The Pan American Health Organization (PAHO) will review whether the United States and Mexico still qualify as free of endemic measles at a meeting from 10 to 13 November, after a year of outbreaks put both countries' elimination status in doubt. The United States has held measles elimination status since 2000.

The review will be carried out by PAHO's Measles and Rubella Elimination Regional Monitoring and Re-Verification Commission, an independent body that assesses every country in the Americas each year. At this closed technical meeting it will examine data for 2025 and the first half of 2026, with particular focus on countries with active outbreaks, including the United States and Mexico. The US review was moved from a special session in April to the commission's regular November meeting, after PAHO said American authorities were still completing analysis, including full viral genome sequencing.

The decision rests on genetics rather than case numbers alone. PAHO defines re-established endemic transmission as the uninterrupted circulation of the same virus genotype and lineage for 12 months or more in a specific area. For the United States, the analysis period starts on 20 January 2025, when the West Texas outbreak began; for Mexico it starts on 1 February 2025. The US Centers for Disease Control and Prevention had counted 4,852 confirmed measles cases this year as of 29 October.

The commission does not announce a ruling itself. It sends recommendations to PAHO's director, who formally communicates the classification to national authorities. The stakes are high: the Americas region as a whole lost its measles-free status in November 2025, after endemic transmission was judged to have been re-established in Canada. Full details are in the Medical Daily report.