Ottawa Public Health has declared the start of the 2026-2027 influenza season in the city as of Oct. 31.
The declaration follows two consecutive weeks in which more than 5 per cent of respiratory lab specimens tested positive for influenza, the threshold the health unit uses to mark the official start of the season.
According to Ottawa Public Health, the percentage of respiratory specimens positive for influenza was 5.3 per cent in the week before the declaration. For the week ending Oct. 31, that figure rose to 6.6 per cent.
The upward trend has continued into November. For the week ending Nov. 7, influenza positivity was 6.1 per cent.
It is not only test results that are climbing. Ottawa Public Health said hospitalizations for influenza have also been increasing since the season began.
The declaration was communicated in a memo dated Nov. 12 from Dr. Alysha Ahmed, associate medical officer of health, addressed to Ottawa physicians, nurse practitioners and midwives.
The memo, posted on the health unit's website, outlines the local influenza picture for the 2026-2027 respiratory season to date.
For Ottawa residents, the declaration signals that flu is now circulating at seasonal levels in the community rather than at the low, off-season rates seen in the summer months. The 5 per cent positivity benchmark is what Ottawa Public Health uses to formally mark the shift each year.
The data behind the declaration comes from respiratory lab specimens collected in the city. The week-by-week figures show the virus gaining ground quickly through late October, crossing the 5 per cent line in the week before the declaration and peaking at 6.6 per cent for the week ending Oct. 31.
The slight dip to 6.1 per cent in the most recent week does not signal the end of the season, as positivity remains above the threshold used to declare it. Ottawa Public Health continues to track positivity along with hospitalizations as key indicators of how the season is unfolding.
Further details, including the health unit's full epidemiological summary for the respiratory season to date, are available on the Ottawa Public Health website. The agency recently consolidated its Ottawa Public Health and Parenting in Ottawa web content into a single site.
