The World Health Organization declared the outbreak sparked by a new virus in China that has been exported to more than a dozen countries as a global emergency Thursday after the number of cases spiked more than tenfold in a week.
The UN health agency defines an international emergency as an "extraordinary event" that constitutes a risk to other countries and requires a coordinated international response.
China first informed WHO about cases of the new virus in late December. To date, China has reported more than 7,800 cases including 170 deaths. Eighteen other countries have since reported cases, as scientists race to understand how exactly the virus is spreading and how severe it is.