Coronavirus in France is circulating four times more among people under the age of 40 than those over 65, France’s health minister said.
But he warned that contamination was on the rise among the elderly and more vulnerable too.
“We’re in a risky situation,” Olivier Veran said.
Like President Emmanuel Macron, Mr Veran ruled out the need for another total lockdown to combat the spread of the disease. But he said localised measures could be taken as cases grow in France and elsewhere.
“This is not a French exception, it’s a European dynamic,” he said.
France reported a 3,602 hike in new infections on Saturday, a smaller rise than the previous day. Earlier in the week, however, the number of daily cases reached a post-lockdown high.
Mr Veran said the cross-contamination between groups of the population – younger people between the ages of two and 40 and their elders – was already taking place.
Parties and gatherings where social distancing rules were not being respected were now the main source of contagion, as opposed to earlier in the summer when it had been in the workplace.
In many cases, younger carriers of the virus were asymptomatic or suffered fewer complications.