PARIS — President Emmanuel Macron of France has tested positive for the coronavirus and will workinisolationforthenext week, promptingotherEuropean leaders he has met to takeprecautionarymeasures and complicating Europe’s efforts to overcome a crippling second wave of the pandemic.

The presidential Élysée Palace announced the illness Thursday without clarifying Macron’s symptoms or the gravity of his condition. As one of Europe’s youngest leaders, at42, thepresidentis not among the most vulnerabletothevirus,butitseffects are known to be unpredictable.

Gabriel Attal, the government spokesman, said:“Late last night, the president began feeling COVID-19- like symptoms. He immediately isolated himself and took a PCR test. The result was communicated to us this morning.” He added that efforts were underway through contact tracing to identify anyone who met recently with Macron.

The Spanish government announced that Prime Minister Pedro Sánchez, who had lunch Monday withMacron, hassuspended his official activities until Dec. 24. In Portugal, Prime Minister António Costa, who lunched Tuesday with Macron, said he would self-isolate and get tested for COVID-19. Charles Michel, a top European Union official, will go into isolation afterameetingMonday with Macron, a spokesman said.

How Macron contracted the virus is a mystery.

Other world leaders who have had it — including President Donald Trump, President Jair Bolsonaro of Brazil and Prime Minister Boris Johnson of Britain — were more cavalier or skeptical about the pandemic.

Macron, however, has been consistent in emphasizing the gravity of the threat, but France has been reticent about revealing details of its president’s health.

Macron, in an apparent attempt to reassure people, made his first public appearance since testing positive, at a planned conference on French development aid late Thursday. Speakingviavideo link and wearing a medical-grade mask, he did not show apparent signs of the sicknessanddidnotmention it in his speech.

The cascade of leaders isolating themselves came at a difficult moment. Europeans across the continent are restive over restrictive measures that have become a tiresome way of life. After six weeks of a second lockdown, an 8 p.m. curfew across France went into effect Tuesday. It will last at least another month.

Macron will celebrate his 43rd birthday in isolation Monday. His wife, Brigitte Macron, who is 67, tested negative for the virus. She is also working in isolation.

The partial disappearance from view of several leaders is likely to sharpen anxiety across a continent facing its most severe recession since World War II.

Millions of people have been furloughed. The French economy, the second-largest in the eurozone, is expected to shrink 9% this year.

Billionsofeuroshavebeen spent to cushion the devastating effect of the virus, but prospects for a quick recovery faded as the number of cases across Europe rose to new heights this fall. The French central bank said Monday that economic activity would not recover to pre-pandemic levels before 2022. Germany, the Netherlands and the Czech Republic are among the countries that have recently imposed lockdowns.

The French weekly Le Point reported that Macron had dined Wednesday night at the Élysée Palace with a dozenofhispoliticalallies, all socially distanced from one another at a long table and wearing masks except when eating. The government has advisedthatnomorethansix peopleshouldgatheraround a table over the holidays. At themeal, Macronshowedno symptoms, participants said.

The president’s approval rating has been hovering around 38%, relatively high for a French leader. It fell as low as 24% in 2018. His tough responses on issues including security, terrorist threats and immigration have reflected the mood of a significant section of a buffeted country.

Whether he would now get a boost out of sympathy for his condition or see concern over a political vacuum affect his popularity was unclear. The next presidential election is 18 months away.

“This may enable Macron to have greater weight and authorityingettingpeopleto observethe lockdown rules,”

Jaques Rupnik, a prominent political scientist, said.

Hopes for better times are vested in a vaccine. Prime Minister Jean Castex, who will also work in isolation after attending the weekly CabinetmeetingWednesday with Macron, announced this week that inoculations would start in the last week of the year.

France is expected to receive a first shipment of 1.16 million doses by then, once European and French authorities have approved the Pfizer-BioNTech vaccine. But the vaccine will be no immediate panacea.

Sincethepandemicbegan, there have been almost 2.5 million confirmed cases of COVID-19 in France and nearly 60,000 deaths, among the worst numbers in Europe.