Published on Dec. 19, 2025, 6:20 PM
Does it feel like everyone around you is sick? This year’s flu season has had a vicious start.
Flu season was off to an early — and vicious — start this year, with hospitalizations up across the country. CHEO, eastern Ontario’s children’s hospital in Ottawa, says it has seen “unprecedented” numbers of sick patients lately, with nearly 300 young adults visiting the emergency department in a single day, CHEO’s vice-president of acute care services, Karen Macauley, told CBC News.
Across all Ontario hospitals, ICU admissions jumped 127 per cent in a week, the Ontario Hospital Association said on December 17.
What does this have to do with the weather?
“Many viruses, including rhinovirus – the usual culprit for the common cold – influenza, and SARS-CoV-2, the virus that causes COVID-19, remain infectious longer and replicate faster in colder temperatures and at lower humidity levels,” public health nurse Libby Richards explained in 2024.
“This, coupled with the fact that people spend more time indoors and in close contact with others during cold weather, are common reasons that germs are more likely to spread.”
Richards says cold weather can change the outer membrane of the influenza virus, giving it a more solid and rubbery coating that makes person-to-person transmission easier.
“It’s not just cold winter air that causes a problem,” she says.
