Wu JT, et al. - Researchers tried to calculate the size of the epidemic in Wuhan based on the number of cases exported from Wuhan to cities outside mainland China and determine the extent of the domestic and global public health risks of epidemics, accounting for social and non-pharmaceutical prevention interventions. In this study, data were applied between Dec 31, 2019, and Jan 28, 2020, on the number of cases exported from Wuhan internationally (known days of symptom onset from Dec 25, 2019, to Jan 19, 2020) to infer the number of infections in Wuhan from Dec 1, 2019, to Jan 25, 2020. This study calculated the national and global spread of 2019-nCoV, accounting for the impact of the metropolitan-wide quarantine of Wuhan and surrounding cities, which began Jan 23–24, 2020. Data was utilized on monthly flight bookings from the Official Aviation Guide and data on human mobility across more than 300 prefecture-level cities in mainland China from the Tencent database. It was noted that other major Chinese cities are probably sustaining localized outbreaks, given that 2019-nCoV is no longer contained within Wuhan. The data demonstrated that large cities overseas with close transport links to China could also become outbreak epicenters unless substantial public health interventions at both the population and personal levels are implemented immediately. It is indicated that independent self-sustaining outbreaks in major cities globally could become inevitable because of substantial exportation of presymptomatic cases and in the absence of large-scale public health interventions.