(Bloomberg) -- The Biden administration plans to tighten travel rules to combat the omicron variant of the coronavirus, by requiring all air travelers to the U.S. to be tested within a day of their departure regardless of vaccination status, according to a person familiar with the matter.

President Joe Biden plans to announce the new requirements on Thursday in a speech detailing his plan to contain the pandemic through the winter. Currently, vaccinated travelers must get tested within three days of boarding their flight to the U.S.; under the change, that would be cut to one day.

The U.S. last week imposed travel restrictions that bar arrivals from foreign nationals who have been in any of eight southern African nations in the past 14 days. The administration hasn’t said how long those measures will be in place.

The Washington Post earlier reported the administration’s plans for tightening travel restrictions.

A spokeswoman for United Airlines Holdings Inc. said the company could not comment on any policy without first seeing it. A representative for American Airlines Group Inc. declined to comment.

The administration isn’t considering tightening rules on what type of test is required for entry to the U.S. The administration has only imposed requirements for rapid antigen tests, which may be less effective at detecting cases of the omicron variant.

Earlier Tuesday, the Centers for Disease Control and Prevention director, Rochelle Walensky, said the agency was looking into measures such as narrowing the testing window for travelers into the country and adding quarantine requirements in certain cases. The CDC, she added in a call with reporters, was also expanding surveillance programs at four major airports to test for Covid from specific international arrivals.

“As we have done throughout the pandemic, CDC is evaluating how to make international travel as safe as possible,” she said on the call. 

Asked Tuesday evening how long the most recent curbs would remain in place, Biden said, “Well, it depends. It’s going week to week to determine what the need and what the state of affairs is. We’re going to learn a lot more in the next couple of weeks” about the omicron variant.

(Updates with Walensky quote, in eighth paragraph. An earlier version corrected misspelling of omicron in headline and article.)

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