Measles is making a comeback. Should you get vaccinated against measles? And does it protect you for life? | CBC News

This story is part of CBC Health’s Second Opinion, a weekly analysis of health and medical science news emailed to subscribers on Saturday mornings. If you don’t already have a subscription, you can do so by email Click here.

In Canada, measles was once a thing of the past. But it is increasingly becoming a contemporary health threat after declining vaccination rates have allowed the virus to start circulating again.

Canada officially eradicated measles nearly three decades ago, but for years medical experts warned that a comeback was imminent – and disruptions to routine childhood vaccination efforts during the COVID-19 pandemic may have accelerated that.

After tens of thousands of cases in Europe and nearly 100 recent infections in Canada and the United States, health authorities are now on high alert.

There are warnings against traveling abroad, calls to make sure their families are up to date on the measles vaccine and new reminders that the virus is highly contagious and can cause pneumonia, encephalitis and even death.

“A lot of people are worried,” said Dr. Alykhan Abdulla, a family doctor in Ottawa. “Measles hasn’t really existed in our society for a long time.”

So how should Canadians engage with the latest guidance on measles vaccination and who is actually protected? And if you have already received at least one measles vaccination, are you now prepared for life?

Who should get vaccinated against measles?

If you or your child have done this never Have had a combined measles-mumps-rubella (MMR) vaccination and have never had a measles infection before? The official recommendation is simple: get vaccinated.

But after that things get a little more complicated.

For Canadian children, the typical schedule now consists of two doses, both given before starting school. The first dose of MMR should be given when a child is 12 to 15 months old and the second dose at 18 months of age or at any time thereafter, but no later than school entry. Remarks the Canadian vaccination guide.

As for adults, when you were born after After the two-dose MMR vaccine became routine, you probably had both shots as a child.

However, some adults may have only received one dose. That includes people born before 1970 who were likely exposed to the virus because of the earlier spread of measles — and federal guidelines assume those people have natural immunity.

However, the same guidelines suggest that anyone at higher risk of exposure – such as healthcare workers, military personnel and international travelers – should receive an MMR vaccine regardless of their year of birth.

Still confused?

What if you don’t have a vaccination certificate or can’t remember whether you had measles infection as a child? Experts recommend simply taking a dose of MMR for safety reasons.

“If you have concerns about whether you’ve been vaccinated, it’s actually cheaper and easier to just get vaccinated again,” said Dawn Bowdish, an associate professor and immunologist at McMaster University.

What do I need to know when traveling outside of Canada?

More than 50 countries are reporting “large and devastating” measles outbreaks, World Health Organization officials warned this week.

So if you or a family member were not vaccinated against measles before traveling, you are at higher risk of becoming infected, medical experts warn. This makes it even more important to stay up to date on your vaccinations.

That’s because measles can linger in the air for up to two hours (yes, hours) after someone who is infected enters a room.

According to the Public Health Agency of Canada (PHAC), infants under one year old are “particularly vulnerable” to measles infection because their routine vaccinations typically begin at 12 months of age.

In a statement, PHAC told CBC News the current advice for people traveling internationally is as follows:

  • Infants aged between six months and less than 12 months: One dose if traveling to a high-risk area. (However, this vaccination is considered a “zero dose” in your record because children who receive an early dose will need two more doses later.)
  • Children and adolescents: Two doses.
  • Adults born in 1970 or later: Two doses.
  • Adults born before 1970: At least one dose.
VIEW | How to protect yourself from measles:

How to protect yourself from measles

With the potential spread of measles in several cities and an alarming rise in cases abroad, health officials are warning Canadians to make sure their vaccinations are up to date. The National asks the experts to break down how we got here and what you can do to protect yourself from one of the world’s most contagious viruses.

If people need a shot, how can they get one?

If you need an MMR vaccination, medical experts recommend speaking to your primary care provider, such as a family doctor or nurse practitioner – if you have one – or contacting your local community health center or public health team.

Travel clinics are also a way to quickly get a vaccination before a trip, but private companies can charge $75 or more for a dose.

However, it is not always easy.

Despite advice to stay up to date on measles vaccinations, several Canadians told CBC News that some doctors and pharmacies are either experiencing a shortage of supplies or are simply discouraging patients from getting vaccinated again because they are either too young or are too old for it need one.

“I think we’re all getting used to the reality of the resurgence of measles from abroad,” said Shelly Bolotin, director of the Center for Vaccine-Preventable Diseases at the University of Toronto. “And maybe that’s why different people are in different places.”

Is there enough MMR vaccine available in Canada?

If you need a dose, there are currently two MMR vaccines available in Canada from drugmakers Merck and GSK.

There were also reports of vaccine shortages from both brands, but Health Canada said the companies had assured they were able to “fully meet the demand” for public immunization programs, including routine childhood vaccinations.

GSK told CBC News that the “temporary” shortage of its Priorix vaccine is related to increasing demand in the Canadian private market, adding that it continues to meet demand in the public sector. Merck Canada said it is working with provincial and federal health authorities to ensure consistent supply in a “timely” manner.

It’s unclear to Canadian health teams whether a continued surge in demand will further complicate vaccination efforts.

“We have to be careful, our resources are limited,” Abdulla said in Ottawa. “And we have to be careful about how we use it [the available supply].”

The family doctor Dr. Allan Grill of Markham, Ont., said his team is currently distributing measles vaccines as needed.

“You can imagine how overwhelmed general practice would be if we suddenly decided to focus all our attention on everyone’s vaccination status against measles.”

Meanwhile, Andrew Sisnett, president of Summit Health, a travel vaccine provider, said the company rarely distributed MMR shots before this year. But demand has spiked recently and he’s finding it difficult to order more.

“There are concerns that from a private sector perspective we will not be able to procure enough.”

VIEW | Measles is spreading in some Canadian communities:

Health officials warn that measles could be spreading in some communities

Measles cases in the greater Montreal area and north of Toronto are raising concerns for health authorities because two of them are not linked to international travel and are not linked to 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 is a previous infection or vaccination against measles?

If you have already had a measles infection, there is a glimmer of hope.

Peer-reviewed research A team that included Bolotin emphasized that immunity to measles is expected to last lifelong.

The study cited evidence from the remote Faroe Islands, off the coast of Denmark, where a measles outbreak occurred in 1781. The next outbreak in 1846 spared everyone over 65 years of age – i.e. everyone who would have been infected exactly 65 years earlier.

“This early observation remains one of the best pieces of evidence for lifelong immunity to measles,” the team wrote.

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

“Unlike RSV, influenza or other respiratory infections… it actually infects our immune cells,” she said. “And then it hijacks those immune cells to get to our lymph nodes, where there are millions and millions of other immune cells to infect.”

Such a severe infection requires a serious immune response, Bowdish said. It’s a bit like your body is waging a great war, giving it deep, lasting memories of how to fight off this attacker if it ever invades again.

Does the same apply to getting a complete set of MMR shots?

To a certain extent, yes.

The measles vaccine contains small amounts of live virus, making it one of the most protective shots on the market, Bolotin said. Two doses showed 97 percent effectiveness in studies (how well it works in an ideal and controlled environment) and 94 percent effectiveness (real-world performance) in field estimates.

“It’s actually a mini infection in your body. And so it creates something that is very, very similar to what you would see if you were infected.”

There may be cases where immunity after vaccinations wanes over time, both Bowdish and Bolotin agreed various global studies have documented occasional breakthrough infections. Still, there is evidence that the vaccines still protect against serious disease and help curb transmission.

“With most vaccines, we modify or minimize the severity of infections rather than preventing them 100 percent,” Bowdish said.

“But the measles vaccine is another case where it actually seems to prevent the development of infections in most people, most of the time.”

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