The French authorities confirmed the first cases of the Omicron version of the coronavirus in mainland France on Thursday, but their alarm remained focused on a surge of infections fueled by the Delta variant.
France reported nearly 50,000 new cases of the virus in 24 hours on Wednesday, the highest daily total since the spring. The number of reported cases per 100,000 people has soared from less than 100 to more than 300 over the past month.
“We need to anticipate — there are still a lot of uncertainties,” Jean-François Delfraissy, the head of the French government’s Covid-19 scientific advisory council, told BFMTV on Thursday, referring to Omicron. “But let’s not fight the wrong fight. The real fight, the real enemy, is the fifth wave with the Delta variant.”
The surge has alarmed French authorities, even though they have so far ruled out a return to lockdowns or business closures. Mr. Delfraissy said that cold had pushed people indoors and that social distancing was no longer being scrupulously followed. The average number of new hospital admissions, including in intensive care, has also increased by roughly 40 percent over the past weeks, according to official statistics.
But hospitalizations are still below the peaks seen in previous waves, thanks to a vaccination rate of 75 percent of the entire population, and Mr. Delfraissy said that if people exercised renewed vigilance — by avoiding gatherings, working from home when possible and wearing masks more often — France could be spared the worst outcomes.
“Christmas isn’t in danger if we are all careful,” he said.
The French government, which recently made all adults eligible for booster shots, has steered clear of mandating vaccines, arguing that coercion would be counterproductive. Olivier Véran, the health minister, told reporters this week that a more “powerful incentive” was the national health pass, which is required to access museums, restaurants, cinemas and other public venues.
The announcement of two Omicron cases on Thursday in mainland France has added to concerns, even though scientists are still trying to understand the threat posed by the variant.
The health authority for the Île-de-France region, which includes Paris, said that the Omicron variant had been found in a man in his 50s, who returned from Nigeria last week and tested positive for Covid-19 after disembarking from his flight, though he showed no symptoms. The man, who was not vaccinated, was isolating at home, officials said.
In eastern France, health authorities in the Grand-Est region said in a statement that Omicron had been detected in a woman in her 40s who returned from South Africa last week. The woman was vaccinated but experiencing symptoms, and has been isolating at home.
Previously, France had confirmed only one case of the Omicron variant, in the overseas department of Réunion, in the Indian Ocean.
Uncertainty over how dangerous Omicron really is had prompted the French authorities to halt flights with 10 countries in southern Africa, where the variant was first detected. Flights will be allowed to resume starting this weekend, but with some restrictions on travelers still in place. France will also require all visitors arriving from outside the European Union to provide a negative coronavirus test result, regardless of their vaccination status.