Canada might lose its “measles-free” designation due to an ongoing outbreak that started in New Brunswick exactly one year ago.
Recognized by the World Health Organization, Canada achieved “eliminated” status in 1998. This status requires 12 consecutive months without confirmed cases of community transmission, although imported cases from travelers are still counted.
For nearly three decades, Canada’s annual incidence of measles has been extremely low, at about 0.87 per million. However, this marked a significant change in October 2024 after a case traced back to a large Mennonite gathering.
The outbreak spread through Mennonite communities in Ontario, where vaccination rates are often low due to specific cultural and religious beliefs. Additionally, the disruptions caused by the Wuhan coronavirus pandemic have affected regular vaccination for measles, mumps, and rubella.
One year after the outbreak began, public health officials reported a total of 2,375 cases in Ontario and 1,925 in Alberta. New Brunswick declared its outbreak over in January, but Public Health Ontario believes no new cases have emerged past the incubation period for measles, indicating the outbreak could soon be officially declared over.
Currently, Canada’s measles infection rate is about thrice that of the United States. The US reported 1,618 infections over the past year, with a population 8.5 times larger than Canada. Meanwhile, Mexico is also facing a significant measles outbreak, with case numbers similar to those in Canada.
Officials in Ontario pointed out that around 75 percent of the cases were among children, with 96 percent of those being unvaccinated. Tragically, two infants who were infected died after their mothers gave birth prematurely—one in Ontario and the other in Alberta.
The Pan American Health Organization, which is the WHO’s branch for the Americas, is set to meet in November to discuss Canada’s measles elimination status. To revoke this status, there needs to be 12 consecutive months of community transmission, which seems to be happening in Ontario and Alberta.
The US and Mexico will have their status reviews in January and February, respectively. The US almost lost its status in 2019 due to a New York outbreak but managed to avoid decertification. Meanwhile, New York and South Carolina are dealing with smaller outbreaks at this time.
