What you need to know about the measles vaccine — from who should get it to how long immunity lasts

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In Canada, measles was a disease of the past. But setbacks in vaccination rates have allowed the virus to circulate again and now pose an increasing health threat.

Although Canada officially eliminated measles about 30 years ago, medical experts have long warned that measles is measles. ready to make a comeback And the movement may have been accelerated by the disruption of routine childhood immunization efforts during the coronavirus pandemic.

Health officials are on high alert as there are now tens of thousands of cases in Europe and nearly 100 recent cases in Canada and the United States.

Warnings about international travel, reminders to ensure families are up to date on measles vaccines, and another reminder that the virus is highly contagious and can cause pneumonia, brain inflammation and even death. there is.

“A lot of people are worried,” said Dr. Alikan Abdullah, a family physician in Ottawa. “Measles has not been present in our society for a long time.”

So how should Canadians deal with the latest guidance on measles vaccination? And who is actually protected? Are you ready to live?

Who should receive the measles vaccine?

If you or your child have any of the following symptoms: I never have If you have had the measles-mumps-rubella vaccine (MMR) and have never had measles, the official guidance is simple. “Let's get vaccinated.”

But after that it gets a little complicated.

For Canadian children, the common schedule is now two doses, both given before they start school. The first dose of her MMR should be given when the child is 12 to 15 months old, the second dose should be given when she is 18 months old or any time thereafter, but no later than preschool age. there is. Note Canada's Immunization Guide.

Even adults, if they were born rear Two doses of the MMR vaccine are now routinely given, and you probably received two doses as a child.

However, some adults may only take one dose. That includes people born before 1970, who were more likely to have been exposed to the virus, given the wide spread of measles, and federal guidance says these people have no natural immunity. It is assumed that you have .

However, the same guidance suggests that people at high risk of infection, such as healthcare workers, military personnel, and international travelers, should receive the MMR vaccine regardless of their year of birth.

Still confused?

What to do if you don't have a vaccination record or can't remember if you had measles as a child? Experts suggest simply taking MMR to be safe.

“If you're concerned about whether you've been vaccinated, it's actually cheaper and easier to get revaccinated,” said Dawn Bowdish, an associate professor and immunologist at McMaster University.

What do I need to know if I'm traveling outside of Canada?

World Health Organization officials warned this week that “massive and devastating” measles outbreaks have been reported in more than 50 countries.

So if you or a family member hasn't been vaccinated against measles before traveling, it's even more important to have up-to-date vaccinations, as you're at higher risk of contracting measles, health experts warn. There is.

That's because measles can linger in the air for up to two hours (yes, time) after the infected person enters the space.

The Public Health Agency of Canada (PHAC) says infants under the age of one are “particularly vulnerable” to measles infection because routine immunizations usually begin at 12 months of age.

In a statement, PHAC told CBC News its current advice for international travelers is as follows:

• Infants 6 months to <12 months: 1 dose if traveling to high-risk areas. (However, children who receive the vaccine early will need two more doses, so that vaccination is considered a "zero dose" for their records.)
• Children and adolescents: 2 doses.
• Adults born after 1970: 2 doses.
• Adults born before 1970: At least 1 dose.

See | How to protect yourself from measles:

How to protect yourself from measles

With possible community transmission of measles in some cities and an alarming increase in cases overseas, health officials are warning Canadians to make sure their vaccinations are up to date. ing. The National asks experts to find out more about how we got here and what we can do to protect ourselves from one of the world's most infectious viruses.

If I need a vaccination, how can I get it?

If you need an MMR injection, your health care professional should talk to your primary care provider, such as your doctor or nurse if you have one, or contact your local community health center or public health team. We are proposing.

Travel clinics are an option for getting vaccinated immediately before your trip, but private companies can charge upwards of $75 per dose.

Still, it's not always easy.

Despite being advised to stay up to date on measles vaccinations, multiple Canadians told CBC News that some doctors and pharmacies are Is there a shortage of supply?Or they may simply discourage patients from returning for a follow-up visit because they are too young or too old.

“I think we're all adjusting to the reality that measles is coming back from overseas,” said Shelley Bolotin, director of the Center for Vaccine Preventable Diseases at the University of Toronto. “And maybe that's why different people exist in different places.”

Is there enough supply of the MMR vaccine in Canada?

If you absolutely need to be vaccinated, there are currently two types of MMR vaccines in use in Canada, from pharmaceutical companies Merck and GSK.

Shortage notices have also been posted for both brands of vaccines, but Health Canada says both companies have assured them they are able to “fully meet demand” for public immunization programs, including routine childhood vaccines. Stated.

GSK told CBC News that the “temporary” shortage of the Prioryx vaccine is related to increased demand in Canada's private market, adding that it continues to meet public sector demand. Merck Canada said it is working with provincial and federal health authorities to provide stable supply in a “timely” manner.

What's unclear for Canada's health teams is whether the surge in demand will continue to further complicate vaccination efforts.

“We have to be smart. Our resources are limited,” said Ottawa's Abdullah. “And we have to be thoughtful about how we use it. [the available supply]. ”

Dr. Alan Grill, a family physician in Markham, Ont., said his team is currently distributing measles vaccines as needed.

“If we suddenly decided to focus all our attention solely on everyone's measles vaccination status, you can imagine how disrupted family health care would be.”

Meanwhile, Andrew Cisnet, president of travel vaccine provider Summit Health, said his company rarely administered MMR vaccinations until this year. However, demand has recently skyrocketed, making it difficult to order more.

“From a private sector perspective, there are concerns that we won't be able to procure enough.”

Watch | Measles is endemic in some communities in Canada.

Health officials warn that measles may be spreading in some areas

Measles cases in Greater Montreal and north of Toronto are worrying health officials. Two of the cases are not linked to international travel or to any other known cases in Canada. They say this could mean the virus is spreading in the community and are urging people to get vaccinated.

How protective are previous infections and vaccinations against measles?

If you've had measles before, there's a silver lining.

peer-reviewed research The team, including Bolotin, emphasized that immunity to measles is thought to be lifelong.

The study cites evidence from the remote Faroe Islands off the coast of Denmark, where there was a measles epidemic in 1781. In the next epidemic in 1846, all people over 65 were spared. That means everyone who would have been infected at exactly 65 years of age survived. Before.

“This early observation is some of the best evidence for lifelong immunity to measles,” the research team wrote.

That's because of how the measles virus works, Bowdish said.

“Unlike RSV, influenza, and other respiratory infections, it actually infects our immune cells,” she says. “Then it hijacks those immune cells and travels to the lymph nodes, where it infects millions more immune cells.”

Such a serious infection requires a serious immune response, Bowdish said. It's like your body fighting a major war, giving your body a deep and lasting memory of how to fight off an attacker should they invade you again.

So does the same apply when getting a full set of MMR shots?

Yes, to some extent.

Bolotin said the measles vaccine contains a small amount of live virus and is one of the most protective immunizations available, with studies showing it to be 97% effective after two doses. (how effective it is in ideal, controlled environments) and said it has been shown to be 94% effective. Validity in field estimation (real-world performance).

“It's actually a small infection inside the body, so it causes symptoms that are very similar to what you would see if you had an infection.”

Both Boudish and Bolotin agreed, saying that immunity after vaccination can wane over time. Various global research Occasional breakthrough infections have been recorded. Still, there is evidence that vaccination can still prevent serious illness and help reduce transmission.

“With most vaccines, what we do is modify or minimize the severity of infection rather than prevent infection 100 percent,” Bowdish said.

“But the measles vaccine is a different story; it appears to actually prevent the majority of people from developing the infection.”