Abstract
OBJECTIVE: To document and compare risk factors and control measures for the largest measles outbreaks in the post-elimination era in the Region of the Americas. METHODS: Description of risk factors such as vaccination coverage, notification rate of suspected cases, measles incidence, and a summary of control measures for major measles outbreaks in six countries from 2017 to 2023. The analysis also includes a review of outbreak characteristics (time, place, and person). RESULTS: Between 2017 and 2023, 19 countries in the Americas reported a total of 50 082 cases and 121 deaths from measles. Of these cases, 49 738 (99.3%) were reported in six countries: Argentina, Brazil, Colombia, Mexico, the United States of America, and Venezuela. In two of these six countries, endemic transmission was reestablished due to the presence of risk factors that could not be managed with the control measures initially established. Between 2017 and 2019, the predominant genotypes and lineages were the MVi/Hulu Langat.MYS/26.11 (D8) lineage and the Gir Somnath.IND/42.16 (D8) lineage. CONCLUSIONS: Countries that had better coverage with two doses of measles, rubella, and mumps vaccine, optimal notification rates, and incidence rates of less than 5 cases per million population responded better and faster to measles outbreaks and were able to interrupt virus transmission before 12 months of circulation.