The US has reported its first case of a new and potentially deadly virus circulating in China.
The man in his 30s had returned last week from the outbreak's epicentre in Wuhan City, China.
US Health officials say the man, a Washington State resident, was not considered a threat to medical staff or the public and has been taken to hospital in a good condition.
Coronavirus has so far infected about 300 people, all of whom had been in China, and killed six.
The newly discovered virus can cause coughing, fever, breathing difficulty and pneumonia.
Since the outbreak, first identified on December 31 last year, airports in the US and other countries have stepped up monitoring, checking passengers from China for signs of illness.
The US is the fifth country to report seeing the illness, following China, Thailand, Japan, and South Korea.
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Late last week US health officials began screening passengers from the affected Hubei Province in central China, with checks in place at New York City’s Kennedy airport and the Los Angeles and San Francisco airports.
On Tuesday, the Centres for Disease Control and Prevention (CDC) announced it will plans to add screening checks at Chicago’s O’Hare airport and Atlanta’s airport too.
Officials will also begin forcing all passengers that originate in Wuhan to go to one of those five airports if they wish to enter the US.
Officials around the world have implemented similar airport screenings in hopes of containing the virus during the busy Lunar New Year travel season.
Last month, doctors began seeing the new virus in people who got sick after spending time at a food market in Wuhan.
More than 275 cases of the newly identified coronavirus have been confirmed in China, most of them in Wuhan, according to the World Health Organisation.
The count includes six deaths - all in China, most of them age 60 or older, including at least some who had a previous medical condition.
Older patients with an underlying disease who might contract the viral pneumonia are more likely to progress to severe disease.
Officials initially said coronavirus will probably spread from animals to people, but this week Chinese officials said they have concluded it can also spread from person to person.
Health authorities this month identified the germ behind the outbreak as a new type of coronavirus.
Sars, or severe acute respiratory syndrome, belongs to the coronavirus family, but Chinese state media say the illness in Wuhan is different from coronaviruses that have been identified in the past.
Health authorities are keen to avoid a repeat of severe acute respiratory syndrome (SARS), which started in southern China in late 2002 and spread to more than two dozen countries, killing nearly 800 people.
- ITV News Asia Correspondent Debi Edward in Beijing on why the confirmation of a coronavirus case in the US is a blow for Chinese authorities attempts to contain the virus
The new virus so far does not appear to be as deadly as Sars and Mers, but viruses can sometimes mutate to become more dangerous.
University of Washington coronavirus researcher David Veesler said the public "should not be panicking right now".
The response has been "very efficient," he said. "In a couple of weeks, China was able to identify the virus, isolate it, sequence it and share that information."
He added: "We don’t have enough data to judge how severe the disease is."
The CDC’s Dr Nancy Messonnier said health officials expected to see more cases in the US and around the world in the coming days.