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 including the United States
Chinese authorities rapidly expanded a mammoth quarantine effort aimed at containing a deadly contagion on Friday to 13 cities and a staggering 41 million people, as nervous residents were checked for fevers and the death toll climbed to 26.
While the World Health Organization (WHO) held off on declaring a global emergency despite confirmed cases in half a dozen other countries, China expanded its lockdown to cover an area with a total population greater than Canada's.
A range of Lunar New Year festivities have been cancelled, while temporary closures of Beijing's Forbidden City, Shanghai's Disneyland and a section of the Great Wall were announced 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 WHO said China faced a national emergency but stopped short of making a declaration that 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 including the United States.
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.
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 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.
"I don't know the results yet."
With hundreds of 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. Deepening the isolation, there were few flights 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.
But he said a prolonged shutdown should not pose food-shortage problems because many Chinese had stocked up for the holiday.
Besides Wuhan, 12 other smaller cities nearby have battened down the hatches, with most of them going public on Friday with various measures ranging from closing public venues and restricting large gatherings to halting public transportation and asking citizens not to leave their cities.
Several of the cities have populations numbering several million, led by Huanggang, which has 7.5 million.
The pathogen - 2019 Novel Coronavirus (2019-nCoV) - has caused many outlets in Shanghai, Beijing and other cities to sell out their stocks of face masks.
As reports surfaced of bed shortages in Wuhan hospitals, state media said authorities were rushing to build a new facility devoted to the outbreak in a mind-blowing 10 days.
The Wuhan hospital is targeted to be ready by February 3. Dozens of excavators and trucks were filmed working on the site by state television.
State broadcaster CCTV also reported that 40 medical doctors from the military were being brought in to help with intensive care.
In addition, 405 medical workers were being sent to Wuhan from Shanghai, said state news agency Xinhua, with the first set of 135 flying in Friday night.
Yesterday, staff in full body protective suits were seen checking the temperatures of people entering a subway station in Beijing.
Thermal cameras scanned passengers arriving at Beijing's West Railway Station.
'Work as one'
Chinese authorities said the number of cases leapt overnight to more than 800, with 177 in serious condition. There were another 1,072 suspected cases.
Officials also said that a virus patient died in Heilongjiang province in China's far northeast, the second death outside the Wuhan epicentre.
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.
"If we all work as one, we can contain the virus in Wuhan and add no more cases exported from Wuhan, so as to stem the virus nationwide," Gao told state TV.
Beijing has cancelled popular New Year public events at temples in the capital, the historic Forbidden City will close from today, and Shanghai Disneyland said it also will shut down for an indefinite period from today to protect visitors and staff.
A number of tourist spots were closed and events cancelled in central Hunan province, which borders Hubei province.
The crisis was given a prominent spot on the celebrated gala show on state TV yesterday evening, the traditional Lunar New Year's Eve extravaganza broadcast by CCTV watched by hundreds of millions of Chinese.
The host told Wuhan medical staff "We love you" against a backdrop of hospital footage and stirring music.