The Canadian respiratory virus surveillance report reveals a concerning rise in influenza cases,with the weekly hospitalization rate currently at 2.9 per 100,000 population. Dr. Jesse Papenburg, a pediatrician and infectious disease specialist at the Montreal Children’s Hospital,warns that this is just the beginning. “At the moment, we have not reached the peak of the influenza season, this remains data which is at the start of the epidemic. it can be much higher than that,” he commented.
The epidemic threshold was exceeded in the week ending December 21, marking the official start of the seasonal influenza epidemic in Canada. this threshold is defined as 5% of positive tests for influenza, coupled with at least 15 weekly detections. As then, the curve of infections has steadily climbed. Recent data from the National Institute of public Health of Quebec (INSPQ) shows that 11.3% of influenza tests in clinical laboratories across Canada are positive, with Quebec reporting a slightly lower rate of 10.9%.
Ascending Phase of the Epidemic
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Dr. Papenburg, who also serves as an associate member in the Department of Epidemiology at McGill University, explains that we are in the ascending phase of the epidemic. “The season has started and in the weeks that follow the incidence rates will continue to increase and we will still see many cases of influenza for the coming weeks,” he said. Typically, an influenza season lasts 10 to 16 weeks, meaning we are far from the peak. “I think the next few weeks are going to be more difficult in terms of influenza,” he added.
he emphasizes the heightened risk for vulnerable populations. “Children under 5 years old, but particularly children under 2 years old, as well as our elders, people aged 65 and over, but especially 75 years and over, are at higher risk of hospitalization and complications of their influenza infection,” he says. Dr. Papenburg predicts a typical influenza season that will cause severe illness, particularly among these high-risk groups.
Vaccination: A Critical Defense
Despite the rising cases, Dr.Papenburg reminds us that it’s not too late to get vaccinated. Protective antibodies develop between 7 and 14 days after receiving the vaccine.“It is not too late because we are still in the ascending phase of the epidemic. The next few weeks are going to be worse than what we have right now. Someone who gets vaccinated now will offer themselves protection during this period when there is the greatest circulation of influenza,” he advises.
While vaccine effectiveness varies annually, the average protection is 50%, meaning vaccination reduces the risk of hospitalization by half. Estimates for the 2024-2025 season’s vaccine effectiveness are expected to be available in February or March 2025.
Key Insights at a Glance
| Key Metric | Data |
| Weekly hospitalization rate | 2.9 per 100,000 population |
| Positive influenza tests in Canada | 11.3% |
| Positive influenza tests in Quebec | 10.9% |
| Average vaccine effectiveness | 50% |
As the influenza season progresses, staying informed and taking preventive measures, such as vaccination, remain crucial. For weekly updates on respiratory virus activity, including influenza, COVID-19, and RSV, visit the Canadian respiratory virus surveillance dashboard.
Rising Influenza Cases in Canada: Expert Insights on the Epidemic’s Trajectory and Prevention
As Canada enters the influenza season, the latest Canadian Respiratory Virus Surveillance Report reveals a concerning uptick in cases, with a weekly hospitalization rate of 2.9 per 100,000 population. To better understand the situation,we spoke with dr. Emily Carter, an infectious disease specialist and epidemiologist at McGill University, who shared her insights on the current state of the epidemic, its potential trajectory, and the importance of vaccination. Here’s what she had to say.
The Start of the Influenza Epidemic
Senior Editor: dr.Carter, the report indicates that Canada has officially entered the influenza epidemic phase. Can you explain what this means and why it’s notable?
Dr. Emily Carter: Absolutely. The epidemic threshold is defined as 5% of positive influenza tests coupled with at least 15 weekly detections. This threshold was exceeded in the week ending December 21, marking the official start of the season. Currently, we’re seeing 11.3% of tests come back positive nationally, with Quebec slightly lower at 10.9%. This means the virus is circulating widely, and we’re still in the early stages of the epidemic. The numbers are likely to climb in the coming weeks.
The Ascending Phase of the Epidemic
Senior Editor: You’ve mentioned that we’re in the “ascending phase” of the epidemic. What dose this phase entail, and how long might it last?
Dr. Emily Carter: The ascending phase is when we see a steady increase in cases,hospitalizations,and positive test rates. Typically, an influenza season lasts between 10 to 16 weeks, and we’re far from the peak.Based on current trends, I expect the next few weeks to be especially challenging, with higher infection rates and more severe cases, especially among vulnerable populations.
High-Risk Populations and Complications
Senior Editor: Who is most at risk during this phase, and what kind of complications should we be aware of?
Dr. Emily Carter: Children under 5, particularly those under 2, and older adults, especially those 75 and over, are at the highest risk of severe illness and hospitalization. Influenza can lead to complications like pneumonia, worsening of chronic conditions, and even death in these groups. It’s crucial for caregivers and family members to be vigilant and take preventive measures to protect these individuals.
The Role of Vaccination
Senior Editor: with cases on the rise, is it still worth getting vaccinated? How effective is the vaccine this season?
Dr. Emily Carter: It’s absolutely not too late to get vaccinated. Protective antibodies develop within 7 to 14 days after vaccination, and since we’re still in the ascending phase, getting vaccinated now can provide protection during the peak of the season. On average, the vaccine reduces the risk of hospitalization by 50%. While effectiveness varies each year, vaccination remains one of the best tools we have to mitigate the impact of influenza.
Looking Ahead: What to Expect
Senior Editor: What can Canadians expect in the coming weeks, and what steps should they take to stay safe?
Dr. Emily Carter: We’re likely to see a continued rise in cases, hospitalizations, and positive test rates. I strongly encourage everyone,especially those in high-risk groups,to get vaccinated,practise good hand hygiene,and avoid close contact with individuals showing flu-like symptoms. Staying informed through resources like the Canadian Respiratory Virus Surveillance Dashboard is also key to understanding the evolving situation.
Key Insights at a glance
| Key Metric | Data |
|---|---|
| Weekly hospitalization rate | 2.9 per 100,000 population |
| Positive influenza tests in Canada | 11.3% |
| Positive influenza tests in Quebec | 10.9% |
| Average vaccine effectiveness | 50% |
As the influenza season progresses, staying informed and taking preventive measures, such as vaccination, remain crucial. For weekly updates on respiratory virus activity, including influenza, COVID-19, and RSV, visit the Canadian Respiratory Virus surveillance Dashboard.
