In some regions of Canada, experts in infectious diseases are noting an uptick in indicators of COVID-19 in wastewater and other disease metrics. This rise coincides with the return of students and teachers to schools and an increase in indoor gatherings. This pattern of late-summer escalation has been consistent over recent years, prompting medical professionals to urge Canadians to take preventive measures such as vaccination, maintaining hand hygiene, and staying home when unwell.
On a national scale, the current level of viral activity in wastewater related to COVID-19 is classified as moderate. Elevated levels have been observed in cities like Vancouver, Calgary, Edmonton, Winnipeg, Montreal South, and Prince Edward Island, according to the federal government’s wastewater monitoring dashboard. Dr. Lynora Saxinger, an infectious diseases specialist at the University of Alberta, cautioned that the trend suggests a potential late-summer rise followed by a surge in the fall and winter, although the situation remains unpredictable.
The percentage of positive COVID tests among individuals visiting emergency departments for respiratory symptoms nationwide is currently at 8.5%. However, for the week ending March 22, this rate dropped to nearly two percent, marking the lowest level this year. While the magnitude of late-August increases varies annually, the overall upward trajectory as summer concludes is a recurring occurrence. For instance, positivity rates reached 16.9% at the end of August in 2024 and 13.4% during the same period in 2023.
Similar to influenza, protection against COVID-19 from prior infection or vaccination diminishes over time due to the virus evolving and giving rise to new variants. Dr. Saxinger highlighted that the existing variants are derived from Omicron, which has been predominant since late 2021. The current Omicron subvariant, XFG, is causing mild to moderate illness, as noted by Lawrence Goodridge, a microbiology professor at the University of Guelph. Goodridge expressed confidence that forthcoming vaccines should offer protection against XFG.
As fall approaches, Dr. Saxinger emphasized the importance of recalling past experiences, particularly the increased indoor gatherings and drier air, which are common during this season. She urged individuals to stay home from work or school if feeling unwell and stressed the ongoing risk of widespread COVID infections causing significant harm, especially for unvaccinated individuals with underlying health conditions or aged over 65. While the potential for severe cases remains, experts do not anticipate a resurgence of pandemic-level case surges.
Dr. Isaac Bogoch, an infectious diseases specialist at Toronto General Hospital, highlighted vulnerable groups such as individuals over 65, particularly those above 80, residents of long-term care facilities, and those with specific underlying medical conditions. He underlined the importance of seeking advice from healthcare providers regarding COVID vaccination, especially as vaccines are expected to become available across Canada in the upcoming fall.