The Biden White House on Monday unveiled stricter vaccine and testing rules for international travelers, including U.S. citizens.

The new policy goes into effect November 8, requiring unvaccinated U.S. citizens, as well as green card holders, to abide by stricter testing requirements when coming back into the United States. Under the new rules, they will have to show a negative test within a day of their flight. Vaccinated U.S. travelers, however, can work on a 72 hour timeline “as long as they share contact tracing information,” according to Bloomberg, which noted that unvaccinated foreigners “will be generally barred from entry”:

The new policy will place further strain on airlines, which will be tasked with verifying vaccination records and enforcing the new rules:

Under the policy, those who are unvaccinated will need to show proof of a negative COVID-19 test within a day of travel, while those who are vaccinated will be allowed to present a test taken within three days of travel.

Children under 18 will not be required to be fully vaccinated, given the inconsistency in the global roll-out of shots for their age cohort, but those aged 2 and over will be subjected to the same COVID-19 testing policy as their parent or guardian.

Last month, the Biden White House announced it would require most foreigners traveling to the U.S. to be fully vaccinated and provide proof of a negative test in order to enter the country.