The Pan American Health Organization (PAHO) has issued a call to action for countries across the Americas, including the Caribbean, to enhance surveillance, laboratory diagnostics, outbreak response, and vaccination campaigns. This urgent appeal follows the loss of the region’s measles-free status, a significant setback in public health. The decision was made by the PAHO Measles, Rubella, and Congenital Rubella Syndrome Elimination Regional Monitoring and Re-Verification Commission during a recent meeting in Mexico City. The Commission confirmed that endemic measles transmission has been reestablished in Canada, where the virus has circulated for at least 12 months. This marks the first time the Americas, which previously achieved measles elimination twice, have lost this status. As of November 7, 2024, 12,596 confirmed measles cases have been reported across 10 countries, with 95% of cases concentrated in Canada, Mexico, and the United States—a 30-fold increase compared to earlier this year. Tragically, 28 deaths have been recorded, primarily in Mexico. Active outbreaks are ongoing in Canada, Mexico, the United States, Bolivia, Brazil, Paraguay, and Belize, largely driven by imported cases. PAHO emphasized that transmission primarily affects under-vaccinated communities, with 89% of cases occurring in unvaccinated individuals or those with unknown vaccination status. Children under one year old are the most vulnerable group. Measles, a highly contagious disease, can lead to severe complications such as pneumonia, encephalitis, blindness, and death. Vaccination remains the most effective preventive measure, having saved millions of lives over the past decades. However, regional vaccination coverage for the second dose of the measles, mumps, and rubella vaccine (MMR2) has plummeted to just 7%, far below the 95% threshold needed to prevent outbreaks. PAHO is providing technical support to affected countries, deploying experts, and monitoring risks in Belize, Brazil, and Paraguay. PAHO Director Dr. Jarbas Barbosa urged countries to redouble efforts, emphasizing that cooperation, solidarity, and science can overcome this challenge. The Americas have previously regained measles elimination status after setbacks, and PAHO remains confident that the region can achieve this once more through sustained vaccination, surveillance, and outbreak response.