Five days before a Christmas that many hoped would mark a return to normal, governments across Europe were instead considering new social restrictions and tougher rules to protect their health systems from another potentially devastating coronavirus wave.
In Britain, where new infections driven by the fast-spreading Omicron variant have reached their highest levels of the pandemic, Prime Minister Boris Johnson on Monday described an “extremely difficult” surge of hospitalizations in London and said he was “looking at all kinds of things to keep Omicron under control.”
In Germany, where experts warned that more health workers are testing positive and I.C.U.s and emergency rooms are reaching capacity, government leaders were scheduled to meet on Tuesday to discuss imposing stricter curbs on gatherings before New Year’s Eve.
“We should be careful about ruling anything out,” Hendrik Wüst, the premier of North Rhine-Westphalia, Germany’s most populous state, told the broadcaster ARD, adding: “The big New Year’s Eve parties won’t be able to take place this year.”
The rapid surge of Omicron, less than a month after it was first identified, has confronted European nations with the prospect of a second consecutive Christmas clouded by lockdown-like measures, travel bans and fears of rationed health care. Governments are rapidly accelerating booster shots as the scientific evidence accumulates that two vaccine doses are insufficient to stop infections.
Even though researchers still don’t know whether Omicron causes severe illness in most people, its rapid spread in Britain and Denmark — two countries with high vaccination rates and high levels of disease surveillance — has alarmed the continent.
Researchers in Denmark, where nearly 77 percent of people have had two vaccine doses, found last week that Omicron cases were doubling every two days, and that the variant was mostly infecting people who had been fully vaccinated. The tiny Scandinavian nation is now recording more than 9,000 new cases daily, one of the highest per-person infection rates in the world.
In Britain, the variant has become the dominant strain of the virus in London, where experts say cases are doubling every two days.
In London hospitals, the number of Covid patients rose by 30 percent last week, according to Chris Hopson, the chief of N.H.S. Providers, the membership organization for England’s National Health Service staff. Infections were also cutting into the number of health care providers; staff absences attributed to Covid-19 more than doubled last week, he added, forcing some health facilities to “postpone nonessential activity.”
Concerns over the effect on health systems are part of the reason that the Netherlands over the weekend announced a lockdown, even though the country’s new case totals have fallen from their late November peak, when most cases were of the Delta variant. On Saturday, Prime Minister Mark Rutte ordered the closure of all but essential businesses until the second week of January and limited the number of guests allowed into people’s homes.
Acknowledging that the measures meant “another Christmas that is completely different from what we would like,” Mr. Rutte said that the lockdown was necessary to prevent “an unmanageable situation in hospitals.”
The Netherlands has less I.C.U. capacity than many wealthy European nations, with 6.7 beds per 100,000 people, compared with 19 in France and 14 in the United States, according to the Our World in Data Project at the University of Oxford. Officials say that occupancy rates at hospitals are already high, and experts warn that nurses are being stretched thin.
“The burnout is huge,” said Dr. Mark Seubert, a critical-care physician in the Netherlands. “You see more people leaving the health care sector than joining it.”
Claire Moses, Monika Pronczuk and Jasmina Nielsen contributed reporting.