| Socio-demographic variables |
Population density (persons/km2) |
Household registered population in the city/area of the city |
| Family size (persons) |
Average household size |
| Proportion of elderly people(%) |
The ratio of the older people(aged 60 and above) in the city |
| GDP per capita (yuan) |
Gross regional domestic product by its total population |
| Environmental variables |
Urban road density(km/km2) |
The total length of roads in the urban area/urban area of the city |
| Area of city(km2) |
The area of administrative boundary of the city |
| Density of designated hospitals |
Density of designated hospitals for diagnosing the COVID-19 infection |
| Total movement from Wuhan |
The volume of traffic from Wuhan to the city between January 1 and January 23 (mobile-phone-data-based) |
| Policy variables |
Timing of Level 1 response |
Number of days between the implementation of Level 1 response and January 23 |
