The Novel Coronavirus, 2019-nCoV, is Highly Contagious and More Infectious Than Initially Estimated

Steven Sanche; Yen Ting Lin; Chonggang Xu; Ethan Romero-Severson; Nick Hengartner; Ruian Ke

We collected real-time travel data during the epidemic using the Baidu® Migration server ( Fig. 2A and Table S2 ). The server an online platform summarizing mobile phone travel data through Baidu® Huiyan [https://huiyan.baidu.com/]. Baidu® Huiyan is a widely used positioning system in China. It processes >120 billion positioning requests daily through GPS, WIFI and other means [https://huiyan.baidu.com/]. Therefore, the data represents a reliable, real-time and highresolution source of travel patterns in China. We extracted daily travel data from Wuhan to each of the provinces. We found that in general, between 40,000 to 140,000 people in Wuhan traveled to destinations outside of Hubei province daily before the lock-down of the city on January 23, with travel peaks on January 9, 21 and 22 (Fig. 2B) . Thus, it is likely that this massive flow of people from Hubei province during January facilitated the rapid dissemination of virus.