Public health risk assessment of measles in the context of religious mass gatherings in South America: Implications for the Americas Region - 8 October 2026

This Rapid Risk Assessment (RRA) aims to assess the public health risk in the Americas Region associated with the mass movement of people due to religious events that will take place in some South American countries (Argentina, Peru, and Uruguay) in the context of the current measles outbreaks and cases reported in 2026 in several countries within and outside the Region, as well as existing immunity gaps in the population.

The classification of the risk as “Very High” is based on the fact that the main factors underlying the assessment conducted on 5 August 2026 still persist, compounded by the high levels of domestic and international travel and the high concentration of people expected to attend these mass gathering events.