European summer vacations are back for Americans, but they’re far from carefree.

Weeks after popular destinations like Greece, France and Spain reopened to U.S. travelers, they are putting new restrictions into place amid a rise in coronavirus cases. In some cases, those measures will limit the venues where unvaccinated visitors can go.

“Many of the European summer hot spots are working to implement societal restrictions that will still allow for [tourists] to conduct regular recreation,” said Jeremy Prout, director of security solutions at health and security services firm International SOS, in an email. “Basically, they’re trying to save their summer, as safely as possible.”

In Greece, which was early to welcome tourists back in May, officials said last week that public indoor spaces would only be accessible to fully vaccinated people through at least Aug. 31.

French President Emmanuel Macron said last week that unvaccinated people who want to dine indoors, go to shopping malls or cinemas, or take planes or trains, would need to show proof of a recent negative coronavirus test or infection and recovery. He said the steps were an effort to “put restrictions on the unvaccinated rather than on everyone.”

On Wednesday, the Associated Press reported that tourists waiting to ride up the Eiffel Tower had to get coronavirus tests on-site if they didn’t have proof of vaccination, a recent negative test or immunity through infection.

Some regions in Spain have restored overnight curfews and limits on social gatherings, among other activities, Reuters said. And in Malta, those without certification of vaccination will be subject to quarantine, the Associated Press reported last week. Authorities on the island initially wanted to only allow vaccinated travelers, but changed course.

The rising cases and shifting rules are a reminder of the unpredictability of the virus, even more than a year into the pandemic. The Centers for Disease Control and Prevention tells people not to travel internationally until they are fully vaccinated.

Prout said he would expect to see more destinations close to international visitors or institute more restrictive entry rules — such as longer quarantines and more tests — if countries struggle with infections, especially as highly contagious variants emerge.

“International travelers need to expect change and keep up to date with it,” he said in an email. “Because of the spike in cases worldwide, restrictions and requirements can change at the drop of a dime prior to your travel or even while at your destination.”

Prout recommended that travelers communicate with their airline before traveling so they are aware of any restrictions; check the CDC’s covid-19 travel recommendations by destination and go to the State Department’s travel advisory site, which includes links to covid-specific information.

“Deciding whether to take an international trip is going to very much be an individual decision that needs to factor in personal health, destination restrictions and your ability to endure some stressors throughout the journey,” he said.

The European Travel Commission said in a statement that vaccination programs have made it possible to travel safely again, but urged greater international cooperation to establish more consistent travel rules.

“We all — destinations, businesses and guests — cannot let our guard down too soon both for our own health and for the safety of people around us,” the statement said. “We won’t get back to ‘normal’ straight away, but to boost confidence in Europe as a destination, it would be helpful to have consistency of rules.”

Staff writers Erin Cunningham and Rick Noack contributed to this report.