Early influenza season and severe impacts on children

By Ottawa Public Health - Dec 15, 2025

To: Ottawa Physicians and Nurse Practitioners
Date: December 15, 2025
From: Dr. Trevor Arnason, Medical Officer of Health
Subject: Early influenza season and severe impacts on children

Dear Colleagues,

The Children’s Hospital of Eastern Ontario (CHEO) is reporting an early and intense start to flu season leading to unprecedented volumes in the Emergency Department and a higher-than-usual number of flu cases and complications for this time of year. In the first two weeks of December, three children between the ages of five and nine have died from influenza A-related complications in the Ottawa and Eastern Ontario Health Unit (EOHU) regions. This news is likely to result in an increase in inquiries to local physicians and nurse practitioners about this year’s predominant influenza strain and the vaccine recommendations.

Ottawa Public Health is urging everyone six months and older to get their flu vaccine as soon as possible. Vaccination remains a key tool for protection against influenza, including severe outcomes and is especially important this season for children due to the rise in severe illness.

Despite the potential mismatch of the H3N2 strain contained in the vaccine and the H3N2 subclade K, vaccination is likely to provide some cross-protection, and the vaccine contains a H1N1 component as well as an influenza B component.

For more information about the 2025-2026 Influenza Season please see the following resources:

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