[Challenges to prevent and control the outbreak of COVID-19]

An outbreak of severe pneumonia of unknown cause was reported in December 2019 in Wuhan, Hubei province, China. The infectious virus was soon identified and named as 2019 novel coronavirus (2019-nCoV). The name of the COVID-19 was given by WHO on 11 February 2020. It has so far caused about 118 000 cases in 114 countries including China ending March 10, and was characterized as a pandemic by WHO on March 11. We still face great challenges in control of the epidemic: uncertain initial source of infection, infected populations widely scattered, complex routs of transmission, populations generally susceptible, high contagiousness of the virus, and finally vaccines unlikely available in the near future.