The new coronavirus has caused alarm because it is still too early to know just 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:
* Chinese state television reports there are 634 cases in China. Authorities have confirmed 18 deaths.
* 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 four cases, Japan and Vietnam two apiece, and South Korea, Taiwan, Singapore and the United States one each. A second possible case was being tested in the United States and the BBC reported five people being tested in Scotland. Patients in these cases were either residents of Wuhan or recent visitors to the city.
* The World Health Organisation says while the outbreak is an emergency for China and the agency is tracking the evolution 'every minute', it's not yet a global health emergency.
* Symptoms include fever, cough and difficulty breathing.
* China says the virus is mutating and that there is evidence of respiratory transmission.
* Those most affected are older people and those with underlying health conditions.
* Three research teams are to start work on developing potential vaccines, the Coalition for Epidemic Preparedness Innovations said. The plan is to have at least one potential vaccine in clinical trials by June.
* Preliminary research suggests the virus was passed to humans from snakes, but Chinese government medical adviser Zhong Nanshan has also identified badgers and rats as possible sources.
* Wuhan, a city of 11 million people, is in lockdown, with urban transport shut and outgoing flights suspended.
* Nearby Huanggang, a city of 7 million people, is suspending public transport and closing public venues, including movie theatres and internet cafes.
* Beijing closed tourist access to the Forbidden City and cancelled large gatherings, including two Lunar New Year temple fairs.
* Airports around the world have stepped up screening of passengers who have travelled to China.
* Equities markets around the world fell on Thursday, led by the biggest decline in Chinese stocks in more than eight months, as concern mounted about the spread of the virus.
Australian Associated Press