BRUSSELS — The European Union is recommending that its 27 member countries reinstate restrictions on American travelers, a change that would primarily affect unvaccinated people, as soaring rates of new coronavirus infections have made the United States a global pandemic hot spot.

E.U. officials decided Monday to remove the United States from the bloc’s “safe list” of countries whose residents should not face travel restrictions. But the move comes with several caveats: The recommendation is not legally binding, and it is up to individual members to decide whether to implement it.

Officials maintained that if European countries accept proof of vaccination, they should continue to admit inoculated travelers, regardless of where they are from, as long as they have received a full regimen of an approved vaccine.

Restrictions “can vary from state to state, but it is widely expected that fully vaccinated Americans would still maintain unfettered access” to the European Union, said an E.U. diplomat who spoke on the condition of anonymity to discuss internal deliberations.

The proposal comes after weeks of deliberation and amid an ever-worsening outbreak in the United States. The E.U. first lifted restrictions on American travelers in June, a decision that reflected an improving epidemiological picture, and reopened borders at the height of summer, when hard-hit southern European economies were desperate for an influx of tourism spending.

The hyper-transmissible delta variant of the coronavirus has left would-be travelers uncertain. The Post spoke to an expert about how to safely make that call. (The Washington Post)

But much has changed since then. Vaccination levels in many European countries have surpassed those in the United States, and the hyper-contagious delta variant has fueled a fourth wave of infections.

“The United States got a free pass over the summer, even as the situation in many parts of the country deteriorated dramatically,” said Jacob Kirkegaard, a senior fellow at the German Marshall Fund who has been tracking travel policies.

According to the bloc’s official recommendations, countries should not be on the “safe list” if they have reported more than 75 new coronavirus cases per 100,000 residents over the past 14 days. The United States was already clocking close to 400 new cases per 100,000 people on Aug. 10.

But the E.U. held off on endorsing restrictions and instead signaled that it was “monitoring the epidemiological situation in countries where the covid situation has deteriorated,” including the United States.

Nearly three weeks later, things have only gotten worse: The United States has reported more than 620 new cases per 100,000 people — more than eight times the E.U. threshold — according to a Washington Post tally.

With summer ending and fears that colder weather will bring increased spread, E.U. officials decided they could no longer tolerate the high level of new cases in the United States.

It’s the latest chapter in the ongoing travel-restrictions saga that has been a source of increasing transatlantic tension. Even as Europe made allowances for American travelers, the United States refused to reciprocate.

Most European travelers have been barred from the United States since the start of the pandemic. President Donald Trump lifted the rules near the end of his term, but President Biden quickly reinstated them after taking office. Critics have said the ban — which is far stricter than the E.U. policy — is hurting business and keeping families divided.

“The U.S. exceptions became harder and harder to defend in the face of a lack of reciprocity from the Biden administration,” Kirkegaard said.

European leaders had repeatedly called for such reciprocity, and they hinted that they would push for tighter rules if the United States continued to keep its doors shut. Even as the E.U. announced the new recommendation, one of the bloc’s top commissioners was in Washington and discussed the issue with Homeland Security Secretary Alejandro Mayorkas.

“It’s something that we follow, of course, very closely,” said Adalbert Jahnz, a spokesman for the European Commission, the E.U.'s executive branch.

The E.U. recommendation set an important precedent because borders are open between member states and there is an interest in maintaining a united stance.

But because the bloc’s guidance is not mandatory, countries have diverged from it in recent months. Greece, for example, opened to U.S. tourists in April, earlier than its neighbors. And in mid-August, Germany added the United States to its list of “high-risk areas,” meaning that unvaccinated travelers would need to quarantine or be tested upon arrival.

It was not immediately clear which countries would enact the new rules. Some governments could decide to admit the unvaccinated only after quarantining or testing; others could go further than the E.U. and subject even the vaccinated to those measures.

Kirkegaard said that it’s unlikely that this will change the experience of most vaccinated Americans traveling to Europe, and that countries with large economic incentives — such as Greece, Italy and Spain — are the most likely candidates to ignore the rules altogether. The bigger question, he added, will be how governments continue to verify travelers’ vaccination status.

In most cases, vaccination cards from the Centers for Disease Control and Prevention should suffice, experts said, but negotiations for a joint E.U.-U.S. digital vaccination passport are still ongoing.

The new E.U. guidance also removes from the “safe list” Israel, Kosovo, Lebanon, Montenegro and North Macedonia.

Trade groups criticized the E.U. advice, saying it represents a significant step backward and would continue to hurt economies.

Airlines for Europe, the largest E.U. airline association, urged policymakers to rethink the decision, arguing that the rampant community spread on both sides of the Atlantic shows that air travel is not fueling new virus cases. The restrictions, the group said in a Monday statement, are “extremely disappointing for Europe’s airlines and our ailing tourism sector."

Quentin Ariès contributed to this report.