China has expanded its lockdown against a deadly new virus to an unprecedented 36 million people and rushed to build a prefabricated hospital for victims as the outbreak cast a pall over Lunar New Year, the country’s biggest holiday.

The number of confirmed coronavirus cases around the world climbed sharply to more than 1,250, with at least 41 deaths, all of them in China.

Meanwhile, France announced three cases of the virus — the first in Europe. And the United States reported its second case, involving a Chicago woman in her 60s who was taken to hospital after returning from China.

She was reported to be doing well.

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Coronavirus: how China has been affected(PA Graphics)

China’s National Health Commission reported on Saturday the number of people infected in the country had climbed to 1,287, including 237 patients who were in a serious condition.

Of the 41 deaths, 39 had occurred in central China’s Hubei province.

Transportation was shut down in Hubei’s capital Wuhan, the city of 11 million at the epicentre of the outbreak, and in at least 12 other cities in the province, encompassing a population bigger than that of New York, London, Paris and Moscow combined.

Authorities in Beijing and other cities cancelled many public celebrations and other events marking Lunar New Year, which falls on Saturday.

Hospitals in Wuhan grappled with a flood of patients and a lack of supplies.

Videos circulating online showed throngs of frantic people in masks lined up for examinations, and some complained that family members had been turned away at hospitals that were at capacity.

Authorities in Wuhan and elsewhere put out calls for medicine, disinfection equipment, masks, goggles, gowns and other protective gear.

Wuhan authorities said they are rapidly constructing a new 1,000-bed hospital to deal with the crisis, to be completed on February 3.

It will be modelled on a Sars hospital that was built in Beijing in just six days during the Sars outbreak.

The seriousness of the crisis was still an open question.

Chinese tourists wearing protective face masks in St Petersburg, Russia Chinese tourists wear protective face masks in St Petersburg, Russia (Dmitri Lovetsky/AP)

It was not clear just how lethal the virus is, or even whether it is as dangerous as ordinary flu, which kills tens of thousands of people every year in the US alone.

Scientists say it is also not clear if it spreads as easily as Sars, its genetic cousin, which also originated in China and killed about 800 people in 2002-03.

The rapid increase in reported deaths and illnesses does not necessarily mean the crisis is getting worse.

It could instead reflect better monitoring and reporting of the newly discovered virus, whose symptoms can initially resemble those of the cold and flu, including cough, fever and shortness of breath, but can worsen to pneumonia.

“It’s still too early to draw conclusions about how severe the virus is because at the beginning of any outbreak you would focus more on the severe cases,” said Tarik Jasarevic, a spokesman for the World Health Organisation in Geneva.

“And then maybe we are missing some mild cases because people will just be a little bit sick and will not have it tested. And they will recover.”

With authorities afraid that public gatherings will hasten the spread of the virus, temples locked their doors, Beijing’s Forbidden City, Shanghai Disneyland and other major tourist destinations closed, and people cancelled restaurant reservations ahead of Lunar New Year.

It is normally a time of family reunions, sightseeing trips, fireworks displays and other festivities in the country of 1.4 billion people.

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Coronavirus: confirmed cases(PA Graphics)

Wuhan’s usually bustling streets, shopping centres and other public spaces were unnervingly quiet on day two of its lockdown, and masks were mandatory in public.

Shoppers emptied store shelves, stocking up for what could be an extended period of isolation.

Karaoke bars, cinemas and internet cafes around the region were shut down.

While most of the deaths have been older patients, a 36-year-old man in Hubei died on Thursday.

The vast majority of cases have been in and around Wuhan or involved people who visited the city or had personal connections to those infected.

About two dozen cases in all have been confirmed outside mainland China, nearly all of them in Asia: Hong Kong, Macao, South Korea, Japan, Singapore, Thailand, Taiwan, Vietnam and Nepal.

Many countries are screening travellers from China and isolating anyone with symptoms.

Chinese officials have not said how long the shutdowns of the cities will last.

Recalling the government’s initial cover-up of Sars, many Chinese are suspicious of the case numbers reported by officials.

People queue up at a shopping centre in Hong KongPeople wear face masks as they queue up at a shopping centre in Hong Kong (Kin Cheung/AP)

Authorities have promised transparency.

China’s cabinet, the State Council, announced it will be collecting information on government departments that have failed in their response to the outbreak, including “delays, concealment and under-reporting of the epidemic”.

The state broadcaster CCTV’s annual Spring Festival Gala programme, which attracted more than one billion viewers last year, paid tribute to the medical workers fighting the outbreak.

“Please believe in China,” the hosts said.

“With the most transparent public information … on the battlefront of the epidemic, we will definitely win.”