PARIS — As a second lockdown appeared inevitable amid skyrocketing coronavirus infections, the scientists advising the French government in October warned that keeping students in their classrooms meant it would take longer to tame the surge.
The government kept the schools open anyway, even as the country became an epicenter of the second wave of the coronavirus in Europe. French leaders decided that they would try to subdue the surge, while also trying to minimize economic and academic damage by keeping children learning where they do it best: in school.
Five weeks into a second nationwide lockdown, France, like much of Europe, has proved that it is possible to bring the rate of known infections down, even with schools open.
It is a lesson that has been taken up late in the United States, where Chicago, Boston, San Francisco and other cities, have made it a priority to keep bars and restaurants open — though not necessarily for indoor service or at full capacity — even as they have closed their schools.
Many European countries, including France, have made the opposite choice: keeping schools open but closing restaurants and bars.
In France, 11 percent of coronavirus tests are coming back positive but students have kept going to school, while New York City shut its public schools on Nov. 19, after the positive test rate reached 3 percent.
But recent studies have shown that young children, at least, are low transmitters of the virus, and at least some American officials are reconsidering their approach: Mayor Bill de Blasio of New York abruptly decided on Sunday to reopen elementary schools while keeping upper grades closed, and other districts around the country have made or announced similar moves.
Allowing schools to remain open has been one of the most significant departures from Europe’s initial lockdowns last spring.
“The first lockdown was horrible,” said Marine Huguenin, who was watching her two daughters play at a Paris park, which was filled with strollers and masked parents after school on a recent afternoon.
During the earlier lockdown, the entire family was stuck inside, she said, with Ms. Huguenin and her husband looking after their children during the day, then catching up on work between 9:30 p.m. and 1 a.m.
The numbers tell the story of France’s progress so far. In early November, the number of new cases in France in a seven-day period soared to more than 80 per 100,000 people; as of Sunday it had dropped to 17 per 100,000.
“Obviously, the decline has been slower because schools are open, but we had to find a middle ground,” said Yazdan Yazdanpanah, an infectious disease specialist and a member of France’s Scientific Council, which advises the government on the pandemic. But, he added, the slower drop in infections has been offset by positive effects on education, mental health and the economy.
The trade-off has been generally well-accepted in an otherwise contentious lockdown during which an increasing number of people have challenged restrictions on movement and business.
In Paris, keeping schools open has shifted the mood in a city that lived through one of the world’s strictest lockdowns in the spring.
At the time, Paris felt like a ghost town, with every inch of the city — from small residential streets to the Champs-Élysées — deserted. This time, things seem much nearer to normal. Chairs are stacked inside closed cafes and restaurants. But neighborhoods come to life in the mornings and afternoons as parents take their children to and from school, and older students linger on sidewalks with studied indifference.
Clusters have appeared in schools throughout France, though not in “worrying numbers,” said Dr. Yazdanpanah, the infectious disease specialist.
With classrooms open, parents have been able to focus on work at home or commute to their workplaces, which has helped blunt the second lockdown’s blow to the economy.
The Bank of France estimated that economic activity this month would be 12 percent below normal — far less than the 31 percent drop experienced in April.
Most European countries, including Britain, France, Germany and Spain, have kept schools open even as the continent remains among the worst-hit. A few countries, like Austria, the Czech Republic and Italy, have closed schools, in part or in full.
The country’s 12 million students in primary and secondary schools engaged in online learning, but soon, teachers and education officials warned that many children had fallen behind.
“It reinforced our conviction to keep the schools open, for education and social reasons,” said Sophie Vénétitay, a teacher and union official.
Meanwhile, new studies suggested that despite early fears, keeping schools open, while not without risk, could be relatively safe so long as rules to limit the spread of the virus were in place.
In August, a report released by the European Center for Disease Prevention and Control said evidence “indicates that closures of child care and educational institutions are unlikely to be an effective single control measure for community transmission of Covid-19.”
Most studies on transmission now suggest that children younger than 10 spread the virus less efficiently than adults do, but that teenagers become infected and spread the virus just as much as adults. So keeping high schools open safely is trickier, especially if community transmission is high — making social distancing rules even more important.
After reining in the first wave of the epidemic, France saw infections begin rising again in August as people resumed socializing and the government failed to effectively carry out public health measures of testing, tracing and isolating.
By October, infections were skyrocketing across most of Europe.
But even after a warning from his scientific advisers, President Emmanuel Macron announced that France’s schools would remain open, as nonessential businesses were ordered closed. “Our children cannot be permanently deprived of instruction, education, contact with the school system,” he said.
Henri Bergeron, a sociologist at the Paris Institute of Political Studies, the elite university known as Sciences Po, and a co-author of a book, “Covid-19: An Organizational Crisis,” said: “This time, health priority is mixed with economic priority.”
To address concerns as cases ballooned, education officials slightly tightened rules, including lowering the age for mandatory mask-wearing to 6 years old from 11. Many schools staggered hours for parents to drop off and pick up their children, and have adjusted lunch periods to lessen crowding. In many high schools, students now take turns, spending half their days in school and the rest at home.
Three months into France’s school year, schools have not become a major driver of infections, according to health experts. And the number of students who tested positive in the seven days that ended on Thursday dropped 44 percent from the week before, according to figures released by the Education Ministry. The latest figure translates to 0.06 percent of the 12 million schoolchildren in France.
On Friday, out of 61,500 schools nationwide, only 19 primary schools, three middle schools and three high schools were closed because of outbreaks.
Outside Turgot High School in Paris, small groups of students chatted and smoked after the end of their classes on a recent afternoon. Some said they thought students were being infected outside school, when they met on weekends, sometimes at classmates’ parties.
Jeanne Piffaut, 17, said she found it hard studying alone and being unable to ask her teachers questions in person.
“I’m worried that the situation will get worse,” she said, “and that schools end up closing.”