Cases of COVID-19 in reopened schools are inevitable, say Toronto public health officials, who are cautioning parents not to expect a shutdown of the entire school whenever a student or staff member tests positive.

“We expect to get cases related to schools,” said Dr. Vinita Dubey, the city’s associate medical officer of health, adding Toronto Public Health will take a “conservative” approach in how it handles cases in schools to ensure the risk of transmission is limited.

While TPH and school officials will be tasked with preventing the spread of COVID-19 when hundreds of thousands of children return to school in September, how those efforts will be communicated to the wider school community and the broader public is not yet clear.

Dubey said TPH is waiting for guidance for health units from the province on how to handle cases of COVID-19 in schools, including when to lockdown a school when the virus is believed to have been transmitted within it.

On Thursday, four teachers unions raised health and safety concerns with the reopening plan of Premier Doug Ford’s government, saying it puts students and staff in “significant and imminent danger.”

While parents and other adults are encouraged to work from home, 583 Toronto District School Board locations along with 196 Toronto Catholic District School Board locations are expected to reopen at the bell on Sept. 8 — but not for school as normal.

The province has already placed guidelines on schools, including class sizes, protocols for self-screening and other measures to help prevent the spread of the virus.

TPH will be responsible for monitoring the probable and confirmed cases of COVID-19 in the school system as they already do in the broader community.

Dubey noted TPH has a longstanding relationship with schools in handling infectious diseases, such as measles.

In their guides to safely reopening based on provincial guidelines, Toronto’s public and Catholic boards spell out identical, specific processes for how they will handle cases of COVID-19.

Students and staff will be asked to assess their symptoms before attending school. Toronto Public Health is also recommending active screening take place at the school, including a paper questionnaire or other means.

If a student starts to feel sick at school they’ll be separated from others until they can be picked up by their family, with a staff member supervising them while both wear personal protective equipment. The student will be asked to get tested at an assessment centre.

A staff member who becomes ill must immediately go home and get tested.

Staff and students will self-isolate while they wait for their results.

If the test is negative, they can return to school 24 hours after symptoms go away, under TPH rules. If it’s positive, students or staff can only return 14 days after symptoms first appear — as long as symptoms are “mostly gone” and do not require a confirmatory test or clearance letter.

If there’s a confirmed positive case, the supervisor or principal have to notify a list of school board officials as well as TPH.

“The TDSB takes its lead from Toronto Public Health, which is responsible for any necessary communications with regard to COVID-19 cases,” said spokesperson Ryan Bird said in a statement. “Should a presumed or diagnosed case of COVID-19 be present at one of our schools, we’ll work closely with Toronto Public Health to support contact tracing and inform individuals who may have been in contact with the affected person.”

Once a lab confirms a COVID-19 case, it notifies TPH directly. Public health has also told schools to contact them if they become aware of a suspected infection, in case there’s any delay from the lab so TPH’s work can begin as soon as possible.

The next step is for TPH’s case and contact team to investigate, identifying any close contacts the staff or student may have had.

Dubey said the planned school cohorts — small groups of students who will stay together throughout the day — will help, with the expectation schools will keep track of who is in which cohort and provide that information to TPH.

“The cohort is well-defined and you recognize that in the cohort while we want you to maintain physical distance as much as possible it may not always be possible throughout the course of the day,” she said. “And so, if there is a case in a cohort we might automatically say the whole cohort goes home — self-isolate that cohort until we can complete our investigation, for example.”

But parents should not expect an entire school to automatically be shutdown if there is one confirmed case, said Dubey, noting that measles are much more infectious than COVID-19, and when there have been confirmed cases of measles they have not closed the school.

But because of the risk congregate settings pose, Dubey said they will err on the side of caution and temporarily close a school if they lack immediate information to know who is at risk.

There is no clearly defined protocol for whether the entire school is notified when a suspected or positive case is identified, so how or whether all the parents of the school will be told is still unclear.

According to school plans: “TPH will contact positive cases directly and provide a letter directly to the other staff/students identified to have a high risk of exposure. Communications department to work with TPH on letters to school or community, as determined by TPH.”

Dubey said “communication is key” in these situations and the TPH process of notifying school communities about infectious diseases is also well established.

“We may send a notification to the whole school to say there’s been a case of whatever identified in your school, we’re letting you know so you can have your child watch for signs and symptoms,” she said. “That’s definitely part of our routine work in schools.”

Typically, she said, her agency works with principals to send a letter directly from TPH and set up a hotline where staff can answer questions from students.

Dubey said it’s important parents know the personal health information about students or staff will be protected, so the identity of anyone testing positive will be private. Those identified as close contacts will be told directly.

She said that privacy is important, including to prevent stigma when they are asking parents, students and staff to report possible symptoms.

As for public reporting, Dubey said a school is not generally considered an “institutional” setting like a long-term-care home because it’s not a primary residence. But public health is still working out how it may report school-related cases to the general public.

Shelley Laskin, a TDSB trustee for Ward 8 (Eglinton-Lawrence), said she shares the anxiety parents feel.

“I cannot blame them. They are worried about the health and safety of their most precious commodity, which is their child,” she said.

She said the board and TPH are providing as many details as possible to make parents feel confident in the plans that are in place.

“There has to be a level of understanding that people are working flat out to give them the answers they need,” she said.

Isaac Bogoch, an infectious disease specialist at the University of Toronto and University Health Network, said “there’s an art and a science to contact tracing” work TPH will do with a school outbreak.

Typically, TPH would try to find out who was truly a close contact with the infected person — whether they took the bus with someone, were in a carpool or elsewhere outside school.

It’s extremely unlikely one case would create the need to shut an entire school down or even a classroom, he said.

“You can envision a scenario where a kid comes to school is bound to be COVID-19 positive, but when you look at the layout of the class, how the class was conducted and the insurance of physical distancing, it could very well be that there are truly no close contacts,” he said. “People might need to monitor their symptoms.”

But Bogoch said even with the best-laid plans, it’s inevitable there will be cases in schools. What’s important are the steps in place to limit the risk of transmission.

“The whole point of all these provincial plans is really to prevent the transmission of this infection if it is introduced into a school,” he said.

How successful the school reopening will be depends on how the provincial guidelines are followed on the ground, he said.

The city’s board of health chair Coun. Joe Cressy said as the fall approaches, there has to be a recognition that “we have to learn to live with COVID.”

“The option of staying locked in our homes forever clearly has enormous social health and economic costs,” he said. “So getting to a place where we can reopen schools safely is where we want to be.”

Jennifer Pagliaro is a Toronto-based reporter covering city hall and municipal politics for the Star. Follow her on Twitter: @jpagsh