United Airlines on Tuesday said it is canceling dozens of China flights next month because of a "significant decline in demand" for service to the country as it battles the growing number of coronavirus cases.

The Centers for Disease Control and Prevention on Tuesday recommended travelers avoid all nonessential travel to China while the Trump administration announced plans to expand screenings for the virus from five to 20 U.S. airports.

United has the most service to China among U.S. airlines.

The flight cancellations take effect Feb. 1 and last through Feb. 8. United also expanded it's travel waiver to include Hong Kong on Tuesday evening.

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It wasn't immediately clear if United would cancel more flights.

"We will continue to monitor the situation as it develops and will adjust our schedule as needed," United said in a statement. The airline operates about 12 flights a day from the U.S. to mainland China and Hong Kong, and the changes will cut that number by three or four per day. United will reduce service to Hong Kong from San Francisco and Newark, New Jersey; to Beijing from Washington Dulles, Newark and Chicago; and Shanghai service from San Francisco, Newark and Chicago.

Air Canada said Tuesday that it was also canceling some China flights "to better match capacity with expected demand." The carrier said it has 33 flights to China a week "and the resulting capacity reduction is relatively small." Customers affected by the cancellations can change their travel plans with the airline

American Airlines and Delta have not cut their China flights, but all three carriers are waiving change and cancellation fees for travelers booked to China because of the virus.

U.S. health officials said that the immediate risk from the virus that has infected roughly 4,700 people across the globe and killed 106 in China was low for Americans, but U.S. Health and Human Services Secretary Alex Azar warned Tuesday that it was still a "potentially very serious public health threat."