Emmanuel Macron is in a "stable condition", his doctor said in a statement two days after the French President tested positive for COVID-19.
The French leader still presents symptoms of the virus, including fatigue, cough and body aches, the statement said, but those are not stopping him from fulfilling his duties.
Clinical examinations are carried out on a regular basis and results are "reassuring", said Jean-Christophe Perrochon, Chief Doctor of the French Presidency.
The French president is currently quarantining at La Lanterne, an official residence in Versailles, where he will stay for seven days and work remotely.
His officials have declined to comment on any treatment he is receiving.
Several leading political figures at home and abroad have also begun self-isolating, after recently coming into contact with Macron. They include French Prime Minister Jean Castex.
Le Figaro reports that it was told by Macron's entourage earlier this week that the president had been tested several times since the start of the pandemic, with negative results each time until now.
His recent meetings included a visit by Portuguese Prime Minister Antonio Costa to Paris on Wednesday, while a week ago Macron was in Brussels for a European Council summit of EU leaders.
Macron 'contact cases' self-isolate
The news of the French president's diagnosis was quickly followed by announcements that other politicians, who have recently come into contact with Macron, are to self-isolate.
They include European Council President Charles Michel and Spanish Prime Minister Pedro Sanchez. AFP reports that Sanchez has placed himself into quarantine until December 31.
Michel's spokesman Barend Leyts said the council president met Macron in Paris on Monday.
Ursula von der Leyen tested negative on Monday and has no plans to self-isolate, an EU spokesperson said. The European Commission president tweeted her support for Macron, wishing him a speedy recovery.
Attention has focused on last week's European summit on December 11, which Macron and other EU leaders attended in Brussels.
"All sanitary measures were observed and we have not been informed of any other participant or staff present during the last week’s summit who tested positive," an EU official told Euronews.
In France, Prime Minister Jean Castex is self-isolating but has tested negative for coronavirus on Thursday, his Matignon office said.
It announced the test earlier, adding that he was not displaying any symptoms. Health Minister Olivier Véran is reportedly standing in for Castex in parliament.
The President of the National Assembly Richard Ferrand will also self-isolate for seven days as a "contact case" following President Macron's positive test, said a statement from the French parliament. Several other parliamentary figures are reported to be doing the same or to have cancelled meetings.
Brigitte Macron, the president's wife, is also self-isolating but "is displaying no symptoms", her office announced. She had tested negative for COVID-19 as recently as Tuesday before visiting a Paris hospital, AFP reports.
A planned visit by Emmanuel Macron to Lebanon next week has been cancelled, the Elysée has said. The president was due to spend time with French military personnel serving with the UN force in the country, and to meet senior Lebanese leaders.
France's COVID struggle
The news of the French president's positive test result comes as France, like many European countries, is struggling to keep new coronavirus cases under control.
This week the prime minister announced plans for a mass vaccination programme to begin by the end of this month, subject to approval by the European Medicines Agency and the French regulator.
On Wednesday France exited a month-and-a-half long lockdown but now has an overnight curfew from 20.00 to 06.00 to curb the spread of COVID-19.
In a tweet, British Prime Minister Boris Johnson said he was sorry to hear the news and wished Macron a speedy recovery. He also tweeted the same message in French.
Johnson is one of several world leaders to have tested positive for the coronavirus this year. Others include US President Donald Trump and Brazilian President Jair Bolsonaro.