Chinese officials confirmed Wednesday that 440 patients have now tested positive for the coronavirus that originated in the central city of Wuhan, and that nine people have died—marked increases from the day before.
The news comes as the the illness, which is in the same family as severe acute respiratory syndrome (SARS), spread to the United States on Tuesday, with a Washington State resident testing positive after a trip to China, according to the U.S. Centers for Disease Control and Prevention (CDC).
The virus was first detected as a form of viral pneumonia centered on a seafood market in Wuhan, a city of 11 million people, on Dec. 12. Many of the first reported cases were people who worked at the market, which also sold wild animal meat. Officials closed down the market and identified the illness as a novel coronavirus, named 2019-nCoV.
The largest number of cases are in Wuhan, but it has also spread to over a dozen mainland cities. Cases have also been confirmed in South Korea, Thailand and Japan, Macau and Taiwan—along with the U.S.
The increase in the number of confirmed cases comes just days before the Chinese New Year holiday, raising fears that the virus could spread further as millions across China travel home to visit their families. Some 450 million Chinese were expected to travel across the country and around the world for the holiday. An estimated 7 million Chinese citizens traveled internationally for the holiday in 2019, according to government figures.
The sudden spike in numbers has created fears that this could become a repeat of SARS, which killed nearly 800 people and infected more than 8,000 after beginning in Southern China in 2002. The Chinese government was accused of covering up SARS as it spread through mainland China and into neighboring Hong Kong. Bustling cities emptied as people stayed home to avoid contact with the public, and financial markets were devastated globally.
The patient in the U.S. is a resident of Snohomish County in his 30s, who arrived in Seattle on Jan. 15. He is currently being treated at Providence Regional Medical Center in Everett, Wash.
U.S. public health officials are working to “identify and contact all those who may have come in contact with the infected traveler,” the Washington State Department of Health said in a statement.
Authorities said that the patient is in “good condition” but is hospitalized “out of an abundance of precaution.” They indicated that the “risk to the general public is low,” but noted that enhanced airport screening at some international airports in the U.S. would be one part of a layered public health approach. The man arrived days before federal health officials started such screenings at three major international airports.
Chinese authorities have confirmed that the virus can spread by human-to-human contact and that at least 15 health workers have been infected. In the U.S., the CDC noted that “it’s unclear how easily this virus is spreading between people.”
In response to the outbreak, outbound travelers at Wuhan’s Tianhe International Airport are having their temperatures checked before boarding planes, and those displaying fever symptoms are quarantined.
At the Wuhan Railway Station, employees have been told that they will soon start checking travelers’ temperatures, China Daily reported.
Yuen Kwok-yung, a microbiologist at the University of Hong Kong, called on residents of Hong Kong not to go to Wuhan unless absolutely necessary. “If you really need to, wear a mask and practice good hand hygiene if you go to crowded places or visit a hospital,” he said during a press conference. He also advised those who return back to Hong Kong from Wuhan to wear a mask for 14 days to avoid spreading the virus in case they caught it.
The World Health Organization has scheduled a meeting Wednesday to determine whether to declare the outbreak a “public health emergency of international concern.”
As of Tuesday, Chinese authorities said the virus has been detected in over a dozen Chinese cities outside Wuhan. Among the confirmed cases were 17 patients in four cities—Shenzhen, Zhuhai, Zhanjiang and Huizhou—in the southern province of Guangdong. 10 patients have been diagnosed with the virus in Shenzhen, a port city that borders Hong Kong where there have been 99 suspected cases, though none officially confirmed. Ten cases have been reported in Beijing, and nine in Shanghai.
At least one travel company indicated that North Korea would temporarily close its border to foreign tourists to prevent an outbreak as early as Wednesday.
Chinese President Xi Jinping said Monday the virus would be brought under control. “People’s lives and health should be given top priority and the spread of the outbreak should be resolutely curbed,” state TV quoted Xi as saying.
What do we know about the virus?
Medical experts in China identified the mysterious disease as a novel coronavirus earlier this month. Most coronaviruses result in mild symptoms, including upper-respiratory tract infections like the common cold, according to the U.S. Centers for Disease Control and Protection (CDC). But the classification of the disease puts it in the same family as SARS and the Middle East respiratory syndrome (MERS), both of which killed hundreds.
Chinese health officials had said earlier that there is no evidence of human-to-human transmission of the virus, which has been linked to a seafood market closed for sanitation since Jan. 1. The market also reportedly sold wild animals as game food.
However, late Monday, officials confirmed there had been cases of human-to-human transmission, and health workers had taken ill.
“Surgical mask” is now one of the top trending topics on Chinese social media platform Weibo, with users discussing which kinds of masks are best for preventing infections and others saying that they have ordered boxes of masks.
One user wrote: “I woke up reading about the sharp increase in confirmed cases, so I immediately placed an order of surgical masks on [e-commerce site] Now, the source of the virus has not been confirmed, virus type unclear, transmission path unclear. I’m a little worried.”
Others reported that surgical masks were sold out when they visited local drug stores.
Arnold Monto, a professor in the School of Public Health at the University of Michigan, tells TIME that it may take some time to determine how the disease spreads.
“Something new may have unusual patterns for transmission,” he says.
Read more:The Wuhan Pneumonia Crisis Highlights the Danger in China’s Opaque Way of Doing Things
How serious is the novel coronavirus outbreak?
As of Wednesday, nine people have died in Wuhan and at least 270 in Hubei province, where Wuhan is located, have been diagnosed with the virus.
In the southern province of Guangdong, where 17 patients across four cities are infected with the virus, five are in serious condition and two in critical condition.
Where has the virus spread to outside China?
South Korea confirmed its first case Monday. The 35-year-old Chinese woman arrived in Seoul from Wuhan on Sunday, according to South Korea’s Centers for Disease Control and Prevention.
Thailand and Japan detected cases of the virus last week—authorities in both countries say that patients had visited Wuhan before falling ill.
According to Japanese health authorities, the patient, who is in his thirties, said that he had contact with a pneumonia patient while in Wuhan, but he did not visit the seafood market.
In Thailand, authorities detected a fever in a 61-year-old woman from Wuhan when she landed in the airport in Bangkok and hospitalized her the same day. Last week, Thailand health authorities announced that a second woman from Wuhan, who has been quarantined since she arrived in the country, also had the virus. Thai officials confirmed the patients were in “good critical condition.”
When asked if authorities are considering banning travel from Wuhan to Thailand, Suthat Chotanapan, the director of the Bureau of Risk Communication and Health Behavior Development for the Ministry of Public Health in Thailand, tells TIME in an email that, “We will follow the lead agencies such as WHO or U.S. CDC. At this moment there is still no travel notice that ban for travel to Wuhan. But please be reminded that there is a risk for this virus if you will be there.”
There are 99 unconfirmed cases of the virus in Hong Kong, where high demand for N95 masks made by 3M—which were commonly worn during the SARS outbreak—has caused stock to run out.
Authorities in Vietnam have also placed visitors suspected of having the disease under quarantine.
The first possible case of the virus was reported in Wuhan on Dec. 12, the city’s health bureau says.
What do we know about the first confirmed case of the virus in the U.S.?
The CDC confirmed Tuesday that a male resident of Snohomish County, Wash., who had returned to Seattle’s International Airport on Jan. 15 from a trip to Wuhan, had been infected with the virus.
“This is an evolving situation and we do expect additional cases in the United states and globally.” said Dr. Nancy Messonnier, director of the C.D.C.’s National Center for Immunization and Respiratory Diseases. “There is new information hour by hour, day by day, that we are tracking and following closely,” she added.
The CDC has staff working closely with health officials in China and Thailand, Messonnier said. “The key issue we all need to understand is how easily and sustainably the virus is spread from human to human. We don’t have that completely nailed down yet,” Messonnier said.
After returning from his trip, the man sought out care from a medical provider in Washington, according to state and federal health officials. “This was a very astute gentleman,” said Scott Lindquist, Washington state’s epidemiologist, who noted that the man had researched and shared information about the virus with his provider.
Health care professionals suspected that the man had been infected with the Coronavirus based on his travel history and symptoms and alerted public health officials who later confirmed this was the case.
The CDC said the agency had already been preparing for the introduction of the virus into the U.S. “for weeks” and had told clinicians to be vigilant about patients reporting “respiratory symptoms and a history of travel to Wuhan” as early as Jan. 8.
On Jan. 17, the CDC began implementing public health airport screenings at the San Francisco International Airport, the Los Angeles International Airport and New York’s John F. Kennedy International Airport. This week, these screening procedures will also be used at two more airports — the Hartsfield-Jackson Atlanta International Airport and Chicago O’Hare International Airport.
Officials in Washington State and Snohomish County are also staying vigilant to try and identify those who may have been exposed to the virus through contact with the infected traveler. “As our team of experts partners with infectious disease specialists locally, nationally and around the globe to learn more about the 2019 novel coronavirus, our first priority remains public safety,” said Washington State Secretary of Health John Wiesman. “We believe the risk to the public is low.”
How are authorities responding?
Governments are stepping up precautionary measures in the wake of the outbreak. Hong Kong, Singapore, Malaysia, South Korea and Thailand are also among the places where airport officials are screening passengers arriving from Wuhan.
The U.S. CDC said last week that airports across the U.S. will also screen people traveling from Wuhan for the virus, including at JFK International Airport, San Francisco International Airport and Los Angeles International Airport. The U.S. embassy issued a low-level alert for travel to Wuhan earlier this month.
On Tuesday, authorities in Australia announced that though the risk to Australians is low, that precaution will be taken at the Sydney airport where three direct flights from Wuhan arrive each week. All passengers coming from Wuhan will be screened and asked if they are experiencing symptoms such as fever, cough, breathlessness and sore throat.
The World Health Organization (WHO) says it is proposing studies on the coronavirus “to better understand transmission, risk factors, and where the virus is.”
Chinese authorities were criticized for trying to cover up the SARS epidemic, which started in southern China, but experts say they have learned from their mistakes.
“I think the public health authorities in China realized that that really was not the way to handle things, that things come out eventually, that response is best when it is handled promptly,” Monto, the University of Michigan public health professor, says.
While a number of cases have now been confirmed in other Chinese cities, little still is known about the novel disease. Experts say this may be due to ongoing development of testing for the new form of coronavirus.
“In the recognition of any new disease, there’s a problem in trying to be sure you’re identifying that particular disease when you don’t really have the diagnostic test,” Monto says. “When it’s a novel agent, developing a quick test takes awhile.”
Could this evolve into a large-scale outbreak like SARS?
Experts say the rapid developments of the past few days are worrying, but also point out that Chinese authorities are responding much more quickly to the virus this time than they did to SARS in 2003.
“They closed the seafood market on Jan. 7, shared the genome sequence on Jan. 10 and passed it onto WHO on Jan. 12,” David Hui, a respiratory medicine expert at the Chinese University of Hong Kong, says. “In terms of lab investigation, they have been highly efficient.”
According to Hui, the virulence of the disease appears to be on the low side. “I think the chances of the virus developing into an international outbreak is not very high,” he says, but adds that authorities need to locate the source of the virus as soon as possible to prevent a further spread.
“The sooner they find it, the easier it would be to control the outbreak,” he says.
Still, professor Gabriel Leung, the dean of the University of Hong Kong’s Faculty of Medicine, said at a press conference Tuesday: “[There is] a very strong sense of deja vu [with SARS], except the time scale has been compressed.”
He added: “Whereas you saw an unrecognized epidemic brewing for months since the end of 2002 up until the peak of it in March and April in Hong Kong, here you are talking about the same number, but the unit is weeks.”
Statistics modelling led by Leung suggests that there could be over 1,300 cases in Wuhan, in line with research by the London-based team that states the number of patients infected with the virus is significantly more than is being reported. Leung also says there could be one or two cases in Hong Kong, but insufficient data makes it difficult to make credible predictions.
How can you protect yourself?
As the number of cases continue to rise, health authorities are calling on the public to exercise increased caution. Wuhan’s health bureau has advised residents to seek medical attention immediately if they experience symptoms including fever or cough.
Public health officials in Hong Kong said residents should wear masks if they don’t feel well, or when visiting hospitals.
The Hong Kong Center for Health Protection also advised against contact with live animals or game meat.
Leo Poon, a virologist and SARS expert at the University of Hong Kong, says it is best to avoid densely populated areas and maintain good personal hygiene, especially frequent hand washing.
But too little is known about the virus to give any definitive advice, he adds, such as whether citizens should wear a face mask in public places.
“We don’t know how efficient human-to-human transmission is, if it is caused for example by close contact or droplet transmission,” he says. We definitely need an answer for that. Without it, it’s hard to come up with practical preventive measures.”
— Aria Chen in Hong Kong and Madeleine Carlisle in New York contributed to this report
Write to Hillary Leung at and Amy Gunia at