Travelers to the United States Are Now Required to Test for COVID-19 Within 1 Day

President Joe Biden announced stricter rules for travelers on Thursday — a day after the omicron variant was detected in the United States.

The administration also announced that masks will continue to be required on planes and on public transportation until March 18 — three months after the mandate was set to expire.

When it comes to international travelers or U.S. citizens returning from a trip outside the country, all will be required to test for COVID-19 within one day of departure regardless of their vaccination status.

The new testing requirement will go into effect on Dec. 6.

Previously, vaccinated travelers heading to the U.S. were required to present proof of a negative COVID-19 test three days before arrival, while only unvaccinated travelers were required to comply with the shortened testing window now in place for everyone.

Biden will also move to require insurance to cover the cost of at-home COVID-19 tests, providing a more convenient way to get a test. The president is also setting up family vaccination clinics nationwide that will serve as a one-stop-shop for all doses.

The new protocol comes as the omicron variant emerged in various countries throughout the world and was reported in the United States — in California — on Wednesday.

"A month ago, we announced requirements that travelers must be vaccinated if entering the United States. This week, I announced an additional action to strengthen international travel rules to give us more time to stop the spread and study a new variant," the president said Wednesday.

While the U.S. continues to mandate masks and implements a new testing protocol, the U.K. has added a requirement that international travelers take a COVID-19 PCR test the day after their arrival and self-isolate between landing in the U.K. and receiving negative test results.

After the World Health Organization (WHO) named omicron "a variant of concern" on Friday, dozens of countries including the U.S., U.K., and Canada, responded with new restrictions on travel from more than a half dozen southern African countries within days. Countries including Israel went a step further and closed their borders to all foreign travelers, while Morocco has temporarily suspended all incoming passenger flights.

The WHO has also advised those 60 and older and those with underlying medical conditions to postpone their travel plans.