PAHO Urges Response After Americas Lose Measles-Free Status

The Pan American Health Organization (PAHO) announces that the Americas no longer hold their status as a region free of endemic measles transmission. The determination followed a review by the Regional Commission for the Monitoring and Reverification of the Elimination of Measles, Rubella, and Congenital Rubella Syndrome, which met in Mexico City on Nov. 4–7. The panel confirmed that sustained transmission of measles has been reestablished in Canada for over a year.

“This loss represents a setback, but it is reversible,” says Jarbas Barbosa, Director, PAHO. “As long as measles continues to circulate globally, the region remains at risk of reintroduction and spread, particularly in areas with low or incomplete vaccination coverage. Yet, as we have shown before, with political commitment, regional cooperation, and consistent immunization, we can once again interrupt transmission and regain this achievement.”

The Americas had previously become the first region worldwide to eliminate measles twice. However, declining vaccination coverage and increased mobility have contributed to renewed outbreaks. As of Nov. 7, 2025, health authorities reported 12,596 confirmed cases in ten countries, a 30-fold rise compared with 2024. Around 95% of these infections occurred in Canada, Mexico, and the United States, along with 28 reported deaths, most of them in Mexico.

Ongoing outbreaks have been identified in Canada, Mexico, the United States, Bolivia, Brazil, Paraguay, and Belize. The majority of cases involve unvaccinated individuals or those with unknown vaccination status. Infants under one year old account for the largest share of infections, followed by children aged one to four.

Measles remains among the most contagious diseases, with a single infection capable of spreading to as many as 18 people. It can result in serious complications, including pneumonia, encephalitis, and death, while straining health services and disrupting daily life.

Vaccination continues to be the primary defense. In the past 25 years, measles immunization has prevented an estimated 6 million deaths in the Americas. Still, in 2024, coverage for the second dose of the measles, rubella, and mumps vaccine averaged only 79%, well below the 95% threshold required to prevent outbreaks. Only about one-third of countries achieved adequate coverage for the first dose, and one-fifth for the second.

PAHO is providing technical assistance to countries to reinforce surveillance, improve laboratory testing, strengthen outbreak control, and expand vaccination campaigns. Specialists have been deployed to Mexico, Argentina, and Bolivia, and the organization continues to monitor risk areas in Belize, Brazil, and Paraguay.

The Commission urges countries to enhance epidemiological surveillance, expand electronic vaccination registries, and ensure sufficient resources for laboratory operations. It also recommends the use of molecular testing to confirm cases and the documentation of outbreak closures under regional standards.

The region has previously faced similar challenges. Temporary losses of measles elimination occurred in Venezuela in 2018 and Brazil in 2019, but both were reversed through coordinated regional efforts. To requalify for elimination status, a country must demonstrate the interruption of endemic transmission for at least 12 months, supported by reliable data on vaccination, surveillance, and response.

“Cooperation, solidarity, and science are stronger than any virus,” says Barbosa. “By acting together, we can once again protect the health of people across the Americas.”