Epidemiology and Transmission of COVID-19 in Shenzhen China: Analysis of 391 cases and 1,286 of their close contacts

Qifang Bi; Yongsheng Wu; Shujiang Mei; Chenfei Ye; Xuan Zou; Zhen Zhang; Xiaojian Liu; Lan Wei; Shaun A Truelove; Tong Zhang; Wei Gao; Cong Cheng; Xiujuan Tang; Xiaoliang Wu; Yu Wu; Binbin Sun; Suli Huang; Yu Sun; Juncen Zhang; Ting Ma; Justin Lessler; Teijian Feng

If well tracked, early introductions of an emerging pathogen provide a unique opportunity to characterize its transmission, natural history, and the effectiveness of screening. The careful monitoring of cases and low probability of infection from the general community enables inferences, critical to modeling the course of the outbreak, that are difficult to make during a widely disseminated epidemic. In particular, we are able to make assumptions about when and where cases were likely infected that are impossible when the pathogen is widespread. Furthermore, during these early phases, uninfected and asymptomatic contacts are often closely tracked, providing critical information on transmission and natural history. Combined, this data on early introductions can be used to give insights into disease natural history 9 , transmission characteristics 10 , and the unseen burden of infection 11 .