Can you still get sick if you’re vaccinated?

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Outbreaks of vaccine-preventable diseases in Canada are on the rise, and there may be a slim chance you can still become infected — even if you have all of your shots.

According to Dr. Karina Top, pediatric infectious disease specialist and investigator at the Canadian Center for Vaccinology, no vaccine is 100 per cent effective in every single person (though effectiveness depends on the vaccine).

For example, “the vaccine for measles… we know about 95 per cent of people will respond to the vaccine, but that leaves five per cent who don’t,” said Top. “We recommend a second dose of the Measles, Mumps, Rubella (MMR) vaccine to catch the people that didn’t respond [fully] to the first dose. That’s why, in Canada, we recommend two doses.”

READ MORE: Unvaccinated: How ‘vaccine hesitancy’ became a threat to public health

For Top, the issue of effectiveness is even more of a reason to be vaccinated.

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“For anyone, child or adult, if you’ve been vaccinated and you still get infected, [you’re] going to be much less sick than if you haven’t had the vaccine at all,” she said. “You’re much less likely to end up in hospital.”

Ninety-nine out of 100 people who have had two doses should be immune to measles, mumps and rubella, Top said, but that does leave one person for whom the vaccine may not completely work.

“That’s why we want everyone who can get vaccinated to get vaccinated — so we can protect that one person.”

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This is known as herd-immunity protection, which happens when enough of a population is immunized against a disease for those unable to be immunized (like a newborn infant) to be protected. For a disease like pertussis, a 94 per cent immunization rate is required, for example.

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Health officials have identified a number of places across the country that are vulnerable to outbreaks because they have low “herd-immunity” rates. According to a 2014 Alberta Health Services presentation, those communities included Norwich (Oxford County), St. Catharines and Brantford in Ontario; the Lower Fraser Valley, Smithers and Vanderhoof in B.C.; and the Lacombe, Rimbey, Red Deer and Lethbridge areas in Alberta.

Dr. Sarah Wilson, a public health physician with Public Health Ontario, echoes Top’s advice.

“The important point to remember is that, when we do see cases among people who have been vaccinated, they tend to be less severe in terms of complications [from] the disease, the severity, how long the symptoms last [and] risk of hospitalization,” said Wilson.

READ MORE: Unvaccinated: Pockets of Canada vulnerable to serious outbreaks of disease

There are very few reasons why someone may not be able to be vaccinated.

Those with a weak immune system should not receive any vaccination containing a live virus, such as the MMR vaccine. “But other vaccines, like the tetanus vaccine… even someone with a low immune system can get this” because it doesn’t contain a live virus, said Top.

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According to Public Health Canada’s immunization schedule, newborn babies are also unable to receive most vaccines until at least two months of age, though that regulation varies across provinces and territories, so it’s best to consult with your doctor about the best vaccination plan for you and your family.

Here are some other ways to ensure you’re as protected as much as possible.

Know that vaccination recommendations change over time

It’s important you know what vaccines you received — and when — because public health recommendations can change, meaning you might be due for an upgrade well into adulthood.

“It was only in 1996 that Canadian provinces began recommending a two-dose MMR vaccine,” Top said. This means people who were in elementary school prior to 1996 may have only received one dose, possibly leaving them vulnerable to measles, mumps or rubella.

“We also recommend that adults get a tetanus booster every 10 years,” said Top. The guidelines will differ across provinces and across diseases.

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“We often talk about [the effectiveness] of vaccines in general, but this varies by vaccine,” said Wilson.
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“For example, the MMR vaccine is almost 100 per cent effective after two doses… but we know that there are other vaccines, such as pertussis-containing vaccines (which prevents whooping cough), that require multiple doses.”

“That’s why our immunization schedule looks different for different vaccines. It’s not just one approach for all diseases,” Wilson said.

Keep track of your immunization record

While some provinces have vaccination databases, others don’t. That’s why it’s best you keep a record of what you’ve been administered.

“As people move around between doctors and provinces, it’s the best way to have an accurate record of what you have,” said Top.

“The best thing for everyone to do is check their vaccine status and look up their immunization records,” said Top. This could involve contacting your family physician, the public health officials in the area where you attended elementary school or your provincial public health organization.

READ MORE: ‘An extremely contagious disease’: Confirmed measles case is Calgary’s second in a month, AHS says

According to Wilson, tracking your own immunizations is crucial as vaccines are increasingly offered by providers outside of your own family practitioner (such as by pharmacists).

“It’s important for [vaccines] to be convenient, but it’s a challenge to have immunization records [as a result],” said Wilson.
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Wilson recommends the CANImmunize app, which provides a secure digital location for you to track vaccinations for your entire family. It also sends reminders for when you’re due to receive another vaccine and provides information about immunization schedules in your province or territory.

Get you — and your children — vaccinated

According to exclusive Ipsos polling conducted for Global News, two-thirds of parents believe vaccinations are necessary but one in three still worry about side effects and while 85 per cent of parents surveyed say they believe vaccinations are safe, 85 per cent also feel there is a lot of misinformation out there.

“The group of individuals that are the hardcore anti-vaxxers is actually relatively small. You’re looking at two to five per cent, depending on how you count it,” said Dr. Timothy Caulfield, the research director of the Health Law Institute at the University of Alberta.

Still, confusion persists largely because “those who are spreading misinformation are absolutely brilliant at amplifying that false information using emotionally charged, media-savvy techniques,” said Dr. Theresa Tam, chief public health officer of Canada.

Many people opt not to vaccinate, too, because of religious or cultural practices.

Regardless, Top says the best way to protect yourself and your family is to speak to your doctor about what vaccinations are recommended and at what ages.

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“The best way to protect your health is for everyone to get all the recommended vaccines… Even for the small number of people who get the vaccines and still get sick, they’re a lot less sick than they would’ve been had they not had the vaccines.”

— With files from Jeff Semple and Heather Yourex-West

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