Pan American Health Organization (PAHO) has sounded the alarm after confirming that the Americas have officially lost their status as a region free from endemic transmission of measles, over a decade after achieving its elimination. 

The decision was made at the PAHO Regional Commission for Monitoring and Reverification meeting, held in Mexico City from November 4 to 7, 2025. The Commission determined that endemic transmission has been reestablished in Canada, where the virus has circulated for more than 12 consecutive months. 

“This loss represents a setback, but it is reversible,” said Dr. Jarbas Barbosa, PAHO Director. “As long as measles is not eliminated globally, our region will face the risk of reintroduction among unvaccinated or under-vaccinated populations. With political commitment, regional cooperation, and sustained vaccination, we can once again interrupt transmission,” he added. 

As of November 7, 2025, 12,596 confirmed measles cases have been reported in ten countries, with Canada, Mexico, and the United States accounting for 95% of them. Twenty-eight deaths have been reported: 23 in Mexico, three in the U.S., and two in Canada. 

The outbreak in Canada began in October 2024 in New Brunswick and spread nationwide, with over 5,000 confirmed cases. Transmission continues in Alberta, British Columbia, Manitoba, and Saskatchewan. 

Measles is one of the most contagious diseases: a single infected person can transmit it to up to 18 others. It can cause serious complications such as pneumonia, encephalitis, blindness, and even death. Outbreaks also strain public health systems. 

Vaccination remains the most effective protection. Over the past 25 years, measles vaccination has prevented more than six million deaths in the Americas. However, in 2024, the regional coverage for the second dose (MMR2) averaged only 79%, well below the 95% needed to prevent outbreaks. 

PAHO continues to provide technical cooperation to strengthen surveillance, laboratory diagnostics, and vaccination campaigns. Experts have been deployed to Mexico, Argentina, and Bolivia, while monitoring continues in Belize, Brazil, and Paraguay. 

RVC Recommendations 

• Strengthen surveillance, immunization, and rapid outbreak response for every suspected case. 
• Expand national electronic immunization records following PAHO guidelines. 
• Maintain sustainable laboratory surveillance with adequate financial and human resources. 
• Perform PCR testing for suspected cases with negative IgM and clinical or epidemiological risk. 
• Implement recommendations locally and document outbreak closure per the Regional Framework. 

Americas previously lost their measles-free status in Venezuela (2018) and Brazil (2019), regaining it in 2024 thanks to coordinated regional action. To regain elimination status, a country must prove 12 consecutive months without endemic transmission supported by complete vaccination and surveillance data. 

Now, Canada will implement a national action plan focused on improving vaccination coverage, strengthening surveillance systems, and ensuring rapid response to outbreaks. 

“Cooperation, solidarity, and science are stronger than any virus. Together, we can protect the health and lives of everyone across the Americas,” concluded Dr. Barbosa.