Two months later, her twin boys in kindergarten and their older brother in second grade are frustrated by Internet glitches, missing their friends and itching to go back. So the family has opted to switch to a hybrid model of in-person and e-learning this month.

“They’re super excited, but now that the numbers go up, then I start to question my own decisions,” said McGivery. It can be hard to make sense of the local coronavirus data, never mind the broader torrent of sometimes conflicting information on children, schools and covid-19.

“It’s so stressful. . . . I have to be a mom, an epidemiologist, a teacher — everything.”

It’s been an uncertainty-ridden time for parents across the country. As cases in Canada surge again, provinces are closing businesses, reimposing restrictions on public spaces and urging people to curb private gatherings.

Still, as in European countries that are also tightening their rules, Canada is prioritizing keeping its schools open. All 13 provinces and territories are holding classes in person; in only some are hybrid or remote learning even options.

In the United States, in contrast, nine states and territories have ordered some or all schools to hybrid or remote learning only, according to a tally kept by Education Week. Individual districts in other states are limiting or banning in-person classes.

The incidence rate of covid-19 in people under 20 has increased since schools reopened, a trend the Public Health Agency of Canada says could be tied both to a growing number of school outbreaks and an increase in testing for that age group.

Officials are responding by isolating sick pupils, quarantining classes hit by the virus and, in some cases, closing schools temporarily. But they’re resisting the blanket closures and wholesale shift to e-learning of the spring.

“On balance, it’s been as expected,” said James Kellner, head of the pediatrics department at the University of Calgary. “And how that’s been has been concerning, but not terrible so far.”

Officials say reopening schools is key to restarting the economy, and the longer they’re closed, the greater the effects on students’ education and mental health.

“I think we need to do everything we can to maintain our schools in terms of keeping them open,” Howard Njoo, Canada’s deputy chief medical officer of health, told reporters last week.

But guidance on when to keep sick pupils home and when to send them to class has created confusion. Testing protocols have changed. Schools have closed with little notice, creating new challenges for parents, students and educators.

Some officials are revamping plans and giving parents options to change theirs. The Toronto District School Board, Ontario’s largest, said 7,800 elementary school students switched from in-person to e-learning in mid-October, during Thanksgiving week here, the first chance to do so. Some 3,000 went the other way.

Infectious-disease specialists consider schools a mirror of their communities. The key to safeguarding them, they say, is to control the spread of the coronavirus outside them. So the surge in cases here — recent daily counts are eclipsing records set in the spring — could pose a risk.

Infectious-disease specialists say that most cases detected in Canada’s schools appear to have been acquired outside them and that large outbreaks in schools have been relatively infrequent, though they note that data is sometimes inconsistent and that strains on testing mean some cases are being missed.

“The schools aren’t making the communities worse,” said Zain Chagla, an infectious-disease physician at St. Joseph’s Healthcare Hamilton. “The communities are making the schools worse.”

In Quebec, home to nearly half of Canada’s cases and two-thirds of its deaths, in-person attendance is largely mandatory. Quebec Premier François Legault has called the approach a “calculated risk.”

“There is an even greater risk if we keep children at home,” he said in September.

But the problem, Caroline Quach said, is “when we opened schools, community transmission was rising.”

“It was creeping up . . . and trickled down to schools,” said Quach, head of infection prevention and control at Montreal’s CHU Sainte-Justine hospital.

Canada had developed a patchwork of approaches. Each province and territory is responsible for its own plans; some decisions are left to local school boards. Atlantic Canada has kept community transmission low; some provinces have no school cases. Regions with lots of community spread have more of them.

Alberta has reported transmission within 87 schools, according to Deena Hinshaw, the province’s chief medical officer of health. Most resulted in just one new case. Hinshaw called the numbers “significant,” but said they need to be kept in perspective: School transmissions have accounted for roughly 6 percent of coronavirus cases in those ages 5 to 19 since Sept. 1.

“Schools are not a main driver of community transmission,” Hinshaw told reporters last week. “Our rising community transmission is resulting in more school exposures.”

Quebec and Ontario together account for roughly 80 percent of Canada’s cases. Twenty-seven percent of Quebec’s public schools and nearly 12 percent of Ontario’s report at least one active case. Around 40 percent of Ontario’s 2,230 school-related infections were logged in the past two weeks.

“The resurgence does not appear to be primarily driven by the reopening of schools,” Eileen de Villa, Toronto’s top doctor, said last month. “The number of outbreaks in schools so far has been small, and they usually involve less than five students and staff.”

Amid rising case counts, Quebec has announced new measures, including mandatory masks for high-schoolers in hard-hit areas and a requirement that some of them learn from home every other day.

Infectious-disease specialists caution that the virus could be spreading under the radar. Systems for testing, tracing and isolating carriers are under strain, and asymptomatic children aren’t being tested widely.

“With less real-time ability to look at community cases, if there’s a change, we’re less and less likely to be able to detect it,” said Matthew Oughton, an infectious-disease specialist at Montreal’s Jewish General Hospital.

A lack of preparation for this very different school year has deepened uncertainty. One knotty issue has been the sniffles. Guidelines in some districts required pupils with a runny nose — a symptom common to allergies, the flu and other maladies that are not covid-19 — to stay home for 14 days or produce a negative test before returning to class.

Within days of reopening, families with sniffling students swarmed testing centers that had failed to scale up testing for what infectious-disease specialists said was a predictable onslaught. Several provinces dropped the runny nose from their checklists, but that’s been controversial, too: For some children with covid-19, it was their only symptom.

Worries persist that reopening plans have been inadequate. Advocates continue to call for smaller class sizes, improved ventilation and remote options.

“With more cases being unrecognized and coming into schools, there needs to be a shift in the strategy toward preventing the spread in the classroom,” said Nisha Thampi, a pediatric infectious-disease physician at the Children’s Hospital of Eastern Ontario.

David Fisman, an epidemiology professor at the University of Toronto, said data shows the positive test rate in children under 10 in Ontario has shot up even as the number being tested has fallen; one explanation, he said, could be “amplification in schools.”

Fisman said governments are leaving “easy wins” on the table.

“Whether or not covid is being amplified in schools or being introduced from outside schools, having smaller class sizes would be highly desirable,” he said. “It’s just fewer linkages. It’s just math.”

Online learning was available this fall for Caitlin Irwin, an eighth-grader at Franco-Cité in Ottawa, and her brother Jackson, an 11th-grader. But they were enrolled in specialized programs that were unavailable remotely, and they missed their friends. So they decided to attend in person.

It didn’t take long for the signs to pile up that something at the French-language Catholic school was amiss. There was one covid-19 case. And another.

Twice, so many teachers were quarantined for possible exposure to the coronavirus that the seventh and eighth grades were ordered to study at home for two days.

Then, on Oct. 7, public health officials declared an outbreak at the school and closed it. There have been 21 cases at the school this year.

It’s the kind of tumult for which their mother, a wedding planner, was prepared in this pandemic year.

“We weren’t surprised that the whole school closed,” Erica Irwin said. “But it seemed to come faster than we thought.”