BEIJING (AP) — The U.S. 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 U.S. government personnel defer travel “in light of the novel coronavirus.”

“Travelers should be prepared for travel restrictions to be put into effect with little or no advance notice. Commercial carriers have reduced or suspended routes to and from China,” it said.

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.

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

The U.N. 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.

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 U.N. 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, 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.

On Thursday, France confirmed that a doctor who was in contact with a patient with the new virus later became infected himself. The doctor is now being treated in an isolated room at a Paris hospital. Outbreak specialists worry that the spread of new viruses from patients to health workers can signal the virus is becoming adapted to human transmission.

Russia announced it was closing its 4,185-kilometer (2,600-mile) border with China, joining Mongolia and North Korea in barring crossings to guard against the new viral outbreak. It had been de facto closed because of the Lunar New Year holiday, but Russian authorities said the closure would be extended until March 1.

Meanwhile, the United States and South Korea confirmed their first cases of person-to-person spread of the virus. The man in the U.S. is married to a 60-year-old Chicago woman who got sick from the virus after she returned from a trip to Wuhan, the Chinese city that is the epicenter of the outbreak.

The case in South Korea was a 56-year-old man who had contact with a patient who was diagnosed with the new virus earlier.

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.

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Associated Press writers Maria Cheng in London, Jamey Keaten in Geneva, Edith Lederer at United Nations, Elaine Ganley in Paris, Frank Jordans in Berlin, Mari Yamaguchi in Tokyo and Kim Tong-hyung in Seoul, South Korea, contributed to this report.