How does the outbreak of 2019-nCoV spread in mainland China? A retrospective analysis of the dynamic transmission routes

Xiandeng Jiang; Le Chang; Yanlin Shi

Coronaviruses are single-stranded, enveloped and positive-sense RNA viruses, which are spherical in shape and have petal-like spines [1] . Firstly discovered and identified in 1965 [2] , coronaviruses have not caused large-scale outbreaks until the 2003 SARS epidemic in China, followed by 2012 MERS in Saudi Arabia and 2015 MERS in South Korea [3] . Although the exact origin remains debatable [4] , the fourth outbreak has taken place in Hubei province of China in December 2019 and rapidly spread out nationally [5] [6] [7] [8] [9] [10] . On January 10, 2020, the WHO officially named this new coronavirus as the 2019 novel coronavirus, or 2019-nCoV, and released a comprehensive interim guidance on dealing with this new virus for all countries [11] . As of February 19, there are 75,101 confirmed cases (including 2,121 death report) in China, among which over 80% are from Hubei and over 50% are from Wuhan, the capital city of Hubei [12] .