Start of the influenza epidemic in Canada

The influenza – or flu – epidemic has officially started in Canada. It is too early to say whether this season will be marked by a significant number of infected people, but we know that the circulation of viruses will be very active in the coming weeks, since the peak of the epidemic has not yet been reached.

The Canadian respiratory virus surveillance report indicates that the weekly rate of influenza-related hospitalizations is 2.9 per 100,000 population.

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 thatcommented Dr. Jesse Papenburg, who works at the Montreal Children’s Hospital.

The epidemic threshold was exceeded the week ending December 21 in Canada. Since then, the curve of influenza infections has continued to rise. The epidemic threshold is 5% of positive tests for influenza. When it is exceeded and at least 15 weekly detections are reported, a seasonal flu epidemic is declared.

In Canada, the percentage of positive influenza tests in clinical laboratories is 11.3%; in Quebec, it is 10.9%, according to the most recent data from the National Institute of Public Health of Quebec (INSPQ).

Dr Papenburg, who is a pediatrician, infectious disease specialist and microbiologist, explains that we are in the ascending phase of the epidemic.

The season has started and in the coming weeks the incidence rates will continue to increase and we will see many more cases of influenza, he said. Usually, an influenza season can last 10 to 16 weeks, so we still have several weeks left and we are far from the peak.

Dr. Papenburg warns young children and the elderly who are at higher risk of complications. Children under 5 years old, and 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.he says.

Not too late for vaccination

I have the impression that we are going to see a typical influenza season which arrives in the middle of winter and which will cause serious illness, particularly in those at highest risk.continues Dr. Papenburg, who is also an associate member of the Department of Epidemiology, Biostatistics and Occupational Health and an assistant professor of pediatrics and the Faculty of Medicine at McGill University.

He reminds us that there is always time to get vaccinated against influenza. Protective antibodies develop 7 to 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 provide protection during the period when there is the greatest circulation of influenza.

Dr. Papenburg points out that although vaccine effectiveness varies from year to year, the average protection is 50%. In other words, getting vaccinated reduces the risk of hospitalization by half.

Influenza vaccine effectiveness estimates for the 2024-2025 season are expected to be available in February or March 2025.

Pressure on hospitals

As of Monday afternoon, more than 5,200 people were in emergency rooms across the province. The occupancy rate for all emergency departments in Quebec was 130%.

Currently, our emergency rooms are frequented by patients who have respiratory infectionsargued Dr. Papenburg. At the Montreal Children’s Hospital, where he works, he is seeing more and more hospitalizations for influenza, including cases in intensive care.

It is clear that at the moment influenza is causing a burden in outpatient clinics and emergency rooms, but also in terms of bed occupancy.

In addition to influenza and COVID-19, it’s respiratory syncytial virus (RSV) season. The data of theINSPQ indicate that 937 cases were reported for the week ending January 11.

The percentage of positive tests VRS however, seems to be on a downward slope in Quebec with a positivity rate of 9.5%. At the end of December, this percentage hovered around 13%.

From what we see, at the moment, in pediatrics, we are in the middle of the season of VRS. Among our young children under the age of one, many present with an infection in the VRStestifies Dr. Papenburg.

He points out that frequent hand washing reduces the risk of having a respiratory infection. If you have a fever or cough, public health recommends staying at home or wearing a mask if it is absolutely necessary to go to a public place.