The US advised against all travel to China on Friday after the World Health Organization declared the outbreak of a new virus that has spread to more than a dozen countries a global emergency. The number of cases spiked more than tenfold in a week, including the highest death toll in a 24-hour period reported Friday.

The State Department's travel advisory told Americans currently in China to consider departing using commercial means, and requested that all non-essential US government personnel defer travel 'in light of the novel coronavirus.'

China counted 9,692 confirmed cases with a death toll of 213, including 43 new fatalities. The vast majority of the cases have been in Hubei province and its provincial capital, Wuhan, the epicenter of the outbreak. No deaths have been reported outside China.

Meanwhile, China's foreign ministry said it will send charter flights to bring home residents of Hubei from overseas.

The one-sentence statement gave few details, but said those from Hubei and especially Wuhan would be sent directly back to Wuhan as soon as possible in light of the 'practical difficulties' they were encountering.

China has placed more than 50 million people in the region under virtual quarantine, while foreign countries have cut back severely on travel to the country and quarantined those who recently passed through Wuhan. The virus is believed to have a two-week incubation period, during which those infected can pass on the illness even if they show no symptoms such as fever and cough.

In the seven days ending at midnight Thursday, the National Health Commission reported 596 cases have been 'cured and discharged from hospital.'

The UN health agency defines an international emergency as an 'extraordinary event' that constitutes a risk to other countries and requires a coordinated international response.

China first informed WHO about cases of the new virus in late December. Eighteen other countries have since reported cases, as scientists race to understand how exactly the virus is spreading and how severe it is.

Experts say there is significant evidence the virus is spreading among people in China and have noted with concern instances in other countries — including the United States, France, Japan, Germany, Canada, South Korea and Vietnam — where there have also been isolated cases of human-to-human transmission.

On Friday, the US Embassy in Beijing said it was authorizing the departure of family members and all non-emergency US government employees from Beijing and the consulates in the cities of Chengdu, Guangzhou, Shanghai, and Shenyang. Staff from the Wuhan consulate departed earlier this week.

The decision was made 'out of an abundance of caution related to logistical disruptions stemming from restricted transportation and availability of appropriate health care related to the novel coronavirus,' the embassy said.

The level 4 'Do Not Travel' advisory is the highest grade of warning.

Mike Wester, an American businessman in Beijing who has lived in China for 19 years, said he has no plans to leave.

'I feel safer self-quarantining myself here at home than I do risking travel,' said Wester.

He pointed to potential risks from crowds at airports and being required to remove a mask for passport and security checks.

Speaking by Skype from Utah, Kelly Flanagan, 36, a school counselor in China since 2011, said she is planning to stay out of China as she watches the virus spread.

'This is probably going to be awhile,' said Flanagan, who said her Type 1 diabetes added to her health concerns. From the US she is working remotely with her students to help them pass English proficiency exams.

Among other countries, Japan advised against travel to China and Britain against 'all but essential travel' to the country, not including Hong Kong and Macao. British Airways has already suspended all flights to and from mainland China.

'If you feel that you may want to leave China soon, you should consider making plans to do so before any further restrictions may be imposed,' the Foreign and Commonwealth Office said in a statement.

Speaking to reporters in Geneva on Thursday, WHO Director-General Tedros Adhanom Ghebreyesus noted the worrisome spread of the virus between people outside China.

'The main reason for this declaration is not because of what is happening in China but because of what is happening in other countries,' he said. 'Our greatest concern is the potential for this virus to spread to countries with weaker health systems which are ill-prepared to deal with it.'

'This declaration is not a vote of non-confidence in China,' he said. 'On the contrary, WHO continues to have the confidence in China's capacity to control the outbreak.'

A declaration of a global emergency typically brings greater money and resources, but may also prompt nervous governments to restrict travel and trade to affected countries. The announcement also imposes more disease reporting requirements on countries.

China's UN Ambassador Zhang Jun said Thursday evening in New York that 'we are still at a very critical stage in fighting the coronavirus' but stressed that the epidemic is still mainly confined to China and urged the international community against any overreaction.

Zhang told reporters 'we are still making our assessment' of the WHO declaration.

'While we understand the concerns of other countries, we should also listen to advice of the director-general of WHO' who said he had full confidence in China's efforts in fighting the epidemic and 'there is no reason for measures that unnecessarily interfere with the international travel and trade,' Zhang said.

He said China appreciated 'the friendly gesture made by the international community' in providing medical equipment, and 'what are needed urgently,' especially in Hubei province, are masks and other protective medical supplies including glasses.

In the wake of numerous airlines cancelling flights to China and businesses including Starbucks and McDonald's temporarily closing hundreds of shops, Tedros said WHO was not recommending limiting travel or trade to China.

'There is no reason for measures that unnecessarily interfere with international travel and trade,' he said. He added that Chinese President Xi Jinping had committed to help stop the spread of the virus beyond its borders.

Although scientists expect to see limited transmission of the virus between people with close contact, like within families, the instances of spread to people who may have had less exposure to the virus in Japan and Germany is worrying.

In Japan, a man in his 60s caught the virus after working as a bus driver for two tour groups from Wuhan. In Germany, a man in his 30s was sickened after a Chinese colleague from Shanghai, whose parents had recently visited from Wuhan, came to his office for a business meeting. Four other workers later became infected. The woman had shown no symptoms of the virus until her flight back to China.

'That's the kind of transmission chain that we don't want to see,' said Marion Koopmans, an infectious diseases specialist at Erasmus University Medical Center in the Netherlands and a member of WHO's emergency committee.

The new virus has now infected more people in China than were sickened there during the 2002-2003 outbreak of SARS, or Severe Acute Respiratory Syndrome, a cousin of the new virus. Both are from the coronavirus family, which also includes those that can cause the common cold.