Here's why you should get all your vaccines as soon as possible, according to an expert

ACVS pharmacist prepares to administer a shot of Comirnaty, the new Pfizer/BioNTech vaccination booster for COVID-19. (Joe Burbank/Orlando Sentinel via AP)

The transition from summer to fall signals the start of school, cooling weather and, unfortunately, the beginning of flu season.

Health Canada and the World Health Organization recommend getting a flu shot every year, as flu viruses learn to evolve and the effectiveness of a shot decreases over time. But following the COVID-19 pandemic, vaccines have also been created to fight against the infectious disease, with new variants of the novel coronavirus requiring updated shots through the years.

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Earlier this month, Health Canada ordered the remaining COVID-19 vaccines to be destroyed in favour of the new Moderna vaccine, which should become available sometime this week.

And just this week, Ontario and Quebec also announced a newly approved respiratory syncytial virus (RSV) shot would be available for newborns, young children, pregnant women and those over 65 years of age, which is expected to reduce the amount of infants and elderly people in hospitals.

With all these shots, some Canadians may have questions about the benefit of each vaccine, whether they should get every shot and how often to get them, and if it's safe to get them all at once or if they should space them out. CTVNews.ca spoke with an infectious disease specialist to see what they suggest as we officially enter flu season.

Getting your shots

Jeffrey Pernica is an associate professor with McMaster University's department of pediatrics, specializing in infectious diseases for children. Part of his research includes seeing children who are hospitalized with disease, their diagnoses and the managing of those infections.

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"Many of these respiratory viruses tend to have stereotyped circulation patterns, and a lot of them come up in the winter," Pernica said. "The issues with the kind of influenza vaccines that we have is that they do not lead to long-term protection in these specific strains of influenza."

He adds that for the most at-risk populations, especially elderly Canadians, the protection from a single vaccine doesn't last very long, so he expects the COVID-19 shot to be a yearly thing.

Pharmacist Kim Nguyen administers a Moderna Spikevax COVID-19 vaccine at a CVS, Wednesday, Sept. 20, 2023, in Cypress, Texas. (Melissa Phillip/Houston Chronicle via AP)

As for RSV, Pernica says it likely won't be an annual shot, but the Canadian National Advisory Committee on Immunization recommends everyone 75 years or older get it, preferably in the fall before cases start to rise. In addition to seniors, RSV takes a toll on infants and young children.

"RSV is the worst respiratory pathogen affecting children," Pernica said, adding that one strategy for medical professionals is immunizing pregnant adults late in their pregnancy with the RSV vaccine so the baby an immune response and develops antibodies, similar to how the whooping cough vaccine is sometimes used.

Multiple vaccines at once

Despite claims about how it's unsafe or less effective to get multiple vaccines at once, Pernica says this is untrue, and sometimes there are compelling reasons to get multiple shots on the same day.

"More often than not, there are lots of people who need an influenza vaccine in the fall. There are lots of people who need a COVID-19 vaccine in the fall, and now there's even more people who need an RSV vaccine in the fall," he said. "At a practical level, it's often much better to get them all simultaneously."

Both Health Canada and the U.S. National Center for Immunization and Respiratory Diseases, a division of the U.S. Centers for Disease Control and Prevention (CDC), say it's perfectly fine to get all your vaccines at once.

Vaccine hesitancy

Since the rollout of vaccines through the COVID-19 pandemic, hesitancy towards getting shots has grown rapidly in Canada.

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Because of this, doctors like Pernica can have a difficult time explaining to patients and parents of younger patients why it's critical for them to get their updated shots when due.

"Vaccine hesitancy is a real issue because vaccines are the cheapest, yet most effective medical interventions that exist," he said. "The bedrock of trying to deal with this is really just talking to people, listening to what they have to say."

Pernica adds that the key to people getting their shots is making sure they have all the information they need to make a decision, especially when it comes to the RSV vaccine.

"While COVID-19 is devastatingly bad for older people, RSV is that for children. I would emphasize to all physicians, all families, all health-care stakeholders that RSV is bad to get in early infancy, and we now have a therapy that is very, very effective."