Now that the weather is getting cooler and the flu season is warming up, medical experts are reminding Canadians to get the flu shot to protect themselves and their loved ones.
Canada's elderly and young children are particularly at risk as multiple strains of influenza circulate and hospitalizations begin to rise in parts of the country.
Health experts are urging Canadians to get vaccinated, even if the strain in the flu vaccine doesn't exactly match the circulating strain, as the shot provides the best protection.
“Some people mistake the flu for a mild cough, cold or sniffle, but that's not the case. Influenza is a very serious virus that kills about 350,000 to 500,000 people a year around the world, and it's likely to kill Canadians, too,” says Dr. Isaac Bogoch, an infectious disease specialist at Toronto General Hospital.
“By getting the flu vaccine, you can take steps to reduce your risk of getting the flu.”
According to Health Canada, most people who get the flu begin to develop symptoms within one to four days.
Symptoms include fever, cough, muscle aches and pains, chills, fatigue, headache, sore throat, loss of appetite, and runny or stuffy nose. In some people (mainly children), diarrhea, nausea, and vomiting may also occur.
Health Canada says these conditions can worsen chronic health conditions and lead to more serious complications that can lead to heart complications, pneumonia, respiratory failure, hospitalization and even death.
Bogoch said influenza viruses are constantly evolving, but one thing that remains constant is that the number of infections and hospitalizations increases at about the same time every year.
“As expected, we're going to see an increase in these viruses over the fall and winter, and that's exactly what's happening right now. There's nothing really new from an epidemiological standpoint, from a clinical standpoint, and from a standpoint of how to protect ourselves at the individual and community level,” Bogoch said.
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“But I think it's a good reminder to talk about it and remind ourselves of the tools that are available to us.”
How long is flu season now?
Health Canada statistics show that as of Nov. 7, nearly 2 per cent of all tests in Canada were positive for influenza, which experts believe is relatively low.
However, the proportion is increasing.
“Nationally, indicators of influenza activity remain at interseasonal levels but have increased in recent weeks,” Health Canada said on its website, adding that the number of reported outbreaks and weekly hospitalizations also appear to be low.
Medical experts say these numbers can change quickly, and a warning sign could be that more children are becoming infected first.
“Overall, the positivity rate is still low at about 2% nationally, but the positivity rate among school-age children in Ontario and Quebec is over 5%, 7%, and in some groups over 10%,” said Dr. Jesse Papenberg, a pediatric infectious disease specialist at the Montreal Children's Hospital at McGill University Health Centre.
“So we're seeing influenza transmission among school-age children, and this group is often the first to become infected, and that's when community transmission really starts to increase.”
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A survey study earlier this year found that 72 per cent of Canadians think child vaccinations should “probably” or “definitely” be mandatory, but this trend has declined since the pandemic.
The same survey found that 88% supported a similar mandate in 2018.
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According to Health Canada data, the number of influenza cases reported in Canada is primarily among people 65 and older, who are also the main age group presenting to hospitals with the flu.
Children under the age of four are the second most common age group for influenza-related hospitalizations, according to the latest government report.
Is this influenza vaccination effective?
According to Health Canada, three strains of the influenza virus are currently circulating. There are two types of influenza A, known as H1N1 and H3N2, and influenza B.
The flu vaccine currently available to all Canadians is designed to protect individuals against all three strains, and Health Canada cites research showing that the vaccine's ability to match one of the strains may be slightly “reduced” compared to the other two.
“At the end of the southern hemisphere influenza season, H3N2 strains with some mutations started to emerge, suggesting that vaccines might not be as effective against this strain,” Papenburg said.
“We don't really know in the field how effective this vaccine is against that strain, but it's probably going to have some effect. We also don't know yet whether this season will be an H1N1 season or an H3N2 season. It's still too early to tell and there's a lot of uncertainty.”
Medical experts say vaccines aren't perfect, but it's still better than nothing.
“There are three viruses that are circulating. We have some protection against two and some protection against the third. I would always give some protection over no protection, especially with the flu,” Bogoch said.
“This year, one of those three elements could be a little bit mismatched. That doesn't mean it won't work, it just means that one of those three elements might be less effective.”
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