The requirement would come as part of the administration's phased approach to easing travel restrictions for foreign citizens to the country. No timeline has yet been determined, as interagency working groups study how and when to safely move toward resuming normal travel. Eventually all foreign citizens entering the country, with some limited exceptions, are expected to need to be vaccinated against COVID-19 to enter the U.S.

The official spoke on the condition of anonymity to preview the policy under development.

The Biden administration has kept in place travel restrictions that have severely curtailed international trips to the U.S., citing the spread of the delta variant of the virus. Under the rules, non-U.S. residents who have been to China, the European Schengen area, the United Kingdom, Ireland, Brazil, South Africa and India in the prior 14 days are prohibited from entering the U.S.