BRUSSELS — The massive spike in COVID-19 cases in recent weeks is threatening the European Union’s recovery from the deep economic slump caused by last year’s onset of the pandemic, the bloc’s economy chief said Wednesday.

And medical experts warned that the public health situation could get much worse.

Only two weeks ago the EU executive raised its growth forecast for an economy bouncing back from the worst of the pandemic. But EU Economy Commissioner Paolo Gentiloni said Wednesday the upbeat picture was now in doubt again amid rising infections and with restrictions being reintroduced in a growing number of member states.

The fear is that the fall forecast for 5% growth this year in the 19-nation eurozone could still be hurt by the end-of-year virus crisis.

“Our only message is: Take the situation very seriously,” Gentiloni said, “but without thinking that the economic impact will be the same one as one year ago.”

Medical experts warned of more hardship ahead, and called for urgent measures that could impact crucial sectors like the restaurant, bar and tourism industries, already badly hit by the virus last year.

The European Center for Disease Prevention and Control said in a report Wednesday that the burden from the highly contagious delta variant first detected in India “is expected to be very high in December and January,” unless drastic government action in taken and vaccinations tick further upward.

It all goes against initial expectations for the holiday season when it was thought that Europeans unburdened by COVID-19 restrictions would dip into their forced savings of the past year and spend, giving the economy a major shot in the arm.

Now, the ECDC warned, “the end-of-year festive season is traditionally associated with activities such as social gatherings, shopping and travelling, which pose significant additional risks for intensified transmission of Delta.”

ECDC Director Andrea Ammon spoke of health systems already being overwhelmed in some EU nations, and others being close to it. “We have to take it now really serious in the sense that measures have to be applied in order to reduce transmission.”

In the past though, this has meant lockdowns and wholesale closures of businesses that were responsible for the unprecedented economic slump.

Ammon was addressing everything from less intrusive measures such as mandatory mask wearing or remote work to lockdowns.

“We still have some time until Christmas,” Ammon said. “But if the situation doesn’t get better, it might mean that these measures should be taken over Christmas as well.”