Wuhan, the Chinese city where the mystery coronavirus is believed to have broken out, has stopped public transport and flights.
Chinese state media reports that in a bid to contain the deadly virus, officials have told residents not to leave the city and that visitors must not enter.
Public transport and outgoing flights have now been halted.
Hundreds of cases of the illness have been recorded in Wuhan, located near the centre of China, east of Shangahi. It spread from there to other Chinese cities and then to other countries, including Japan, the United States and Thailand.
As of Thursday morning, it's understood there have been 517 confirmed cases of the virus, with 17 people having died. Of those, 509 of the infected are from China, as are all those killed.
The World Health Organisation (WHO) met on Thursday to decide whether to declare a global emergency. However, it said it wanted more informaiton before making such a declaration.
The director-general of WHO, Tedros Adhanom Ghebreyesus, said: "The decision about whether or not to declare a public health emergency of international concern is one I take extremely seriously, and one I am only prepared to make with appropriate consideration of all the evidence."
He thanks authorities in China for their work on looking into the illness.
Another meeting will be held on Friday to continue discussions. Officials in China are working to investigate the outbreak.
There have been fears the virus is similar to the Severe Acute Respiratory Syndrome (SARS) which killed nearly 800 people in the early 2000s.
The new coronavirus can spread by human-to-human transmission. However, little is known about the illness. There is currently no vaccine for it. Officials are now trying to understand how efficiently the virus can spread to understand its potential threat.
"We can say it is certain that it is a human-to-human transmission phenomenon," Zhong Nanshan, the scientist leading the expert panel on the oubreak, said. Two cases reported in Guangdong are believed to have come from human transmission. Medical staff there are also infected.
There are also concerns about the spread of the virus as China enters its busiest travel season with the start of the Chinese New Year. About 400 million people travel domestically and internationally during that period.
"Our commission will step up our guard during the Spring Festival, pay close attention to the development and change of the epidemic, and direct the implementation of prevention and control measures," the National Health Commission said on Monday.
Airports in China, the United States and Canada have begun screening passengers from Wuhan. However, WHO is yet to recommend any restriction to trade or travel.
"Countries are encouraged to continue strengthening their preparedness for health emergencies in line with the International Health Regulations (2005)."
WHO was first informed of cases of the virus in Wuhan on December 31. It was identified as a coronavirus on January 7.
"Common signs of infection include respiratory symptoms, fever, cough, shortness of breath and breathing difficulties. In more severe cases, infection can cause pneumonia, severe acute respiratory syndrome, kidney failure and even death," WHO says.
"Standard recommendations to prevent infection spread include regular hand washing, covering mouth and nose when coughing and sneezing, thoroughly cooking meat and eggs. Avoid close contact with anyone showing symptoms of respiratory illness such as coughing and sneezing."