What do I need to know about this year's flu shot?

Experts say it's almost time to roll up your sleeve for the annual flu shot. 

But this year, some pharmacists say people have questions about the influenza vaccine rollout, which will coincide with the rollout of COVID-19 vaccines that target Omicron strains — also known as bivalent vaccines.

Ashley Davidson, a pharmacist and associate owner of Shoppers Drug Mart in St. Albert, Alta., has fielded a lot of questions.

"So many people are asking about flu shots and I think a lot of that conversation comes around how do they time their vaccines and what does that look like?" she told Dr. Brian Goldman, host of CBC's podcast The Dose. 

Here's what experts have to say about this year's flu vaccines. 

What do we know about the upcoming flu season?

The number of flu cases this year could look a little different than what we've seen over the last few years.

"What has changed in the last two years is we had historical lows throughout the pandemic and we've now been in the time of uncertainty about when is it going to come back, what is it going to look like," said Dr. Robyn Harrison, vice-chair of the National Advisory Committee on Immunization (NACI) and infectious disease specialist, on Wednesday during a webinar on seasonal influenza.

An example of what could come is Australia's recent flu season, which happens before Canada's because it is in the southern hemisphere.

The country recently had its worst season in years, with data from Australia's Department of Health and Aged Care showing influenza infections were higher than the five-year average and infections notably spiked, then dropped, earlier than usual. 

Canadians also haven't had much exposure to flu over the last couple of years because of mask mandates and other public health measures introduced during the pandemic, Davidson said.

"One thing that stands out to me this year is that we won't have masks in schools. So that is going to increase the potential exposure for flu virus for children as well," she said. 

According to experts, influenza is a serious illness. Up until 2019, it is estimated that there are on average 12,000 hospital stays in Canada due to influenza every year, and about 3,500 deaths each year are caused by the flu, Harrison said.

Influenza is very contagious and spreads by respiratory droplets which cause an infection. Symptoms can vary but commonly include fever, sore throat, runny nose, cough, fatigue and muscle aches.

Who is eligible for a flu shot?

Experts say it's important to get a flu shot each year as vaccine-induced immunity does wane over time. 

There are three types of influenza vaccines approved in Canada, according to NACI:

• Inactivated influenza vaccine
• Recombinant influenza vaccines
• Live attenuated influenza vaccine

Anyone six months of age or older who does not have a known negative reaction to the vaccine should get a flu shot every year. 

"The reason why children under six months of age are not included in that is because we know that they don't mount a good immune response to influenza vaccines," said Dr. Jesse Papenburg, a pediatric infectious disease and medical microbiology specialist, during Wednesday's webinar. He is also the chair of the NACI influenza working group. 

He said the suggested flu shot schedule for children nine and older and adults is one dose of the influenza vaccine at the beginning of flu season. 

For kids aged six months to eight years who have yet to receive a flu shot, NACI recommends two doses given at least four weeks apart. 

Who shouldn't get a flu shot?

Papenburg said NACI recommendations for those who shouldn't get any of the flu shots include:

• People who have had an anaphylactic reaction to any of the vaccine's components, except for eggs.
• People who have developed Guillain-Barré syndrome (GBS) within six weeks of a previous flu vaccine (unless another cause has been found).
• Infants under six months of age.

NACI's recommendations on who shouldn't get the live attenuated influenza vaccine can be found here. 

When should I get a flu shot?

Davidson recommends that people get the influenza vaccine as soon as it's available.

Canada's flu season typically lasts from mid-October to April or early May, Davidson said. 

"I will often remind patients that although you can get your flu shot right away, it does take about two weeks to develop an immune response to that vaccination," she said. 

"It is important to get your shot as soon as you can to ensure that you have coverage through the flu season."

Can I get a flu shot and a COVID-19 vaccine at the same time?

For most people, the short answer is yes.

For people age five and older, all seasonal influenza vaccines, including the live-attenuated influenza vaccine, may be given at the same time or before or after other vaccines, including COVID-19 vaccines, according to the most recent recommendations from NACI.  

"It is important that you're protected from both viruses throughout the winter," said Davidson. 

WATCH | Experts break down what to expect from flu season this year: 

However, kids aged six months to five years shouldn't receive a COVID-19 vaccine and an influenza shot at the same time, according to NACI, which instead recommends those in this age group wait 14 days between COVID-19 shots and other vaccines.

It's a precautionary approach "to prevent erroneous attribution of adverse events following immunization to one particular vaccine or the other," reads the committee's advice. 

How effective are flu vaccines this year?

Experts say influenza vaccines have been proven to help prevent influenza, transmission, complications and hospitalizations. 

The effectiveness of flu vaccines can vary year-to-year because it all depends on the strains circulating, Davidson and Harrison said. 

For the 2004-2005 flu season to 2019-20, Harrison said the effectiveness of influenza vaccines in Canada has varied between around 40 to 70 per cent. 

Every year, World Health Organization (WHO) experts make recommendations on which strains of the influenza virus should be targeted by the vaccines. 

This year, WHO recommended three influenza strains — one influenza A (H1N1); one influenza A (H3N2) and one influenza B — for inclusion in the trivalent flu shot. 

Although the flu vaccine's effectiveness can vary, both Harrison and Davidson agree that it does offer protection. 

"The effectiveness of the vaccine may not be 100 per cent and may not persist beyond a year, but has impact and that's why it's recommended," Harrison said.

Written and produced by Stephanie Dubois