The Pan American Health Organization (PAHO) has officially stripped Canada of its hard-won measles elimination status, marking the end of a nearly three-decade public health achievement and signaling a dangerous new phase in the resurgence of the highly contagious virus across North America.
The decision, announced on Monday, was triggered by the sustained transmission of the same measles strain in Canada for over 12 consecutive months. The loss is a direct consequence of falling childhood vaccination rates, and health officials are now warning that the United States, facing its own significant rise in cases, is on a precarious path to losing its status as well.
The Tragic Criterion: A Full Year of Spread
The World Health Organization (WHO) and PAHO deem a country to have eliminated measles when there is no continuous spread of linked cases within local communities for at least 12 months.
- The Breakdown: Canada’s current, multi-jurisdictional outbreak began in October 2024 and has since spread to nearly all provinces and one territory. Despite recent efforts to slow its spread, the Public Health Agency of Canada (PHAC) confirmed that the sustained transmission of over a year, primarily within under-vaccinated communities, compelled PAHO to revoke the status.
- The Numbers: Canada has logged over 5,100 confirmed measles cases this year, resulting in two confirmed deaths—both tragically being pre-term babies infected in utero. The case count significantly exceeds the sporadic, travel-related cases that had previously defined Canada’s decades-long elimination success.
- The Culprit: Experts point directly to slipping national vaccination coverage. Data shows Canada’s two-dose MMR (measles, mumps, and rubella) vaccine coverage has dropped significantly, falling well below the 95% threshold needed to maintain herd immunity and prevent the virus from spreading widely. About 89% of reported cases in the region have occurred in individuals who were unvaccinated or whose vaccination status was unknown.
The Americas on Edge
Canada’s loss carries a regional penalty: because the virus is spreading continuously within one of its member states, the entire Region of the Americas has now lost its verification as free from endemic measles transmission, a designation it only regained last year after Venezuela and Brazil contained their own outbreaks.
This regional setback places intense pressure on the United States, which has technically held its elimination status since 2000.
- U.S. Case Load: The U.S. is currently reporting outbreaks and a significant increase in cases, contributing to the nearly 12,600 confirmed cases reported across ten countries in the Americas this year. While the U.S. has not yet met the 12-month sustained transmission criterion, it is grappling with pockets of alarmingly low vaccination rates in several states.
- The Risk: Public health leaders fear that the sheer volume of cases now circulating in neighboring Canada and Mexico exponentially increases the risk of the virus taking hold in under-vaccinated U.S. communities. National two-dose MMR coverage for U.S. kindergartners was already estimated to be below the 95% target, creating vulnerable populations.
Dr. Jarbas Barbosa, Director of PAHO, called the loss of elimination status “a setback,” but stressed that it is “reversible.” He urged all countries in the Americas to immediately redouble efforts to strengthen vaccination rates and surveillance to interrupt transmission and reclaim the collective public health achievement.