for the spread of COVID-19. Many migrants traveled back to their hometown from Wuhan city before 23 January 2020 for the spring holiday. They had stayed in Wuhan for a long time and had a higher risk to be infected than other short-term visitors. Thus previous migration flow is expected to have an indirect impact on the spatial diffusion of COVID-19 via population flow. It is found that the migration flows in 2005-2010 and 2010-2015 generally had larger correlation coefficients than real-time population flows based on big data on any day during 10-22 January 2020 with the number of COVID-19 cases. The average population flow in 8 days also had high correlation coefficients with the number of COVID-19 cases. The weighted average share of population flow and migration flow had the highest correlation coefficient with the number of COVID-19 cases on 26 January 2020. The COVID-19 risk for a migrant and a resident from an affected area could be 9 times that for a visitor.