It's unclear whether the passenger who arrived at Los Angeles International Airport has contracted the flu-like virus or what their symptoms included, according to reports.
The passenger was quarantined on Wednesday night after arriving into the US on an American Airlines flight. They were intercepted by police and firefighters and brought to a local hospital.
Recent tests have cleared a patient that Mexican authorities reported was under observation as a potential case for the severe respiratory illness.
LAX is among three US airports that began screening passengers entering the US from Wuhan, China, where more than a dozen deaths have been reported and thousands of others may have been infected. As of Thursday, three cities in that region are on lock-down as officials scramble to contain the outbreak.
On Tuesday, the first travel-related case in the US was reported in Washington state.
At least 16 people are under medical surveillance after coming in contact with a man in his 30s in Everett, Washington. The state's medical chief says the patient appears to be in good condition and that none of the people who were in close contact with the patient are exhibiting any symptoms.
The patient is a US resident who travelled to the region but not visit the meat and fish markets where authorities believe are a source of the outbreak. He was screened on 17 January.
The latest potential US case arrives on the heels of a warning from Los Angeles Department of Public Health officials that the county could see a possible coronavirus patient as the area sees an increase in travellers from China amid Lunar New Year celebrations.
This week, Donald Trump said the virus is "completely under control" in the US and limited only to "one patient".
On Saturday, the Centers for Disease Control and Prevention announced that LAX as well as San Francisco International Airport and John F Kennedy International Airport in New York would be supported by additional medical staff to to screen sick passengers and assist with possible quarantines.
This week, the CDC will add additional screenings at Atlanta Hartsfield-Jackson and Chicago O'Hare airports. The health agency also raised its travel warning to alert passengers to "practice enhanced protections".
As of Tuesday, airports have screened more than 1,200 passengers.
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