Public health officials and infectious diseases specialists are urging caution for seniors and those with chronic illnesses ahead of what could potentially be a more severe flu season than usual this fall.
With fewer Canadians opting to get their flu vaccines over the past two years because of a lull in influenza cases and the end of COVID-19 related health restrictions this spring, Dr. Matthew Oughton says there are more people now at a heightened risk of getting the flu.
The infectious diseases specialist at Montreal's Jewish General Hospital said the dropping of measures like mask mandates can also explain why Canada is experiencing such an unusual trend in influenza cases this year.
Cases began popping up in April and through June. That's much earlier than the usual November to March trend the country sees, but not surprising either, Oughton said.
"I think we've actually done an inadvertent experiment in proving how much we can eradicate influenza by non-pharmaceutical measures: physical distancing, wearing masks, hand hygiene," Oughton said. "They seem to work exceptionally well."
By the end of April, data from the Public Health Agency of Canada showed a 9.6 per cent test positivity rate for influenza A infections across Canada, largely driven by a spike of cases in Quebec. The rate of infection was above what's usually anticipated during the season, the agency said.
The 1,637 influenza A cases reported are more than double those reported at the same time in 2019. It was the leading strain of the influenza virus over both years.
Positive Influenza A tests by week in Canada since March 1, 2022
On Wednesday Quebec's public health director announced the province would be kicking off its flu vaccine campaign a whole month sooner than usual to catch up. By October, Quebecers will be able to get both their COVID-19 booster and flu shot at the same time.
Dr. Luc Boileau said it's being done in the hope of avoiding a resurgence of flu and COVID-19 outbreaks that could threaten to overwhelm hospitals.
"We're taking all the care that's needed to be well prepared for that," Boileau said. "We expect it to be something that will ease the capacity of the hospitals."
He pointed to the earlier onset of flu outbreaks in the Southern hemisphere.
Earlier this year, Australia endured its worst flu season in recent years, and data from Australia's Department of Health and Aged Care show infections were higher than the five-year average — with infections notably spiking, then dropping, earlier than usual.
The lull of influenza cases over the pandemic means scientists have less health data to interpret, Oughton said, making it harder for them to predict which influenza strains are most likely to be dominant this fall.
"The seasonal flu vaccine has to be based on the best guess. In a setting where there are very few circulating flu strains, that guess from last year's seasonal flu vaccine did not produce a very good match," he said.
"Let's all cross our fingers and hope that we don't see a big surge of influenza," Oughton added. "But I think the prudent approach is to assume that it's going to happen, and to learn what we can from the data that we have from other parts of the world."
Nimâ Machouf, epidemiologist and infectious diseases consultant at Le Gardeur hospital in Terrebonne, Que., says she worries vaccinations alone won't be enough to prevent subsequent waves of the respiratory viruses.
"There are no more prevention measures, so we will have influenza and we will have COVID-19 all at the same time," said Machouf, who holds a PhD and lectures at the Université de Montréal.
She said mask mandates need to be reinstated, but with the ongoing election, she doubts any candidate will bother to push the unpopular measure.
"Unfortunately the political reasons are now governing over [our] health measures," said Machouf.
At the very least, the province could step up and fix the ventilation problems in major public indoor spaces like schools, she said. Or let people take home more than one kit of rapid COVID-19 tests per month.
"It will have a huge impact on the diminution of the spread of these viruses. But it costs money."