BRUSSELS — American tourists who have been fully vaccinated against Covid-19 will be able to visit the European Union over the summer, the head of the bloc’s executive body said in an interview with The New York Times on Sunday, more than a year after shutting down nonessential travel from most countries to limit the spread of the coronavirus.

The fast pace of vaccination in the United States, and advanced talks between authorities there and the European Union over how to make vaccine certificates acceptable as proof of immunity for visitors, will enable the European Commission, the executive branch of the European Union, to recommend a switch in policy that could see trans-Atlantic leisure travel restored.

“The Americans, as far as I can see, use European Medicines Agency-approved vaccines,” Ursula von der Leyen, president of the European Commission, said Sunday in an interview with The Times in Brussels. “This will enable free movement and the travel to the European Union.

Millions of Americans are not getting the second doses of their Covid-19 vaccines, and their ranks are growing.

More than five million people, or nearly 8 percent of those who got a first shot of the Pfizer or Moderna vaccines, have missed their second doses, according to the most recent data from the Centers for Disease Control and Prevention. That is more than double the rate among people who got inoculated in the first several weeks of the nationwide vaccine campaign.