The World Health Organization has declared an outbreak of a new coronavirus from Wuhan, China, to be a public health emergency of international concern.
WHO officials made the announcement Thursday following an emergency committee meeting of health experts on the virus.
This was the second time the WHO met to discuss the issue. After a two-day meeting on Jan. 22 and 23, the committee declined to declare an emergency.
Since then, the number of confirmed cases has exploded to over 8,000, with 170 confirmed deaths, according to data compiled by researchers at Johns Hopkins University.
Most cases and all deaths so far have been in China, where the outbreak is suspected to have started around the city of Wuhan.
Cases have been reported in 21 other countries, including Canada, which has three confirmed cases of the virus.
The virus causes a fever, cough and, in some cases, difficulty breathing.
The new coronavirus can be transmitted from person to person, although it is not clear how easily that happens. Most cases so far are in people who have been in Wuhan, family members of those infected or medical workers.
Transmission is most likely through close contact with an infected person via particles in the air from coughing or sneezing, or by someone touching an infected person or object with the virus on it and then touching their mouth, nose or eyes.
In order to reduce the likelihood of transmission, the WHO recommends that people frequently wash their hands, cover their mouth and nose when sneezing or coughing, and avoid close contact with those who are sick.
It is unclear how deadly the new virus is. Although severe cases can cause pneumonia and death, there may be many cases of milder disease going undetected. Many of those who have died had pre-existing medical conditions, were elderly or had weakened immune systems.
Declarations of a “Public Health Emergency of International Concern” are relatively rare.