Nov 9, 2021

It’s especially important to get a flu shot this year: U of T infectious disease expert Susy Hota

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The University of Toronto is encouraging students, staff, faculty and librarians on its three campuses to get their annual flu shot to further protect their health during the COVID-19 pandemic.

Last year’s flu season was unusually mild due to COVID-19 lockdowns and other public health measures that reduced transmission. But with fewer public health measures in place this year, infectious disease experts say more people could get the flu, increasing their risk of severe illness should they contract both viruses.

Dr. Susy Hota

A high number of flu cases could also place an added strain on a health-care system that’s already under significant pressure, says Susy Hota, the medical director of infection prevention and control at the University Health Network and an associate professor in the Temerty Faculty of Medicine’s department of medicine.

The province makes the flu vaccine available for free to people six months of age and older who live, work or attend school in Ontario. U of T community members can obtain a flu shot at their local pharmacy or visit a Toronto Public Health clinic, where appointments can be booked in advance. There also are plans to offer flu shots at the Discovery Pharmacy on the St. George campus, while those with OHIP cards may be able to get the flu vaccine at their doctor’s office. U of T Mississauga’s Health & Counselling Centre also has information about flu shots.

More information on flu shots can be found at U of T’s UTogether website.

U of T News recently spoke with Hota about the flu shot and why it’s especially important this year.

Why is so important to get the flu shot while we’re still dealing with COVID-19?

We don’t yet know how COVID-19 and influenza will interact. Will people get sicker if they are co-infected with the two? The good news is that a small amount of data out of England showed that co-infections are uncommon. The bad news is that the risk of death with co-infections was higher than if you had a single infection.

During the last flu season, public health measures such as social distancing and masking resulted in little influenza transmission in many parts of the world. A big concern this year is what will happen with a more open society, and with fewer non-pharmacologic interventions in place. Will we see a more severe flu season?

The other important point is the health-care system. We’re still dealing with the pandemic, and health-care capacity is strained. If we also have to deal with a deluge of influenza infections, then this will strain the health-care system even further and make it hard for us to provide care for everyone who needs it.

How serious is the flu on its own?

Although most people don’t get severely ill or require hospitalization, complications from influenza infection can range from mild to serious. In older people, influenza infection can precipitate a heart attack or congestive heart failure. We also see secondary bacterial pneumonia that requires hospitalization. Bronchitis can be exacerbated. The influenza vaccine provides 40 to 60 per cent protection against the virus, so it’s a moderately effective vaccine. Our goal with vaccinations is to reduce these potential harms.

What about younger people?

There are age-related risk factors if you’re over the age of 65, but also if you’re under the age of two. However, younger people between those ages can also be at risk – if you’re pregnant, for example, or if you have health conditions such as chronic lung disease or asthma, heart disease, neurological problems or a compromised immune system. People who are obese, and people from certain backgrounds such as Indigenous Peoples can also suffer from poor outcomes due to influenza. The bottom line is we have readily available, fully funded vaccines in Ontario. This is why we recommend that everyone get a flu shot every year.

When should people get their flu shots?

Now. Influenza vaccination campaigns are rolled out in advance of the flu season, which runs from November to March or April. It also makes sense to protect yourself now because it’s getting colder and we’re spending more time inside.

What are the most common side effects of the flu shot?

Side effects are common to many vaccines. You can get local side effects or systemic side effects. The local ones are usually more common – up to 10 per cent of people will get swelling, pain, tenderness and maybe some redness at the injection site. The systemic ones are fever, chills, muscle aches and tiredness, which are signs that your immune cells are doing what they need to do.

What should someone do if they develop symptoms, but can’t tell if it’s COVID-19 or the flu?

Fever, cough and shortness of breath can be present in either a COVID-19 infection or influenza. Sore throat is less common with COVID-19, but we do see it. Runny nose, headache and muscle aches can be present in either. A loss of – or change in – your sense of smell or taste is more specific to COVID-19. Influenza tends to come on quite suddenly. COVID-19 can be more insidious.

Bottom line: COVID-19 is the one with the major public health implications. If you develop any of these symptoms, you need to stay home, and you should get tested for COVID-19. (We don't typically test people for influenza or other viruses unless they are hospitalized.) If you’re not working from home, check with your organization’s occupational health office, or with management, about clearance for when you can come back.

Do we have a sense yet of how severe this year’s flu strain may be?

Severity is not necessarily specific to a strain. There are subtypes of influenza. Influenza A and B are the types that most commonly cause infections in humans leading to symptoms and hospitalizations. The H3N2 subtype of influenza A more often affects older people and can more often lead to complications and hospitalizations. H1N1, which caused the 2009-10 pandemic, more often affects younger adults and, for that reason, causes fewer hospitalizations. Influenza B more often affects children and older adults. Globally, what we’re seeing now is influenza B in Mexico and the Caribbean, but also some H3N2 in South Asia. So, it’s a little unclear what will happen here in North America.

Any last words of advice as we head into flu season?

Be vigilant about your health. Don't say “Oh, it’s just a cold.” Stay home, except to get tested for COVID-19.

Learn more about flu shots at UTogether