With case numbers having increased by more than 600% in the past week, the Mediterranean archipelago has become the first country in the European Union to announce a ban on visitors who are not themselves fully vaccinated, or who are not under-12s brandishing a negative PCR test while accompanying vaccinated parents.

The ban will take effect on Wednesday, with an exemption for Maltese citizens and residents who have already booked a flight home; they will still be able to enter with a negative PCR test.

“In recent days, the majority of new cases were related to travel—people who came from abroad or Maltese who went abroad and came back. Most are those unvaccinated tourists,” said Health Minister Chris Fearne on Friday. He added that many cases have been coming from English schools, which the government will also be temporarily shuttering.

It’s a significant and speedy U-turn for a country that made a big deal of reopening to both vaccinated and unvaccinated tourists at the start of last month, and that was running advertorials as recently as last week, boasting that “no quarantine or other restrictions apply for fully vaccinated tourists coming to Malta or those presenting a PCR COVID-19 test taken not earlier than 72 hours before arrival.”

Less than a month ago, Malta said people from 38 U.S. states could visit the country with a negative PCR test. That’s now over. Even if American tourists can prove they are vaccinated, Malta accepts only vaccine certificates issued in the EU or the U.K.

Most worryingly for the travel industry and for the European Commission, the EU’s executive body, what Malta just did flies in the face of the united stance on border restrictions and “vaccine passports” that has just been adopted across the union.

Since the start of July, there has been a common framework for EU countries accepting digital COVID certificates at their borders. The certificates indicate if a person has been vaccinated, has a recent negative PCR test result, or has recovered from COVID-19. Malta, which has already been ignoring the last option for months, is now effectively accepting only one of three criteria underpinning a system that’s less than two weeks old.

The Commission, which has spent the pandemic desperately trying to retain some semblance of the EU’s fundamental free-movement arrangement, is not amused.

“Any [public health measure] that restricts free movement needs to be proportionate and nondiscriminatory,” said Commission spokesman Christian Wigand at a Monday press conference. “A vaccine certificate cannot be a precondition for the exercise of free movement. This is one of the main principles of the EU digital COVID certificate regulation.”

Maltese Prime Minister Robert Abela had already said in a Sunday radio interview that the European Commission was critical of the measure. “We were already more restrictive than the others, and now we will be even more restrictive…The lives and livelihoods of the Maltese are what matters,” he said.

The Association of British Travel Agents told the Guardian that Malta’s new rules were “confusing” but said it was confident other EU countries would remain open to travel—even those such as Spain, which is also seeing a vertiginous rise in case numbers.