French cinemas, museums and sports venues have begun asking visitors to furnish proof of Covid-19 vaccination or a negative test as the country, which is in the throes of a fourth wave of infections, rolled out a controversial vaccine passport system.
The so-called "health pass" is required for all events or places with more than 50 people, before being extended to restaurants, cafes and shopping centres in August.
Prime Minister Jean Castex defended the strategy, noting that 96% of the 18,000 new daily cases reported today - an unprecedented surge of 140% in just a week - were people who had not been immunised against the virus.
"We're in the fourth wave," he told French media, stressing that the goal of the health pass was to avoid a fourth nationwide lockdown.
Around 56% of the French population has received at least one dose of a Covid-19 vaccine, with 46% having had both, according to data by the covidtracker.fr website.
The Louvre was among the venues that began implementing the checks, with officials saying that foreign tourists were unperturbed at being asked to show proof of vaccination or a negative test, having already done so when entering the country.
Across the Seine river, at the Eiffel Tower, visitors who turned up without proof of vaccination were being offered tests.
But some people were wrong-footed by the new rules.
In the Paris suburb of Rosny-sous-Bois, 28-year-old Marie-Ange Rodrigues was surprised to be barred from a cinema screening after having just received her second vaccine shot.
"It's rubbish!" she said of the requirement to have been fully vaccinated for at least a week.
Tens of thousands of vaccine sceptics took to the streets in protest over the measures last week, accusing President Emmanuel Macron of running a vaccine "dictatorship".
The restrictions have also faced criticism from politicians in Mr Macron's Republic on the Move (LREM) party, who see it as a threat to civil liberties.
"Protecting public health has been our priority since March 2020, but it has not threatened the cohesion of our country because the rules were the same for everyone," LREM politician Pacome Rupin said. "The health pass is going to fracture our country," he said.
Restaurant owners in particular are up in arms at the requirement to vet their customers' vaccination status before serving them.
In a concession last Thursday, Mr Castex said that they would not have to check customers' ID and that the government would not punish venues during the first week of the new rules.
After that, they face fines of up to €1,500 for a first-time offence and more for subsequent violations.
Children aged 12 to 17, who only became eligible for vaccination in mid-June, will not need the pass in August and will not have to show one when heading back to school in September.
The changes introduced today were implemented by decree, but politicians are set to vote on legislation that will extend the system next month to restaurants, as well as trains or planes for long-distance travel.
From September, vaccinations will also be mandatory for healthcare and retirement home workers, many of whom have been wary or dismissive of the shots.
With admissions to intensive care units low but trending upwards, the head of the Paris public hospital network, Martin Hirsch, warned that the fourth wave could be as big as the previous editions.
Other measures to contain the surge in new cases include the reintroduction of rules requiring masks to be worn outdoors in hotspots such as the western coastal area around Bordeaux, a popular holiday destination.