The atypical pneumonia case, caused by a novel coronavirus (2019-nCoV), was first identified and reported in Wuhan, China in December, 2019 [1]. As of January 21, 2020 (11:59 a.m., GMT+8), there have been 215 cases of 2019-nCoV infections confirmed in mainland China. There were 198 domestic cases in Wuhan including 4 deaths, and 17 cases identified outside Wuhan including 8 in Shenzhen, 5 in Beijing, 2 in Shanghai and 2 in other places. The 2019-nCoV cases were also reported in Thailand, Japan and Republic of Korea, and all these cases were exported from Wuhan China, see WHO news release https://www.who.int/csr/don/en/from January 14–20, 2020. The first case outside Wuhan was confirmed in Shenzhen on January 3, 2020. Then, many major Chinese cities reported events of ‘imported 2019-nCoV cases’, thereafter, including Beijing and Shanghai. The outbreak is still on-going. And a recently published preprint by Imai et al. estimated that a total of 1723 (95%CI: 427–4471) cases of 2019-nCoV infections in Wuhan had onset of symptoms by January 12, 2020 [2].