The U.S. government will require all international airline passengers to show proof of a negative Covid-19 test before boarding flights to the country, the Centers for Disease Control and Prevention said Tuesday. The CDC’s order, confirming earlier reporting by The Wall Street Journal, followed weeks of discussions among federal agencies and the White House coronavirus task force. The order will go into effect Jan. 26.

CDC Director Robert R. Redfield said in a statement that testing doesn’t eliminate all risk, but can make travel safer when combined with other precautions such as wearing masks.

The CDC order for universal testing of passengers, including U.S. citizens returning from abroad, comes weeks after the Trump administration imposed a testing requirement for travelers from the U.K. over concerns about a more infectious strain of the virus that was detected there. Since then, the new strain has been found elsewhere in the world, and its presence in the U.S. has been confirmed.

Travelers arriving on international flights to the U.S. will need to get tested within three days of flying, and airlines will be required to deny boarding to anyone without documentation of a negative test, the CDC said. The order exempts airline crew, along with military personnel and passengers under 2 years old.

Dr. Martin Cetron, who leads the CDC’s Division of Global Migration and Quarantine, said the change was necessary in light of postholiday surges in Covid-19 cases and the larger number of international travelers arriving in the U.S. each day. International air traffic is still down dramatically from last year, but the number of arriving passengers has risen sixfold from June to November, according to figures from the Bureau of Transportation Statistics.

“If people are going to ignore the strong admonishments not to travel, we have to make that travel experience as safe and healthy and responsible as possible,” Dr. Cetron said in an interview.