At least 170 people have died from a new coronavirus in China following an outbreak in the central city of Wuhan, forcing a government lockdown in almost 20 cities that, in effect, has quarantined an estimated 56 million people.
More than 8,000 cases have been reported worldwide, most of them in China and especially in Wuhan and nearby cities in Hubei Province.
The infection is now more widespread than the 2002-2003 severe acute respiratory syndrome (SARS) outbreak, which also originated in China, in terms of affected people but not deaths.
Here is what you need to know:
According to the World Health Organization (WHO), coronaviruses are a family of viruses that cause illness ranging from the common cold to more severe diseases such as SARS and Middle East respiratory syndrome (MERS).
These viruses were originally transmitted between animals and people. SARS, for instance, was believed to have been transmitted from civet cats to humans while MERS travelled from a type of camel to humans.
Several known coronaviruses are circulating in animals that have not yet infected humans.
The name coronavirus comes from the Latin word corona, meaning crown or halo. Under an electron microscope, the image of the virus is reminiscent of a solar corona.
A novel coronavirus, identified by Chinese authorities on January 7 and named 2019-nCoV, is a new strain that had not been previously identified in humans.
Little is known about it, although human-to-human transmission has been confirmed.
According to the WHO, signs of infection include fever, cough, shortness of breath and breathing difficulties.
In more severe cases, it can lead to pneumonia, severe acute respiratory syndrome, kidney failure and even death.
The incubation period of the coronavirus remains unknown. Some sources say it could be between 10 and 14 days.
