The coronavirus has caused alarm because it is still too early to know how dangerous it is and how easily it spreads between people. And because it is new, humans have not been able to build any immunity to it.
WHAT WE KNOW SO FAR:
* The death toll in China has risen to 42, authorities reported. Some 1372 people in China have been infected with the virus.
* China has announced further travel curbs. Ride-hailing giant Didi Chuxing says it's halting inter-city services to and from Beijing, while the capital will also stop running inter-province shuttle buses.
* The previously unknown strain is believed to have emerged late last year from illegally traded wildlife at an animal market in Wuhan.
* Thailand has reported five cases; Australia has reported four; Singapore, France, Japan, Taiwan and Malaysia three; Vietnam, South Korea and the United States two apiece; and Nepal one.
* The World Health Organisation says while the outbreak was an emergency for China, it's not yet a global health emergency.
* Symptoms include fever, cough and difficulty breathing.
* China says the virus is mutating and can be transmitted through human contact.
* Those most affected are older people and those with underlying health conditions.
* Three research teams have begun work on developing potential vaccines, the Coalition for Epidemic Preparedness Innovations said. Scientists hope to be testing the first possible vaccines in three months' time.
* Wuhan, a city of 11 million, is under severe travel restrictions, with urban transport shut and outgoing flights suspended.
* China has advised people to avoid crowds and more than 10 cities in the central province of Hubei, where Wuhan is located, have suspended some transport.
* Beijing closed tourist access to the Forbidden City and cancelled large gatherings, including two Lunar New Year temple fairs, and closed part of the Great Wall.
* Starbucks has closed all shops and suspended delivery services in China's Hubei province for the week-long Lunar New Year holiday, following a similar move by McDonald's in five Hubei cities.
* Walt Disney Co's Shanghai Disney Resort is closed.
* Hong Kong has declared an emergency and will extend school holiday closures until February 17. The city also cancelled all official Lunar New Year celebrations and official visits to mainland China.
* China's Haikou city, capital of the southern island province of Hainan, started a 14-day centralised medical observation for tourists from Hubei. Sanya city in the province, a popular vacation destination, has shut all tourist sites.
* Airports around the world have stepped up screening.
* Shares and crude prices fell sharply on Friday as investors moved into safe-haven assets amid concerns that the virus could curb travel and hurt economic demand.
* Some experts believe the virus is not as dangerous as the 2002-03 Severe Acute Respiratory Syndrome (SARS) that killed nearly 800 people, and Middle East Respiratory Syndrome (MERS), which has killed more than 700 people since 2012.
* Each person infected is passing the disease on to between two and three other people on average at current transmission rates, according to two separate scientific analyses.
Australian Associated Press