On December 30, 2019, a report indicating a cluster of patients with pneumonia of unknown etiology in Wuhan City, Hubei Province, China, was published on ProMED-mail (1). It was possibly related to contact with a local fish and wild animal market (Huanan Seafood Wholesale Market), where there was also sale of live animals. Most of the first reported patients visited the market about 1 month before onset. Deep sequencing analysis from lower respiratory tract samples indicated a novel coronavirus, which was named 2019 Novel Coronavirus (2019-nCoV) by the World Health Organization (2). In mid-January 2020, China began passenger transportation during or around the Chinese New Year, which is equivalent to the Christmas holiday celebration in the West. A large number of people living in Wuhan left the region by air carrier. Since January 17, the confirmed or suspected cases have dramatically increased.