A passenger who landed at Los Angeles International Airport (LAX) from Mexico City was immediately quarantined Wednesday evening after showing possible symptoms of the deadly coronavirus, U.S. health officials announced Thursday.

The traveler arrived at LAX via American Airlines flight 2546 at 6:45 p.m. local time and was swiftly hospitalized by first responders. The Los Angeles Fire Department conducted a “deep contamination process” after the patient was removed from the aircraft, according to Fox 5.

U.S. health officials are reiterating the need to take precautions against the deadly virus, especially due to flu season being underway.

“If you’re sick, if you’re coughing, if you’re sneezing, you need to stay away from other people,” said Dr. Barbara Ferrer, head of the Los Angeles County Department of Public Health.

The development comes as an unidentified Washington State man who recently returned from Wuhan, China — where the illness appears to have originated from — was confirmed to have caught the disease.

Meanwhile, the World Health Organization said Thursday that a viral illness, which has killed 17 people and sickened hundreds, is not yet an international health emergency.

The decision came after Chinese authorities moved to lock down three cities on Thursday and canceled major events in the capital, Beijing, during the Lunar New Year holiday period to try to contain the new virus.

The United Nations health agency announced the decision after independent experts spent two days assessing information about the spread of the newly identified coronavirus.

WHO defines a global emergency as an “extraordinary event” that constitutes a risk to other countries and requires a coordinated international response. Previous global emergencies have been declared for the emergence of Zika virus in the Americas, the swine flu pandemic, and polio.

A declaration of a global emergency typically brings greater money and resources, but may also prompt nervous foreign governments to restrict travel and trade to affected countries. Deciding whether an outbreak amounts to an international crisis therefore can also be politically fraught.

The Associated Press contributed to this report.