China is battling to contain a deadly coronavirus in Hubei province, as hundreds of millions of Chinese prepare to celebrate the Lunar New Year.
Beijing and Hong Kong have cancelled some major festivities to prevent large crowds gathering.
Wuhan and other cities in Hubei have seen far more draconian measures, with public transport suspended.
On Friday, Chinese authorities said the death toll had risen to 25, with 830 confirmed cases.
Of the confirmed cases, 177 were in a serious condition and 34 have been "cured and discharged", the National Health Commission said.
There are also 1,072 suspected cases, it added. Almost all of the deaths have been in Hubei - the virus emerged in the province's capital, Wuhan.
The World Health Organization has not classed the virus as an "international emergency", partly because of the low number of overseas cases - currently 13.
"It may yet become one," said the WHO's director-general, Dr Tedros Adhanom Ghebreyesus.
The US said on Thursday it was investigating its second suspected case.
What are the fears for Lunar New Year?
It is one of the world's largest annual migrations of people, with millions of people returning to their hometowns to celebrate.
The authorities have cancelled all large-scale celebrations in Beijing. Temple fairs are banned, film releases postponed and the Forbidden City will be closed to the public.
Hong Kong cancelled an international carnival and an annual football tournament.
China has effectively quarantined nearly 20 million people in Hubei province, with no planes or trains in or out of Wuhan. Roadblocks have also been reported.
There have been long queues - and some squabbling - at food stores for diminishing stocks.
Face masks are compulsory in all public places in Wuhan and some residents are saying it is like a ghost town.
The BBC's Stephen McDonell, in Beijing, says that many hundreds of thousands of residents have already left Wuhan to celebrate the Lunar New Year elsewhere.
With an incubation period of around five days, he said they may have passed on the virus without even knowing it.
What's the global situation?
Vietnam and Singapore were on Thursday added to the nations and overseas territories recording confirmed cases, joining Thailand, the US, Taiwan and South Korea.
Japan confirmed its second case on Thursday and South Korea its second case on Friday.
There are only 13 such cases overall, with Thailand's four the most of any nation other than China.
Other nations are investigating suspected cases, including the UK and Canada.
On Thursday, US authorities said a second suspected case was being investigated, in the state of Texas.
A health official said the patient had travelled from Wuhan and was a student at Texas A&M University, north of Houston.
The only confirmed case in the US so far is a man in Seattle, Washington state. He is said to be recovering and is due to be released from hospital.
Many authorities have announced screening measures for passengers from China, including on Thursday the major airport hubs of Dubai and Abu Dhabi.
Taiwan has banned people arriving from Wuhan and the US state department warned American travellers to exercise increased caution in China.
Why is this not a global emergency?
Analysis by James Gallagher, BBC health and science correspondent
The view of the WHO's emergency committee was "now is not the time". Two reasons were cited: the limited number of cases abroad and the "efforts made by China".
The latter seems to be a nod to the lockdown of multiple cities in the past 24 hours, which should minimise the risk of the virus becoming a global problem. But it may yet become one.
Some scientific details were also released, with the WHO saying 25% of reported cases were developing severe symptoms.
And there were two clues on how infectious the novel coronavirus is.
There is a preliminary estimate of the average number of people each infected person passes the virus on to (known as the R0 value) of between 1.4 and 2.5.
Any number greater than one means the virus has the potential to spread in the population, but this is lower than the figure for Sars.
And in Wuhan a "fourth-generation case" has been detected - this is a sustained chain of transmission involving four people.
It remains too early to call the true extent of human-to-human transmission.
BDST: 1058 HRS, JAN 24, 2020