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influenza (flu)

influenza in canada: stats, impact and resources

every year, about five to 10 per cent of adults and 20 to 30 per cent of children in canada are infected with the flu.

by karen hawthorne

published sep 26, 2024

10 minute read

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10 minute read

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research data reviewed by immunologists at johns hopkins university found that women typically experience greater morbidity and mortality during influenza outbreaks and pandemics. getty images

influenza, more commonly known as flu, is a contagious respiratory illness caused by influenza viruses that infect the nose, throat and sometimes the lungs. as most of us have experienced, flu can cause mild symptoms like fever, body aches and chills, runny nose, headache and vomiting (more frequent in children) that sideline our regular routine. but it can also bring on severe illness, and at times can lead to death. this can be the case for healthy people and for those who are more vulnerable to infection because of a chronic illness or weakened immunity. in other words, flu is not something to trivialize, especially in the fall and winter when it circulates more because we’re spending more time indoors closer to others. all it takes to spread is for you to breathe in airborne droplets from coughs and sneezes of someone who is infected or touch a surface with the virus and then touch your nose, eyes or mouth.

what can compound the burden of flu season on healthcare services and the threat to individuals, are other prevalent viruses like respiratory syncytial virus, or rsv, and covid-19.

“that’s what’s really changed in the last four years is now we have another very powerful, very impactful virus, covid-19, that’s co-circulating with these other respiratory viruses, and it doesn’t necessarily peak at the same time, but it can,” says dr. susy hota, an infectious disease expert at the university health network’s toronto general hospital research institute.

“if you have a covid peak followed by an influenza and other respiratory virus peak, what that means is you have a more prolonged period of strain within the healthcare system and of people getting sick. if they happen to peak at the same time, then you have a different problem that’s equally difficult, which is an even larger peak of people who are requiring help and who get really sick at the same time.”

co-infections of flu and covid, for example, can occur at any age, posing a danger particularly to older people and others with weaker immune systems. and you really don’t want that, as research has shown that co-infections can be more serious then just getting sick with one virus at a time.

influenza stats in canada

every year, about five to 10 per cent of adults and 20 to 30 per cent of children in canada are infected with the flu. the pandemic shutdown saw flu infection rates drop, but the return to “normal life” of in-person work, school, social gatherings and activities has seen an uptick in the virus as expected.

people also are turning to their healthcare providers for diagnosis and care – which is always recommended if symptoms are severe or persist, notes hota.

“you should be going to the emergency department if you are having trouble breathing, if you’re getting chest pains, if you’re feeling dizzy or you can’t get up and walk. if you have symptoms like these that indicate that you’re more severely ill from it, or if you are known to be at risk for severe complications of a respiratory virus infection.”

the vast majority of people who are not at risk for complications or not severely ill from the infection just need supportive care, she adds, “which means you go home, you take care of yourself. rest, plenty of fluids, stay away from other people so you don’t pass it on and you will recover in seven to 10 days.”

the 2022 to 2023 flu season was intense but relatively brief, reports the public health agency of canada. there were 74,344 laboratory-confirmed influenza detections out of 1,188,962 total laboratory tests. this is the most detection, and the most tests ever recorded in one season. before the pandemic, we saw an average of 276,592 tests and 47,018 detections from 2014 to 2015 through to the 2018 to 2019 flu season.

statistics from the 2022 to 2023 season also note the following:

4,216 influenza-associated hospitalizations were reported by participating provinces and territories
most hospitalizations were associated with influenza a (97 per cent)
the highest cumulative hospitalization rates were among children aged 0 to four years (131 per 100,000 population) and adults aged 65 years and older (131 per 100,000 population)

flu is also a common cause of pneumonia, a serious lung infection, especially in younger children, the elderly, pregnant women, or people with chronic health conditions or who live in a nursing home. most cases of flu don’t lead to pneumonia, but when it happens, cases can be more severe and deadly.

in fact, flu and pneumonia are ranked among the top 10 leading causes of death in canada, notes infection prevention and control canada. estimates suggest that influenza causes approximately 12,200 hospitalizations and 3,500 deaths each year.

in 2022, there were 15.4 deaths from flu and pneumonia in canada per 100,000 population.

also, research data reviewed by immunologists at johns hopkins university found that women are impacted differently than men:

women typically experience greater morbidity and mortality during influenza outbreaks and pandemics
women are less likely to accept vaccines
women develop higher immunity and greater protection following vaccination

the mechanisms behind the differences are attributed to immunological, hormonal, behavioural and genetic factors.

in terms of prevention, flu vaccination is the gold standard, but we’re still not where we should be in uptake. vaccination rates from the 2022 to 2023 flu season reveal:

only 43 per cent of adults aged 18 to 64 with chronic medical conditions were vaccinated
74 per cent of seniors were vaccinated, which is closer to the coverage goal of 80 per cent but doesn’t reflect significant improvement
21 per cent of people cited the most common reason for not getting the flu vaccine as just not getting around to it

a new flu vaccine is produced every year as a result, based on recommendations of circulating flu strains by the world health organization, making it critical to get the flu shot every year. flu viruses can change and the effectiveness of the flu shot can decrease over time.

the national advisory committee on immunization, or naci, an advisory body to the public health agency of canada, makes recommendations on the optimal use of vaccines available in canada and issues a statement each year. naci recommends an influenza vaccine for all people in canada aged six months and older who do not have contraindications to the vaccine. the flu vaccine is publicly funded and available across canada.

what coming in the 2024 to 2025 season?

“there’s nothing that i’ve seen yet that’s indicating we may be heading into a worse season than last year,” notes nota. “i say this with a lot of restraint because influenza can surprise you. it’s very difficult to predict exactly what each year is going to be like. but so far it doesn’t appear like anything unusual has been happening. however, it still always has a big impact on the health system every year. so the vaccination piece is really important.”

instances of severe adverse reactions are uncommon, and the centers for disease control and prevention has found there is no association between vaccinations and an increased risk of death at the population level. research has also shown that individuals who became infected with the flu despite vaccination were 26 per cent less likely to end up in the icu and had a 31 per cent reduced risk of death.

basic prevention measures are also highly recommended, as infection prevention and control canada outlines the following:

good hand hygiene practices, such as handwashing or use of an alcohol-based hand rub after contact with the eyes, mouth, nose or secretions
avoid handling soiled tissues or objects used by an ill person
cover coughs and sneezes
ill persons should stay at home

as hota adds, “it’s always important to be paying attention to your symptoms. if you are sick, be considerate to others and stay home” to prevent the spread of infection. “as well, if you’re feeling sick and you do have to go out, then wear a mask.”

impact of influenza on canadian society

when you look at the sheer number of people affected by flu, you get a sense of the impact on individuals, for one, and the cost to healthcare services. when kids get sick, family caregivers may need time off work. when employees get sick, absenteeism at workplaces soars, especially during flu season. the conference board of canada estimates that employee absenteeism costs the canadian economy more than $16 billion annually. this figure includes both direct costs of wages paid to absent employees and indirect costs of lost productivity and replacement worker costs.

then consider the impact on healthcare with hospitalizations related to flu. the canadian public health association cites costs from a 2017 study:

each case of influenza that resulted in hospitalization ended up costing the health care system between $14,000 and $20,000
with an estimated 12,000 influenza hospitalizations each year, the cost to the canadian economy is between $168 and $240 million

again, vaccination is critical to reducing the impact. in 2016, the federal government committed $25 million to increase and maintain vaccination coverage by creating the immunization partnership fund, earmarking $3 to $5 million dollars in funding per year for five years to 2021. then covid-19 hit. an additional $54 million over three years, 2020 to 2023, was added to support community-based efforts to reduce vaccine preventable diseases and address vaccine misinformation and disinformation. further dollars were invested to expand efforts beyond covid-19 to flu and other infection, with $9.5 million for 2023 to 2024, followed by $20 million for 2023 to 2026 to further efforts to strengthen vaccine confidence and reduce barriers to vaccination, particularly among priority populations.

further, canadian researchers surveyed canadian adults 50 years and older in august 2019 and may 2020 to look at the impact of flu on their ability to work, volunteer and provide care (for kids or aging parents).

“in comparing older vs. younger respondents, we found that the impact on life responsibilities and activities was fairly similar,” the authors note. “however, having influenza was more likely to result in absenteeism from work and caregiving for the 50 to 64 year adults than the older age group. this highlights the importance of targeted messaging about influenza prevention, including through vaccination, to adults 50 years and older who may not see themselves at risk of the daily impact from influenza.”

they also recognized a reduction in people’s ability to provide care for up to two full weeks when they were trying to recover from flu. caregivers, unlike people who work or volunteer, may not have the option of pulling back on care duties when they’re ill. the study revealed a significant proportion of caregivers who continued to provide care did while recovering but were functioning at less capacity – a finding particularly true for those 65 years and older. caring for dependents while you’re ill has many consequences, the authors say, both in terms of prolonging recovery and placing others at risk for the virus.

resources and support for influenza in canada

where can people go for help and support? flu clinics across canada provide information about the flu and vaccination, and pharmacists offer counselling, which has become critically important for people who don’t have a family doctor.

there are also telehealth services that are readily available. ontarians can call 811 (formerly telehealth) or chat online with a registered nurse to get health information, including help with flu to manage symptoms. visit health connect ontario to access the chat service. residents in all other provinces and territories can also call 811 to connect with a nurse in the case of a non-urgent health issue.

infection prevention and control canada has a list of resource links for canadians.

hota stresses the importance of vaccination and everyday prevention measures. in the bigger picture, she is concerned about the h5n1 avian flu outbreaks that are happening in dairy cattle in the u.s. “which is the first time this has ever been seen,” she says of the virus that has been percolating widespread in poultry farms in canada as well.

the cattle issue hasn’t come to canada yet, but there are global cases now in people who work at these farms. “h5n1 is a totally new type of influenza to humans, so we don’t have immunity to that type of influenza and we don’t want it to continue to spread amongst humans because that could start a pandemic. we are familiar with the word pandemic, and we do not like it.”

how likely is this scenario? hota points out that it’s very possible for someone to get infected with two different forms of flu virus at the same time. you can get a common seasonal strain of influenza, and if you’re so unlucky, you can also get h5n1 because it enters our population in canada. this provides an opportunity for those two viruses inside your body to start to connect with one another, exchange genetic material and adapt to become more efficient at going from person to person.

“if we can prevent people from getting infected with the seasonal strains because we have those tools in our pocket right now, then it would discourage these events from happening. you can’t prevent it entirely, but it would discourage it.”

karen hawthorne

karen hawthorne worked for six years as a digital editor for the national post, contributing articles on health, business, culture and travel for affiliated newspapers across canada. she now writes from her home office in toronto and takes breaks to bounce with her son on the backyard trampoline and walk bingo, her bull terrier.

influenza in canada: stats, impact and resources

every year, about five to 10 per cent of adults and 20 to 30 per cent of children in canada are infected with the flu.

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