The U.S. government is expected to require all international airline passengers to show proof of a negative Covid-19 test before boarding flights to the country, people familiar with the matter said.

The U.S. Centers for Disease Control and Prevention is planning to issue its order as soon as Tuesday, following weeks of discussions among federal agencies and the White House coronavirus task force. The order is expected to go into effect Jan. 26, according to a person familiar with the matter. The CDC and other administration officials were still finalizing the order.

The CDC order for universal testing, including for U.S. citizens returning from abroad, requirement comes weeks after the Trump administration on Dec. 24 implemented a testing requirement for travelers from the U.K. amid rising concerns over a more infectious strain of the new coronavirus originally detected there. Since then, the new strain has been found elsewhere in the world, and its presence in the U.S. has been confirmed.

The U.S. requirement comes during a difficult time for the aviation industry and international travelers who face a thicket of varied testing protocols and quarantine requirements around the world, including public health advisories urging people to stay home to help limit the virus’ spread.

U.S. airlines have voiced support for the new requirement, but have argued that ramped-up testing protocols should take the place of travel restrictions and quarantines to reduce the spread of Covid-19.