Public health nurse Lauri Bidinot demonstrates how to give a measles shot to a young girl at Southwestern Public Health in St. Thomas, Ont. on March 4, 2025.Geoff Robins/The Canadian Press
On Friday, May 2, Globe health reporters Kristy Kirkup and Alanna Smith, and health editor Caroline Alphonso, answered reader questions on the measles outbreak in Canada.
Since last October, Canada has experienced a multijurisdictional measles outbreak. Cases have slowed down in places such as Quebec, but others haven’t been so lucky. As of April 24, Ontario’s ballooning measles outbreak surpassed 1,000 cases. The province has 10 times more cases than it experienced during the entire decade of 2013-23. Meanwhile, Alberta confirmed 137 cases.
Readers asked about the symptoms to look for, which communities are most affected, how vaccinations work in these cases, and the travel advisories that are in effect. Here are some highlights from the Q+A.
This Q&A has been edited for clarity.
Measles symptoms and health effects
What are the symptoms of measles besides rashes in babies and adults? How long is it contagious?
Alphonso: Measles is known for its distinctive rash that typically appears about 3 to 5 days after the first symptoms. It usually starts with a high fever, cough, runny nose, red and watery eyes. Severe complications can include pneumonia, brain swelling and even death.
What is the death rate for measles? What is the rate of serious injury/long-term effects?
Kirkup: It is estimated deaths from measles occur 1 to 10 of every 10,000 cases of measles in higher income countries like Canada. Severe complications, which can include respiratory failure and encephalitis, is estimated to occur in approximately 1 of every 1,000 reported cases. These statistics are posted on Health Canada’s website, which you can find here.
What does getting measles do to your immune system? Does infection leave you immune or add to ‘herd immunity’?
Smith: One of the most dangerous features of measles is that it can induce what’s called immune amnesia. This essentially wipes out your body’s immune memory, making you more susceptible to other diseases – including ones you have already fought off in the past.
Measles can spread rapidly: You can even get measles by being in the same room where a person with measles has been, even if the infected individual has left. Due to the highly contagious nature of measles, herd immunity requires about 95 per cent of the population to be vaccinated.
It is highly unlikely to get measles more than once, considering most people develop lifelong immunity after infection. The Public Health Agency of Canada has said that to be immune, you must either be fully vaccinated or have had a lab-confirmed measles infection.
The state of measles in Canada
When was the last time Canada experienced a major measles outbreak?
Alphonso: Canada is in its worst year for measles since 2011, when 751 cases were diagnosed, most linked to an outbreak in Quebec.
What measles travel advisories are in place? Could this affect Canadians’ ability to travel abroad if the outbreak worsens?
Smith: There are not currently any mandatory travel restrictions for measles, such as quarantine, but it is highly recommended that people who are traveling to countries experiencing high rates of transmission are fully vaccinated.
The Public Health Agency of Canada is advising people planning travel to consult a health care provider at least six weeks before travel, especially if you are unsure whether you have received the measles, mumps and rubella, or MMR, vaccine. One dose is about 93 per cent effective at preventing measles; two doses, roughly 97 per cent.
Because measles is highly contagious and spreads easily across borders, there are many countries currently experiencing outbreaks. Here is a list from the U.S. Centers for Disease Control and Prevention.
PHAC stresses that if you do have symptoms of measles, you should not travel. If symptoms begin to show during travel back to Canada, it is recommended to wear a mask and limit contact with other people.
Long story short: there’s currently no need to worry about vacation plans.
It is my understanding that this outbreak is mainly centred in the Mennonite community. They appear to be resistant to any vaccinations. Why is that and why don’t the media explore this issue?
Kirkup: Ontario’s chief medical officer of health, Dr. Kieran Moore, said in a public health memo in March that measles cases on the rise in southwestern Ontario linked back to an exposure at a large gathering with guests from Mennonite communities in New Brunswick last fall. You can see the memo online here. My colleague Kelly Grant also explored this issue in a comprehensive story.
Which communities and demographics are being affected by measles? What are the rates of hospitalization? What is the financial cost of those hospital stays compared to the cost of an immunization?
Smith: Children who are not vaccinated against measles are most affected by the country’s multijurisdictional outbreak. In Ontario, for example, 76.5 per cent of cases are among children, the vast majority of who have not been immunized.
Since October, 84 people have been hospitalized in Ontario for measles, which is about 7 per cent of the total cases. Eight people have been admitted to intensive care units. Among all hospitalizations, 80 were unimmunized, including 63 children.
When it comes to the cost of measles, there is a study published in the National Library of Medicine that showed a 2015 outbreak of 16 measles cases in Ontario cost approximately $1.2-million. You can see the study here.
Measles vaccines and how long protection lasts
How do I know if I have been vaccinated? I remember getting a vaccination at school, but not entirely sure what is was for. I was born in 1961.
Smith: Adults born before 1970 are generally presumed to have acquired natural immunity to measles, considering it was widespread before routine immunizations came into play. The best approach is to consult your medical records but, if that’s not possible, the best course of action is to speak with a healthcare provider.
For those of us who had our vaccination more than 50 years ago, should we be getting a booster?
Smith: Boosters are not recommended at this time in Canada.
Why isn’t vaccination mandatory or enforced? What are the reasons parents are refusing or not accessing them?
Smith: Government at all levels in Canada have long had the same approach: Rather than forcing people to take medications, focus on education and recommendations. This strategy has, generally speaking, been effective.
But childhood vaccination rates have dipped in recent years, prompting conversations about the potential benefit of mandating vaccines and whether to revoke the ability for parents to refuse vaccination for their children based on religious or philosophical reasons.
The Globe’s Health columnist André Picard wrote on this recently:
Opinion: Personal beliefs do not supersede the public good – and vaccination is a public good
Experts who have spoken to The Globe say the decline in measles vaccination coverage is a symptom of fragmented primary care access, lacking immunization programs and medical misinformation. Vaccine hesitancy is a big problem – one that has been fueled in part by mis and dis-information on the safety and effectiveness of the measles vaccine, including by people like U.S. Secretary of Health Robert F. Kennedy Jr.
Why are we permitting freedom to run amok, and do nothing about it? The freedom not to get vaccination is the freedom to hurt countless others. I am 91 years old and got vaccinated as a very young child in Germany where it was mandatory. When I came to Canada in 1955, I needed to show proof of vaccination. Why not start using some common sense?
Kirkup: The notion of what constitutes “freedom” has come up among health care providers. Vaccination against measles through the measles, mumps, rubella or MMR vaccine has been taking place for decades. The World Health Organization say the shot has saved 154 million lives in the last 50 years.
Physicians say science supports the MMR vaccine as safe and effective. However, those who do not support vaccination often point to arguments about personal freedom. In response, public health scholars say immunizations are not only about protecting oneself but rather about protecting other individuals, including those who cannot get the vaccine.
Michelle Barton-Forbes, the chair of the Canadian Paediatric Society’s infectious diseases and immunization committee, told The Globe this year that she is concerned measles is circulating, in part, because people have decided not to immunize their children. She said they do not recognize the social responsibility they have to children who do not have means to protect themselves because they are immunocompromised.
Measles vaccine schedules for children
My 3-year old child has received the one MMR dose they are eligible for. Is this enough protection, given the ongoing outbreaks?
Alphonso: Typically, a child in Ontario receives their first dose at one year of age and the second dose at four to six years (around the time a child starts school). Public health is recommending an accelerated dose if you live in one of the outbreak areas or are travelling there.
I have an eight-week-old at home and was wondering if there are any plans to revise the current measles vaccination schedule. Given the recent outbreaks, I’m curious whether earlier immunization is being considered.
Alphonso: Public-health officials in places like Grand Erie and Southwestern, where we’re seeing a large number of measles cases, have begun offering early MMR shots to babies between six months and one year old. It’s best to speak to your child’s doctor to see if an early dose is recommended.
How can we know if the air in our kids’ schools and daycares is safe? What can we do to make it safer?
Kirkup: This is an issue that has come up recently. An organization called Ontario School Safety wrote a letter asking the Ontario government and provincial public health about the need for healthy indoor air to help curtail the spread of measles.
Depending on where you live, you can find information online about air quality in schools.