Canada is on the brink of losing its measles elimination status after a full year of continuous transmission, a development that also places the United States at risk due to widespread outbreaks. This potential reversal highlights the severe consequences of declining vaccination rates and underscores the fragility of public health achievements in the Americas.
The outbreak in Canada began in October 2024 and has now persisted for 12 months, meeting the World Health Organization’s criterion for losing elimination status, defined as the absence of local virus transmission for any period longer than a year. With over 5,000 measles cases reported this year alone—more than twice the total recorded in the past 25 years combined—the scale of the outbreak is unprecedented. Hundreds of hospitalizations and two deaths in infants have occurred, emphasizing the severe health impacts. The Pan American Health Organization (PAHO), a regional WHO office, will convene in early November to formally determine the status, likely revoking Canada’s elimination achievement from 1998.
Falling vaccination rates are a primary driver of this crisis, with MMR coverage declining in both Canada and the U.S. In Canada, data from six jurisdictions shows the share of 2-year-olds receiving at least one MMR dose dropped from nearly 90% in 2019 to less than 83% in 2023. Similarly, in the U.S., kindergarten MMR coverage has been below the 95% federal target for five consecutive years, a benchmark necessary to prevent the spread of the highly contagious disease. The COVID-19 pandemic exacerbated these trends by disrupting healthcare services and amplifying misinformation, leading to increased vaccine hesitancy. About 90% of measles cases in Canada are among unvaccinated individuals, revealing critical immunity gaps.
The United States faces a parallel threat, with ongoing outbreaks in multiple states pushing it toward the same fate. Active transmission is documented in six countries, including the U.S. and Mexico, with hotspots in South Carolina, Arizona, Utah, and previously in Texas. The Texas outbreak, which ended in August, involved 762 cases over seven months and resulted in three deaths—all unvaccinated individuals. If transmission continues and is linked to ongoing outbreaks into January, the U.S. could lose the elimination status it earned in 2000, a historic achievement now in jeopardy.
PAHO’s upcoming meeting will review the broader regional situation, requiring countries that lose elimination status to submit corrective action plans focused on intensified vaccination, strengthened surveillance, and rapid outbreak response. This process mirrors past experiences in Venezuela and Brazil, which regained status only after years of extensive efforts. The Americas region as a whole had eliminated measles in 2016 but lost it temporarily, regaining status last year, yet it remains under threat due to current outbreaks.
Experts warn that losing elimination status could have profound consequences, including preventable deaths and the re-establishment of measles as an endemic disease. Dr. Dawn Bowdish, an immunologist at McMaster University, noted that this situation exposes vulnerabilities in public health systems, comparable to countries disrupted by war or civil unrest. She emphasized the need for constant vigilance and consistent support for vaccination programs to effectively combat infectious diseases, highlighting how misinformation and liberal exemption rules in some provinces have created vulnerabilities.
Public health responses are underway but face significant challenges. In South Carolina, a mobile vaccination unit deployed to an outbreak area saw limited uptake, with only 21 people vaccinated over a week, mostly adults who contribute less to herd immunity in schools. Similarly, in Utah, MMR vaccinations increased by 32% statewide but only 16% in the Southwest district where an outbreak is growing, widening coverage disparities. Researchers attribute vaccine hesitancy to a complex blend of personal, social, and environmental factors, worsened by the infodemic during the pandemic.
Looking ahead, the potential loss of elimination status serves as a stark reminder of the importance of maintaining high vaccination coverage to protect vulnerable populations. Without urgent action to address misinformation, improve access to vaccines, and strengthen public health infrastructure, measles could resurge as a major threat, undoing decades of progress and endangering communities across North America.