Are schools driving Alberta's COVID-19 spread or are they the victim of it? Dr. Hinshaw believes the latter
'It does seem to be the reverse, with community transmission causing increased pressure in schools'
The reopening of schools has been highlighted as a potential driver of recent COVID-19 surges in other parts of Canada and around the world, but Alberta's chief medical officer of health doesn't believe they are causing the high rate of new cases in this province.
"I do not see evidence in Alberta of schools driving that increasing community transmission," Dr. Deena Hinshaw said.
"It does seem to be the reverse, with community transmission causing increased pressure in schools."
Alberta continues to see record-high levels of COVID-19 cases among school-aged kids, but that is not unique to their demographic. Virtually every age group in Alberta has recently seen its highest rate of new cases on record, as the province experiences its largest surge in virus spread to date.
Researchers and physicians in other jurisdictions have been warning that schools may be a significant driver of COVID-19 spread, after numbers surged shortly after classes resumed.
The timing of Alberta's latest surge is consistent with what you would expect if schools were driving an increase in spread, says Malgorzata Gasperowicz, a developmental biologist and independent researcher who has been tracking Alberta's COVID-19 data closely.
Gasperowicz had previously warned in October that, given the trajectory in Alberta's COVID-19 spread at the time, the province could be seeing 1,000 cases per day by Nov. 11. Alberta nearly reached that level on Nov. 7, when the province reported 919 new cases of the disease.
She noted that, after a period of slow growth in the summer, the disease spread suddenly accelerated in mid-September to a pace where new cases were doubling every 2½ weeks.
"It sort of switched into this faster growth around Sept. 17, which is 16 days after the schools reopening," she said.
She cautioned that this correlation does not imply causation. In other words, it doesn't prove schools are driving the spread, but it doesn't rule it out.
"For me, that shows we cannot dismiss schools as a contributor to the spread," Gasperowicz said.
Schools and COVID-19 surges in other places
Quebec experienced a similar surge of COVID-19 cases in September, and some physicians in that province have been drawing a link to the resumption of in-person classes.
"Schools were the driver to start the second wave in Quebec, although the government did not recognize it," Dr. Karl Weiss, president of the Association des Médecins Microbiologistes Infectiologues du Québec, told the Montreal Gazette last week.
More physicians recently spoke out about the situation to CBC Montreal, noting many schools are old and have poor ventilation. Quebec has also had relatively loose requirements for students wearing masks.
Still, Quebec's public-health director, Dr. Horacio Arruda, maintains schools are not the main cause of the province's recent surge. He says the cases among school-aged kids are more of a reflection of transmission in the broader community.
Globally, the reopening of schools has also been connected to increases in viral-transmission rates, according to University of Edinburgh researchers who analyzed data from 131 countries and published their findings in The Lancet, a prestigious medical journal.
On Tuesday, Manitoba announced a provincewide "code red" situation due to rapid growth in COVID-19 cases. The province ordered the closure of non-essential retail stores, gyms, movie theatres, salons and churches, as well as a shutdown of recreational facilities and sports activities. Social gatherings of any kind will also be banned as of Thursday.
Manitoba schools and child-care centres will remain open, however. Despite hundreds of cases among students and staff, there have been only a small number of confirmed transmissions directly within the school system, said Manitoba's Chief Provincial Public Health Officer Dr. Brent Roussin.
Case growth and origins
In Alberta, cases of COVID-19 have been rising quickly among older kids and teens, but not quite as fast as among the 20-to-29 age group, on a population-adjusted basis.
On average over the past week, there have been about 18 new daily cases per 100,000 people aged 10 to 19, compared with about 23 new daily cases for people in their 20s.
Case growth has been significantly slower among kids aged five to nine, at about 10 new daily cases per 100,000 children in that age range.
There's also the source of infection to consider, which can be difficult to determine.
But Alberta Health says the data points more heavily toward non-school settings than in-school transmission.
From September to mid-October, Hinshaw said just six per cent of COVID-19 cases among school-aged kids were found to be acquired in school.
Alberta Health also said last week that slightly more than half of active cases — across all age groups — were of unknown origin. That figure has been increasing lately, as contact tracers struggle with the sheer volume of newly infected patients.
All this makes pinpointing the primary drivers of the recent surge in cases a difficult task.
"Everything is tangled together," Gasperowicz said.
She noted there could also be a "data acquisition bias" when it comes to kids, in particular.
"A big percentage of children are asymptomatic, so we don't test them," she said. "So there could be invisible spread."
From all the available evidence, though, Hinshaw believes schools, themselves, are not a primary driver of Alberta's latest surge.
She says there are "many factors" that have changed since the summer that are likely contributing to the spread.
"With the fall and cooler weather, people are spending more time indoors," Hinshaw said. "There's less of those opportunities, perhaps, for socializing outside that we had in the summertime. And, of course, there are other activities that start up in the fall in addition to school. There's other, recreational-type activities that people are engaging in."