Flu activity is increasing rapidly across Canada, with hospitalizations nearly doubling in a single week as the H3N2 strain becomes dominant. Recent national surveillance data highlights growing pressure on hospitals and renewed concerns for children, older adults, and people living with chronic lung conditions.
Flu Cases and Hospitalizations Are Increasing Nationwide
New federal surveillance data shows that flu infections have risen sharply, with more than 11,600 new cases detected in mid-December. Nearly three in ten flu tests returned positive results during that period—an increase of more than 70 per cent compared to the previous week.
Hospitalizations linked to flu also climbed significantly, rising from 3.9 to 6.2 per 100,000 people in just one week. Reported outbreaks more than doubled across the country, with widespread flu activity now observed in multiple provinces, including Ontario, Quebec, British Columbia, Alberta, and Saskatchewan.
These trends indicate that flu transmission is accelerating as Canadians spend more time indoors during the winter months.
Related reading: Global News — Flu hospitalizations rise sharply as H3N2 spreads across Canada
Children and Older Adults Face Higher Risk
Recent Canadian surveillance data show that young children and older adults continue to experience the highest rates of severe illness from flu. Hospitalization rates are highest among adults aged 65 and older and children under five years old, while a significant proportion of cases are being reported among those 19 years and younger.
Pediatric hospitals in parts of Ontario and Alberta are reporting increased admissions related to flu, underscoring how quickly the virus can spread in school and child-care settings.
Why H3N2 Is Causing More Severe Illness
Flu is not a single virus but a group of viruses that change each season. This year, influenza A (H3N2) is the most commonly detected strain in Canada. Historically, H3N2 has been associated with more severe illness and higher hospitalization rates, particularly among older adults and people with underlying health conditions.
Flu can lead to serious complications, including pneumonia, worsening of existing lung disease, and other systemic impacts that may require hospitalization. These risks highlight why the flu should not be dismissed as a mild respiratory infection.
Related reading: CTV News — Don’t think of the flu as a cold. What to know about H3N2, a fast-spreading, ‘severe viral infection’
Schools and Indoor Settings Drive Transmission
Flu transmission is especially high in indoor environments where people gather for long periods of time. Schools, workplaces, public transit, and long-term care settings can all contribute to rapid spread, particularly when ventilation is limited.
Children are often among the first to be exposed, and infections can then spread quickly to family members and caregivers at home.
Immunization Remains One of the Best Ways to Protect Lung Health
Even when circulating strains vary, the seasonal flu vaccine continues to play a critical role in reducing the risk of severe illness, hospitalization, and complications—especially for people living with asthma, COPD, lung cancer, or other chronic lung conditions.
Visit Lung Health Foundation’s Immunization page to learn more about flu vaccines, eligibility, and how immunization supports lung health.
