B.C. study touts school COVID safety, but authors are 'conscious of its limitations'

Vancouver -

School staff are no more likely to contract COVID-19 at work than they are in day-to-day life in their communities, according to a new study by B.C. researchers.

The study's results were released as schools are wrapping up for the summer following a challenging year that saw changing policies, closures and outbreaks for many educational facilities across the country. For teachers, parents and students that led to stress and uncertainty.

“You have to look at how many actually end up being infected -- not the contact, not the outbreak, not the letter you receive in the school because at the end of the day the outcome that matters is infection," said Dr. Pascal Lavoie, principal investigator of the study and pediatrician at BC Children’s Hospital.

The study, released on June 18 and still subject to a peer review, took a series of blood samples from school staff to test for SARS-CoV-2 antibodies, which would show whether they had been infected up until March 4, before the start of the third wave. The hope was to determine how many people had the virus, regardless of whether they felt symptoms.

But the study only looked at teachers and other frontline staff in the Vancouver school district, not in the Fraser Valley where hotspot communities like Surrey had sky-high per capita infections and some schools received dozens of exposure notices.

“I think we have to be conscious of the limitations of the study,” acknowledged Lavoie, but he said the Surrey school district did not respond to their request to participate.

His study co-author, a medical microbiologist at BC Children’s Hospital and clinical associate professor in the Department of Pathology and Laboratory Medicine at UBC, pointed out that Vancouver still had higher rates than much of the province and the country.

“There was a hybrid model in Vancouver high schools, but there was not a measurable change in levels in school staff compared to primary staff, where there wasn’t a hybrid model,” said Dr. David Goldfarb.

Both co-authors believe the results in high-transmission communities will be similar to school staff cases, and emphasized they started with a hypothesis but weren’t sure what the findings would turn up.

“I tried to walk into this as agnostic as possible without an idea of what we were going to find…I don't think we were set to prove schools were safe” said Lavoie when CTV News asked him to respond to criticism that health officials in B.C. were keen to support their decision to keep schools open. 

“Public health and government may have their own message, but we're primarily there to describe what's happening objectively and this was all arms-length from public health authorities, government sponsors, the school district and so on."

Of the 1,556 school staff researchers tested, 2.3 per cent tested positive for antibodies. According to the study, that number is similar to the number of infections in a reference group in the broader community which includes people of a similar age, sex and area of residence.

Source of infections the weakest point in the study

Whether or not a teacher had COVID can be proven with up to 95 per cent accuracy, according to the study’s authors, but where they got infected is much less precise.

The study included a survey of 1,689 school staff. Of those, 278 said they had close contact with a student or co-worker who had tested positive for COVID-19, but only five staff who were infected themselves believed it was likely they got infected while at work.

CTV News asked how they determined where the infections took place and whether participants had to self report, essentially making their own best guess, and they acknowledged that was the case.

“As part of the survey, the question’s we’d asked as to where they were infected and had they acquired it from school or outside of school in the home setting or friends in the community,” said Goldfarb, pointing out a few of the participants didn’t even know they’d had COVID before the serology test. “This study is not a definitive study on everything related to schools, but it’s one more study that provides insight specifically into asymptomatic infections.”

B.C. teachers wary of findings and assumptions

The B.C. Teachers Federation was interested in the findings, but wary of the study’s conclusions.

“It’s not reflective of the entire province, different districts had different experiences with the virus,” pointed out BCTF president, Teri Mooring. “It's really difficult to draw conclusions or take comfort in this broadly. I think we need to take a look at what's happening in August, as government has committed to doing."

She pointed out that elementary school-aged children won’t be vaccinated, and that 75 per cent of WorkSafeBC COVID claims approved for teachers have come from elementary teachers.

At least one doctor considers the study’s findings good news to sooth nervous families.

"I think it's very reassuring for parents," said CTV News medical specialist Dr. Marla Shapiro, who explained the study was completed when COVID-19 rates were higher in the community and vaccination rates were lower.

"If during this period of time we really saw that it mirrored what happens in the community. It really tells us that with mitigation strategies that our schools are safe places."

Shapiro said the situation "will only be better by the fall" as vaccination rates continue to rise, and Goldfarb pointed out the research is in line with other studies around the world.

“It's one other layer of information that would suggest there hasn't been widespread infection,” he said. “It certainly doesn't say there have been no infections in school."

The results of the study echo what B.C. provincial health officer Dr. Bonnie Henry has been saying for months. In a modelling presentation in April, Henry said only about eight per cent of COVID-19 cases in VCH schools recorded between Sept. 10 and Dec. 18 – whether they were students or staff – were connected to transmission in the school setting.

According to the provincial health officer, this showed that transmission in schools is being driven by transmission in the broader community, rather than the other way around.

Last week, Henry announced students and staff will see a "near normal" return to class in the fall. All students are expected to be back in the classroom for full-time, in-person instruction and the cohort system will come to an end. Guidance on mask-wearing in schools will be confirmed later in the summer.

“Full disclosure, my partner is a teacher and has been working in Fraser Health throughout the year and it is anxiety-provoking getting a notification and working in that class,” said Goldfarb. “But several of our participants did tell me this is reassuring knowing the systems in place were generally working in keeping transmission among staff low.”