'You can't see them'

·4 min read

Public health officials insist COVID-19 transmission in schools is limited, but one epidemiologist questions the data — and lack thereof — being used to back that claim.

Dr. Brent Roussin has yet to waver from his steadfast belief schools are safe places for K-12 students in Manitoba, despite a provincial test positivity rate that has reached upwards of 14 per cent in recent days.

The chief provincial public health officer has repeatedly said, as he reiterated during a news conference Tuesday: “We’re not seeing a lot of transmission in schools.”

Amy Greer, an epidemiologist at the University of Guelph, has heard similar rhetoric in Ontario since students returned to school this fall. She isn’t quite as confident as Roussin or the leadership in her home province.

“We haven’t really looked,” said Greer, who researches the introduction, spread, dynamics and control of infectious diseases in populations.

“If many, many children are asymptomatic, you’re not going to know. You can’t see them. You can’t see that you have an issue if many of those children are asymptomatic, unless you do more targeted surveillance and testing to see what’s actually happening in those classes that have had an exposure.”

The general scientific consensus is children under 10 who become infected with SARS-CoV-2 are less likely to become severely ill and spread it to others in comparison to older patients.

Early evidence suggested youth are also far less likely to become infected with the novel coronavirus, but growing research shows children are often asymptomatic and thus, infections may go under the radar.

Among recent “red flags” for Greer are the results of a new study of common symptoms in children in Alberta, which was published last week in the Canadian Medical Association Journal.

The authors analyzed the results of hundreds of children who underwent testing between April and September. Of the 1,987 who had a positive result, more than one-third reported being asymptomatic.

That means 36 per cent of students who are infected pass a self-screening test and the preventative “half-measures” — Greer’s definition of the back-to-school approach, citing politicians’ decisions not to cap class sizes or upgrade ventilation systems, despite expert recommendations — are the last line of defence, she said.

Meantime, Greer said there are many instances where adults contract the virus and it is difficult to attribute where they became infected. One explanation could be that an asymptomatic student brought the virus home and by the time a parent shows symptoms and the household gets tested, the student receives a negative result because they have recovered, she said.

“I’m uncomfortable saying transmission (in schools) is low, because I don’t think we have the right data.”

Last week, Ontario unveiled a voluntary testing program for asymptomatic students and staff in regions with high infection rates.

A public school pilot in Thorncliffe Park, a Toronto neighbourhood that has a 16 per cent positivity rate, has since found four per cent of the school had COVID-19, including 18 students and one staff member.

When pressed about whether Manitoba would follow suit, Roussin said Tuesday such an initiative would require more testing capacity, so the province has no immediate plans to implement a similar pilot.

While Greer acknowledged the pilot will result in more data collection, she said contract tracers should ideally be following up with and ensuring all students and staff who have been exposed to the virus get tested, even if they feel healthy.

The widespread testing of children for antibodies would also be helpful data to collect to understand how transmission is occurring in schools, she said.

Caroline Colijn, an infectious disease modeller at Simon Fraser University, echoed Greer’s comments during a phone call from Burnaby, B.C. “I don’t think any scientist believes there’s a magic COVID eraser in schools.”

She suggests investigators document the environments in which school clusters and outbreaks occur to determine what factors contribute to them.

Colijn added it is key officials be transparent with families about what’s going on in schools, in order to maintain trust in the pandemic response.

Upwards of 330 Manitoba schools have recorded a COVID-19 exposure to date, according to a spreadsheet compiled by an anonymous parent who draws from provincial data, news reports, and crowdsourcing.

The spreadsheet has started to beat the province at making exposures public.

Maggie Macintosh, Local Journalism Initiative Reporter, Winnipeg Free Press