Measles outbreak: 5 questions and answers

WATCH ABOVE: Health reporter Carmen Chai looks at the contentious issue of vaccinations and what you need to know about the measles, mumps, rubella vaccine.

TORONTO – Measles outbreaks in Canada and the United States has vaccination on most parents’ minds.

Health officials are concerned about a growing anti-vaccination movement, misconceptions about the vaccine and the virus’ contagiousness.

Here are answers to some questions about why some vaccinated people still ended up infected, why parents are refusing the vaccine and how to tell if your child is immune.

How did some people get the measles if they were vaccinated?

The number of measles cases is growing in Toronto and one of the confirmed cases includes a patient who was fully vaccinated. Meanwhile, the measles outbreak stemming from Disneyland in the United States also included a duo of patients who received their two measles shots.

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READ MORE: Toronto Public Health says 4 of 6 measles cases might be related

What happened? A few factors could be at play here, according to Jason Tetro, a Canadian microbiologist and author of The Germ Code.

For starters, these people could have received their two shots with a significant gap in between.

“We know that one dose of the vaccine has lower efficacy than two doses and if you get two doses fairly close together, you’ll have lifelong immunity,” he explained. If you spaced out your two shots, a booster could help.

“These are the types of things we’re still learning about when it comes to the vaccine booster,” he said.

READ MORE: What’s in a measles vaccine? 4 things you need to know

The Centers for Disease Control and Prevention says that “very few people” – to the tune of about three in 100 – who get two doses of the measles vaccine will still get measles if exposed to the virus.

“Experts aren’t sure why; it could be that their immune systems didn’t respond as well as they should have to the vaccine,” the CDC says on its website.

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But there is a silver lining: if you’re vaccinated and still catch the virus, you’ll have a milder case and you’re also less likely to spread the disease to other people.

Who is considered immune to measles?

There are three groups of people who are generally considered protected: those who received their two shots of the MMR vaccine (measles, mumps, rubella), if you have a laboratory confirm that you had measles at some point in your life, or if you were born before 1957, according to the CDC.

Public health officials suggest that if you were born at that time, you were likely exposed to the measles. If you didn’t catch the measles and you didn’t get the vaccine, you should get immunized though.

READ MORE: Why is measles so contagious? 5 things you need to know

If you’re not sure if you’ve been vaccinated, you should try to find your vaccination records or any documentation of measles immunity.

Another option is to have a doctor test your blood to determine if you’re immune, the CDC advises. You can also get another dose of the MMR vaccine – there’s no harm, it suggests.

Why are some parents refusing the measles vaccine?

This isn’t easy to answer. Google ‘anti-vaccination’ and you’ll enter the Wild West of medical debate. Some theories suggest there is a link between autism and vaccinating children. Others suggest the vaccine is toxic or contains heavy metals.

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READ MORE: Anti-vaccination movement means preventable diseases making a comeback

In 1998, a prestigious British medical journal published a study that tied the MMR vaccine to autism. The study was based on a small series of observations in just a dozen children. Ultimately, it was retracted but it left its mark: in the United Kingdom, there was a significant drop in immunization rates while American researchers say that up to 125,000 kids born in the late 1990s didn’t get vaccinated because of the report.

Celebrities, such as Jenny McCarthy and Alicia Silverstone among others, have also fueled the fire as they openly oppose vaccination.

READ MORE: How should health officials reverse an anti-vaxxer movement?

One aspect of the anti-vaccination movement is relying on herd immunity — if everyone else around you is vaccinated, why should you need the shot?

“The problem is over time, it brings back measles. These things are very cyclical where we may continue to see waning vaccination rates and then you’ll see resurgence of the disease, which will inevitably push up vaccination rates,” Dr. Michael Gardam, director of infection prevention and control at University Health Network, said.

But who really shouldn’t be getting the measles vaccine?

In Canada, the vaccination schedule looks like this: the first shot should be administered at 12 to 15 months of age, and again at the 18-month mark or at four to six years of age depending on your province or territory.

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The MMR vaccine shouldn’t be administered earlier because it may not be as effective. That also applies to babies and toddlers who aren’t at optimal health when it’s time for them to get their shot.

READ MORE: 6 vaccination myths debunked

“If you have any kind of compromised immune system, any kind of infection like a fever, you should talk with your doctor before you get the shot,” Tetro advised.

Pregnant women shouldn’t get the MMR vaccine because of a risk to their fetus. Instead, they should wait about 28 days after vaccination before conceiving, the CDC says.

READ MORE: Which Toronto schools have the lowest measles vaccination rates?

Finally, if you have egg allergies, consult with your doctor before getting the MMR vaccine. Because the viruses are grown in chick embryo cell cultures – like unhatched fertilized eggs – there’s a minute possibility of an allergic reaction.

It isn’t a major concern, but it’s worth asking your doctor, Tetro says.

Are there side effects?

There are worries that the vaccine can trigger illness or make you a vector for the disease. This isn’t the case, Tetro says.

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For starters, the viruses in the vaccine are attenuated, which means they can’t spread and they can’t reproduce. It’s unlikely you’d shed the virus.

“People who have been vaccinated and then become exposed to the virus may still get a low-level, mild infection if they don’t have full immunity but even these people don’t shed the virus,” Tetro explained.

READ MORE: Combined MMRV vaccine carries small risk of seizures, Canadian study warns

While your body is fighting the viruses from the vaccine, you could encounter minor side effects: an aching arm from the shot, inflammation as your immune system kicks into gear, or a stomach ache, as examples.

You could be susceptible to other infections, such as a cold, as your body focuses its efforts on fighting off the vaccine’s viruses.

– With a file from the Associated Press

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