The easing of travel restrictions, imposed 18 months ago by Donald Trump as the Covid-19 pandemic first erupted, marks a significant shift by Biden and answers a major demand from European allies at a time of strained diplomatic relations.
Numerous safeguards will remain in place to suppress the spread of the virus, which has already killed more than 670,000 Americans and is resurgent after what many had hoped was a lasting dip earlier this year.
"Most importantly, foreign nationals flying to the US will be required to be fully vaccinated," Zients said.
It wasn't immediately clear if the new rule only applied to US-approved vaccines or if other brands, such as those produced in China or Russia would also qualify. Zients said that would be determined by the US Centers for Disease Control.
Restrictions on vehicle movement from Canada and Mexico will remain in place. "We do not have any updates on the land border policies," Zients said.
Zients said passengers will need to show they were fully vaccinated before boarding planes to the United States, as well as providing proof of a negative Covid-19 test taken within three days.
Americans not fully vaccinated will still be able to enter but only on testing negative within a day of travel.
Masks will be obligatory on US-bound flights and airlines will provide the US health authorities with contact tracing information.
"This new international travel system follows the science to keep Americans' international air travel safe," Zients said.