France could "at any moment" lose control over the spread of the coronavirus, the government's COVID-19 scientific council warned Tuesday as official data showed the first rise in intensive care patients since April.
In an opinion prepared for policy-makers, the council warned "the virus has recently been circulating more actively, with an increased loss of distancing and barrier measures" since France emerged from a strict two-month lockdown in May.
"The balance is fragile and we can change course at any time to a less controlled scenario like in Spain, for example," it said.
And the council warned of a possible "resumption of circulation of the virus at a high level" by autumn 2020, after the August summer holidays.
In the short term, retaining control is largely in the hands of citizens, it said.
The message was underscored by President Emmanuel Macron who urged the public on Tuesday to remain "vigilant" and continue applying anti-infection measures such as keeping a safe distance from others, regular hand-washing, and wearing masks in public spaces.
Data released by the health department on Monday showed the number of people in intensive care had risen by 13 over the weekend, breaking a downward trend observed since April, when strict stay-at-home orders were in force. It rose by another four on Tuesday to a total of 388.
Twenty-nine new deaths were reported over the same period, bringing the country's toll to 30,294.
At the height of the outbreak in April, more than 7,100 people were receiving intensive care in French hospitals, which had 5,000 intensive care beds available when the crisis hit.
Thousands of confirmed new infections were registered last week, prompting some cities and regions to impose local restrictions amid reports of people ignoring social distancing and public mask-wearing guidelines.
'Probable second wave'
The rate of confirmed infections has exceeded 1,000 per day since late July.
Prime Minister Jean Castex on Monday urged France "not to let down its guard" in order to prevent a new national lockdown.
"We are seeing an increase in the figures for the epidemic which should make us more attentive than ever," Castex said.
Paris and the southern city of Toulouse joined the ranks of local authorities taking steps to oblige people to wear masks outdoors in certain situations, on top of the national requirement to cover up in shops and other shared spaces indoors.
Paris Mayor Anne Hidalgo had urged the city's police prefect to use his powers to make masks compulsory in busy outdoors spaces such as the banks of the Seine river, open-air markets and around train stations.
The scientific council said the government's response to a "probable second wave" of coronavirus infections will have to be different to the first.
It urged the authorities to put in place "prevention plans" for the largest and most densely-populated metropolitan areas, with localized home-confinement strategies to be tightened or loosened in step with epidemic development.
However the culture ministry confirmed that audiences of up to 5,000 will be allowed at events under "certain conditions" such as mask-wearing from August 15.
Yonathan Freund, an emergency doctor at Paris's Pitie-Salpetriere hospital, is among experts to caution against over-reacting.
"The situation in France today does not justify saying there has been a worsening," he told AFP.
"If there are 1,000 cases per day, it is because the virus is still in circulation, and it is normal," he said.
Epidemiologist Antoine Flahault said the focus of authorities seems to have shifted from preventing another run on hospital beds -- an acceptable risk approach -- to suppressing virus circulation to the lowest possible level, or a doctrine of "zero risk".