Measles has returned as a serious public-health concern in Canada, leading to the revocation of its measles-free elimination status after more than twelve months of uninterrupted transmission. The Pan American Health Organization (PAHO) officially confirmed that Canada has lost its measles elimination status, and by extension, the entire Americas region has been stripped of that designation.
Measles first reappeared on a large scale in Canada beginning in late October 2024, and by 2025, over 5,000 confirmed cases had been reported—far surpassing prior years’ totals and raising alarms among public-health experts. The outbreak has been especially severe in several provinces and in communities where vaccination rates have dipped significantly below the threshold needed for herd immunity.
Measles is among the most contagious viruses known: a single infected person can transmit it to many susceptible contacts, particularly in settings with low vaccine uptake. The standard of elimination means that a country has interrupted continuous, endemic spread of the virus for at least 12 months. In Canada’s case, this criterion has not been met. Measles elimination in Canada was first achieved in 1998. At that time, regular chains of local transmission had essentially ceased, thanks to strong immunisation efforts and surveillance systems. But this outbreak marks a significant reversal of decades of progress.
Measles outbreaks have now been documented in most of Canada’s provinces and one territory, including Alberta, British Columbia, Manitoba, New Brunswick, Nova Scotia, Ontario, Prince Edward Island, Quebec, Saskatchewan, and the Northwest Territories. Many of the cases are concentrated in under-vaccinated communities, where vaccine access may be limited or mistrust of immunisation has grown.
Measles cases in Canada have significantly outpaced those in the U.S. this year, despite Canada’s smaller population. The U.S. is now also at risk of losing its own measles-free status if sustained local transmission continues into January. Measles remains preventable through vaccination — specifically with the combined measles-mumps-rubella (MMR) vaccine. Two doses are approximately 97% effective at preventing infection. Public-health authorities say that vaccinating 95% or more of the population is critical to stopping sustained spread.
Measles in 2025 has accounted for more than 12,500 confirmed cases across ten countries in the Americas, with roughly 95 % of those cases concentrated in Canada, Mexico, and the U.S. in this current resurgence. Of those, two deaths have been reported in Canada so far.
Measles transmission in Canada has been driven in part by vaccination gaps in specific regions. For example, in one area of Alberta (South Zone, including Calgary) just 68 % of children under two were immunised by 2024 — far below the 95% target. Experts have identified multiple contributing factors: limited access to general practitioners, absence of a national vaccination registry, growing misinformation about vaccine safety, and a lack of effective outreach to hesitant communities.
Measles outbreaks have been found to spread more readily in close-knit communities with low vaccine uptake. Some of the hardest-hit areas include religious or cultural groups where vaccination is lower, and jurisdictions where exemptions to vaccine mandates are more easily available. The interconnectedness of outbreaks across Canada, the U.S., and Mexico underscores how mobility and travel can facilitate spread when vaccine coverage is insufficient.
Measles infections carry serious risks: in addition to the characteristic rash and fever, complications may include pneumonia, brain swelling (encephalitis), blindness, and in some cases, death — especially in infants and unvaccinated individuals. The resurgence of measles is also a wake-up call that other vaccine-preventable diseases could re-emerge if immunisation systems continue to erode.
Measles elimination status is not permanent. A region or country can regain the status if it interrupts endemic transmission for at least 12 consecutive months and maintains high vaccination coverage, strong surveillance, and swift outbreak response — according to PAHO’s regional framework. Canada has been advised to present an action plan under that framework, focusing on boosting immunisation, strengthening data sharing, enhancing surveillance systems, and ensuring rapid outbreak response.
Measles outbreaks also place a strain on health systems: containment requires substantial coordination, resources for diagnosis and contact tracing, and outreach to hard-to-reach populations. Public-health officials say that improving vaccination rates is the most efficient means to prevent outbreaks rather than managing them after they occur.
Measles vaccine hesitancy has been amplified in recent years by social-media spread of misinformation, growing distrust in institutions after the COVID-19 pandemic, and logistical barriers to access (such as clinic hours, geographic access, and record-keeping). Canadian immunologist Dawn Bowdish of McMaster University described how systemic weaknesses in access and outreach have “broken down” to contribute to the current situation.
Measles control at the community level requires not only the vaccine supply, but trust in public-health messaging, accessible services, and targeted efforts to reach communities with historically lower immunisation. Many experts say that simply offering vaccines is not enough — mobile clinics, community champions, culturally-tailored messaging, and strong data systems are also vital.
Measles in the Americas had been declared eliminated in 2016, making the region the first in the world to achieve that milestone. That status was later lost temporarily in the past — for instance, in Venezuela in 2018 and Brazil in 2019 — but was regained in 2024. The loss in Canada means the region is now once again considered to have endemic measles transmission.
Measles elimination status is symbolic, but it matters: when a country is verified as measles-free, it indicates that chains of local transmission are interrupted and rapid containment of imported cases is possible. Losing that status signals vulnerabilities in the immunisation system and potentially exposes the country to larger outbreaks.
Measles outbreaks generally begin in pockets of unvaccinated individuals, then spread when immunity thresholds are not met. Health agencies say that achieving around 95 % coverage with two doses is essential to prevent sustained outbreaks. In many provinces of Canada, immunisation rates have not reached that level in recent years, providing fertile ground for the virus to propagate.
Measles data from Canada show that a strong majority of cases are either unvaccinated or with unknown vaccination status. For example, one PAHO report noted that 89 % of cases in the region occurred in people without documented vaccination. These numbers point clearly to vaccine coverage gaps as a root cause, rather than vaccine failure.
Measles control also depends on high-quality surveillance: being able to quickly detect and investigate cases, identify contacts, and respond with isolation or immunisation interventions. Gaps in data sharing between provinces or in immunisation registries hamper a swift response. Canada’s lack of a national vaccination registry has been flagged as a concern.
Measles resurgence in Canada has shown how outbreaks can escalate when immunity dips and vulnerable groups are left behind. While the overall national immunisation average may appear decent, regional heterogeneity matters: some communities may have very low coverage, which can serve as outbreak ignition points. Measles spread has also been aided by travel-related importations. Because the virus remains in circulation internationally, when individuals travel into Canada (or out of Canada) and then interact with under-vaccinated populations, the risk of sustained transmission increases. The PAHO noted that active outbreaks in Canada, the U.S., Mexico, Bolivia, Brazil, Paraguay, and Belize have been triggered largely by imported cases.
Measles public-health messaging emphasises that the best protection is vaccination. The MMR vaccine protects not only against measles, but also against mumps and rubella, representing efficient use of resources. According to health authorities, it must be given in two doses for full protection.
Measles outbreaks also highlight that vaccine mandates, while helpful, are not sufficient on their own; ensuring coverage, enforcing exemptions appropriately, and maintaining public trust are equally vital. In some Canadian provinces, exemptions are easy to obtain or enforcement is weak, which allows coverage gaps to persist.
Measles in Canada is a cautionary tale for other countries with previously strong immunisation records: gains can be reversed if vigilance wanes. The fact that the U.S. is now on the brink of losing its elimination status illustrates how even nations with advanced healthcare systems can be vulnerable.
Measles elimination efforts going forward will require sustained political commitment, funding for public-health infrastructure, robust immunisation programmes, and community-focused strategies to reach the under-vaccinated. The PAHO emphasised that the region can recover its elimination status — “we have eliminated measles twice, we can do it a third time,” as its Director Jarbas Barbosa stated. Measles in Canada now will test how quickly and effectively the country can mobilise its public-health systems, restore vaccine coverage, and close the gaps that allowed this outbreak to take hold. While the loss of status is a serious setback, health experts emphasise that the situation is reversible — if decisive action is taken.