The U.S. is developing a plan to require nearly all foreign visitors to the nation to be fully vaccinated against COVID-19 as part of eventually lifting travel restrictions that bar much of the world, a White House official said on Wednesday.

The administration of U.S. President Joe Biden wants to reopen travel, which would boost business for the airline and tourism sectors, but is not ready to immediately lift restrictions because of the rising COVID-19 caseload and highly transmissible COVID-19 delta variant, the official said.

The Biden administration has interagency officials working "to have a new system ready for when we can reopen travel," the official said, adding that it includes "a phased approach that over time will mean, with limited exceptions, that foreign nationals traveling to the United States (from all countries) need to be fully vaccinated."