Population movement, city closure and spatial transmission of the 2019-nCoV infection in China

Siqi Ai; Guanghu Zhu; Fei Tian; Huan Li; Yuan Gao; Yinglin Wu; Qiyong Liu; Hualiang Lin

Similarly, we evaluated the impacts of one-day and two-day delayed city closure. We 129 took the average index of the population outflow between Jan 21 and 23 as the daily 130 index of population outflow before the city closure, and used the same calculation 131 method to estimate the index of population outflow within Wuhan increased by the 132 delayed city closure on Jan 24 and Jan 25 (the delayed outflow index). We multiplied 133 the delayed outflow index by the average proportion and one corresponding unit to 134 estimate the increased number of cases caused by one-day and two-day delayed city 135 closure in each province. Our study provided timely evidence for the formulation of efficient strategies to 253 prevent diseases from spreading out. On the one hand, the result could help assess 254 effectiveness of the prevention and control efforts. For example, the cases in Zhejiang 255 and Guangdong are apparently more than estimated, which indicated a better health 256 emergency response system (i.e. higher detection efficiency) or inadequate isolation. 257