A massive quarantine effort covering 13 cities was in effect in China on Saturday aimed at containing a deadly virus, as the death toll climbed to 26 and the first cases of the disease were reported in Europe and South Asia.
China on Friday imposed transport bans in an area covering a staggering 41 million people, as the United States confirmed its second case of the SARS-like virus that has reached almost a dozen countries.
The virus has also spread to densely populated South Asia, where Nepal confirmed one case, and Europe, where two cases were reported in France.
With more than 800 cases logged in China so far, a range of Lunar New Year festivities have been cancelled, with temporary closures of Beijing's Forbidden City, Shanghai's Disneyland and a section of the Great Wall to prevent the disease from spreading further.
The previously unknown virus has caused alarm because of its similarity to SARS (Severe Acute Respiratory Syndrome), which killed hundreds across mainland China and Hong Kong in 2002-2003.
The World Health Organization said China faced a national emergency but stopped short of declaring a global health emergency, which would have prompted greater global cooperation.
The outbreak emerged in late December in Wuhan, an industrial and transport hub of 11 million people in China's centre, spreading to several other countries.
In the United States, a woman in Chicago became the second known patient on US soil, with 50 other suspected cases under investigation. A city health official said on Friday the woman was doing well and in stable condition.
Hours after the announcement President Donald Trump thanked Chinese President Xi Jinping via Twitter "on behalf of the American People" for his country's "efforts and transparency" in working to contain the virus.
"It will all work out well," Trump wrote.
The first case in South Asia was reported in Nepal on Friday. The 32-year-old male patient, who had arrived from Wuhan, was treated at a hospital in Kathmandu and discharged, officials said.
And two cases were confirmed in France, the first in Europe. Both had recently travelled to China and have been placed in isolation, the country's health minister said.
China is in the midst of its Lunar New Year holiday, a typically joyous time of family gatherings and public festivities.
But on Friday Wuhan was a ghost town, its streets deserted and stores shuttered.
As reports surfaced of bed shortages in Wuhan for the sick, state media said authorities were rushing to build a new hospital only for the outbreak in a mind-blowing 10 days.
Hospitals visited by AFP journalists bustled with worried patients being screened by staff wearing full-body protective suits.
At a temperature-check station, a medical staffer in a bodysuit, face mask and goggles took a thermometer from a middle-aged woman, pausing to examine the reading before quickly turning back to the patient.
"Have you registered? Then go and see the doctor," the staffer said.
One 35-year-old man surnamed Li voiced the fears of many. "I have a fever and cough, so I'm worried that I'm infected," he said.
With millions of people on the move across China for the holiday, the government has halted all travel out of Wuhan, shut down its public transport and told residents to stay home. Few flights were available to the city.
"This year we have a very scary Chinese New Year. People are not going outside because of the virus," a taxi driver in the city, who asked not to be named, told AFP.
He said a prolonged shutdown should not pose food-shortage problems because many Chinese had stocked up for the holiday.
Besides Wuhan, 12 smaller cities nearby have battened down the hatches, with most announcing measures Friday that include closing public venues, restricting large gatherings and halting public transportation, as well as urging citizens not to travel.
Several of the cities have populations numbering several million, led by Huanggang with 7.5 million.
The pathogen -- 2019 Novel Coronavirus (2019-nCoV) -- has caused many outlets in Shanghai, Beijing and other cities to sell out of face masks.
State broadcaster CCTV reported that 40 military medical doctors were being deployed to Wuhan to help with intensive care.
In addition, 405 medical workers were being sent to Wuhan from Shanghai, said state news agency Xinhua.
In Beijing, staff in full-body protective suits were seen Friday checking the temperatures of people entering a subway station.
Thermal cameras also scanned passengers arriving at Beijing's West Railway Station.
Beijing has been praised for its response in contrast to SARS, when it took months to report the disease and initially denied WHO experts any access.
Gao Fu, head of the Chinese Center for Disease Control and Prevention, asked China's people to forego New Year gatherings this year and confine themselves at home until the all-clear.