Copyright The New York Times
Canada has officially lost its status as having eliminated measles, the highly infectious virus that was considered wiped out in the country as of 1998, the federal health agency announced on Monday. While there have been some limited outbreaks in recent decades, the disease made a resurgence in October 2024. It took hold in several provinces and spread for more than 12 consecutive months, the threshold set by the World Health Organization for a country to lose its elimination status. Canada has logged more than 5,000 measles cases in the last year, with most of them reported in two provinces: Ontario, the most populous, with about 2,400 cases, and Alberta, with nearly 2,000 cases. How did Canada get here? A combination of falling vaccination rates and a collision between politics and public health policy in the post-pandemic era have contributed to Canada’s outbreak. Across Canada, 79 percent of 7-year-olds were fully vaccinated against measles as of 2021, the most recent year for which data are available, down from 83 percent in 2019. That’s far lower than the 95 percent threshold that experts say is needed to stop the virus from spreading. The highest concentration of cases in Canada has occurred in Alberta, a western province that has emphasized personal freedoms to reject vaccination. Politicians and health officials clashed in April, when the province’s top doctor resigned just as the virus was gaining new footholds in Canada. An investigation by The New York Times found that at key points, health officials were stymied from ramping up measles messaging. Culturally conservative Mennonite communities have been a focus of the outbreak, according to Dr. Marina Salvadori, a pediatric infectious disease researcher and medical adviser to the Public Health Agency of Canada. Such groups historically have been less likely to accept vaccines, though the government has not provided precise demographic data on cases. The virus has erupted in some other places with significant Mennonite communities, including West Texas and Chihuahua, Mexico. Public health experts in Canada are concerned that measles is a harbinger for the return of other diseases, like polio, that were formerly concerned tamed. “Measles is the canary in the coal mine because of its phenomenal transmissibility,” said Dr. Brian Ward, a professor who studies infectious diseases at McGill University in Montreal. Once one country loses its disease elimination status, the entire Americas region is also seen as having lost its status. The designation is made by an independent group of experts at the Pan American Health Organization, a regional office of the W.H.O. representing 35 countries in the Americas. What is Canada doing now? A spokesman for the Canada’s health minister, Marjorie Michel, said she is “following the situation closely” and working with provincial health officials. In response to the Times investigation of Alberta’s messaging on measles vaccines, Maddison McKee, a spokeswoman for the province’s health minister, noted that new cases had fallen to single digits in recent months. “Public health officials implemented targeted vaccination campaigns, expanded clinic hours and launched provincewide outreach,” Ms. McKee wrote in an email. “Since March, more than 130,000 measles vaccines have been administered across Alberta — a 50 percent increase compared to the same period last year.” To regain its elimination status, Canada will have to show that it has had no endemic virus spread over 12 consecutive months. To do that, public health experts say, Canada will have to increase the reach of vaccination. “It’s really the best tool in our arsenal to end an outbreak,” said Dr. Shelly Bolotin, the director of the Centre for Vaccine Preventable Diseases at the University of Toronto Dalla Lana School of Public Health. The United States, which has reported over 1,600 cases, would reach that milestone in January and for Mexico, with over 4,000 cases, it would be in February. Other countries with active outbreaks are Belize, Bolivia, Brazil and Paraguay. It can take several years for countries to regain their elimination status, said Dr. Alvaro Whittembury, an immunization expert at the Pan American Health Organization. He pointed to the example of Brazil, which lost its status in 2019, stopped the endemic spread in 2022, and regained its status in 2024. Rebecca R. Ruiz contributed reporting from London.
