Measles outbreaks in Ontario and other parts of Canada raise alarm

Canada’s top doctor is encouraging un- and under-vaccinated Canadians to seek protection against measles as cases of the incredibly contagious illness rise in Ontario and Quebec.

This week, Theresa Tam, the country’s chief public health officer and the second-in-command at the Public Health Agency of Canada, said that Canada is experiencing an uptick in measles activity associated with outbreaks in Canada’s two largest provinces. Adding that the outbreaks were initially associated with travel, PHAC’s statement says people have also been infected after exposure to the virus in Canada. 

As recently as last week, Toronto Public Health warned that residents might have been exposed to the virus on Turkish Airlines Flight TK17 (Istanbul to Toronto), which arrived at Toronto Pearson International Airport on Jan. 22.

According to a Jan. 16 report by Public Health Ontario, 65 cases (39 confirmed and 26 probable) of measles have been reported in the province in 2024 and 2025, with two new cases recorded since the last report was issued on Dec. 19, 2024. 

The report says all cases were reported in people born in or after 1970, with 44 reported in children and adolescents and 21 in adults. The report says 41 of the impacted children and 11 of the adults were not immunized. The immunization status of several other people who fell ill is not known. A small number of infected individuals were fully or partially vaccinated. 

Cases have been reported by 11 public health units from across Ontario, with 26 cases (the most of any region) reported by the Southwestern Public Health Unit, which serves Oxford County, Elgin County and St. Thomas.

The report says six cases have been reported in Hamilton (with one child under the age of five dying in 2024), one in Durham, three in Halton, three in Peel (Brampton, Mississauga and Caledon), 10 in Toronto and one in York region. Cases have also been reported by Grand Erie Public Health, the Grey Bruce Health Unit, the Middlesex-London Health Unit and the Windsor-Essex County Health Unit. 

The report says nine people were hospitalized with the disease, eight of which were children. One child succumbed to the illness. 

The report says all hospitalized children, as well as the one who died, were not vaccinated against measles. 

As for where the individuals contracted the virus, the report says 18 cases were associated with travel and two of those cases led to further transmission last spring. Three cases occurred in individuals with unknown sources of exposure and since October, an out-of-province exposure to a travel-related case of measles in New Brunswick led to 38 cases (12 confirmed, 26 probable) in the Southwestern, Grey Bruce, and Grand Erie public health units. One child infected in connection with this outbreak was hospitalized. 

In a statement, PHAC said Canadians should ensure they are fully vaccinated against the highly contagious, airborne disease that can, in some cases, lead to serious health complications, including respiratory failure, encephalitis (swelling of the brain), pregnancy complications and death.

PHAC also said that measles can spread quickly, adding that 90 per cent of people who are not vaccinated or haven’t had measles before can become infected if they are near someone with the disease. 

“I’m concerned that vaccination rates for measles among children are not high enough in some areas of Canada to prevent the spread of measles,” Tam said in a statement. 

“For instance, a recent study in the Canadian Journal of Public Health found that there was a decline in measles vaccination coverage in children in 2023 compared to 2019.” 

The vaccine given to prevent measles (the measles, mumps, rubella or MMR vaccine) is not new and two doses–typically given to children at one year of age and again between the ages of four and six–typically provide lasting protection. 

According to Health Canada, the efficacy of a single dose given at 12 or 15 months is 85 to 95 per cent and with a second dose, efficacy is almost 100 per cent. 

Public Health Ontario says symptoms of measles include fever, a red blotchy rash, red, watery eyes, and cough. While most people who contract the illness can recover at home, severe complications are possible.

People most at risk of complications include children under five, those with compromised immune systems and unimmunized pregnant women. 

Adults and older children who have not been vaccinated with one or two doses can speak to their health care provider about starting or completing the series. While the vaccine is very effective, additional or booster doses are not appropriate for everyone, especially those who are immunocompromised or pregnant. 

In a release, PHAC says that the measles vaccine has saved more lives globally than any other vaccine, adding that the World Health Organization estimates that more than 60 million children’s lives have been saved by the shot since 2000.

Last year, Peel Public Health told INsauga.com that anyone experiencing measles symptoms should stay home from school and work to prevent further spread and contact their doctor to discuss possible next steps. Those who suspect they have measles can also contact public health if they do not have a family doctor or their doctor is unavailable.