Key Points

• In 2025, 139 cases of measles were reported in the region (the same as in 2024), confirming the resurgence observed since September 2023. Of these cases, 14% were imported.
• For the third consecutive year, the regional case rate was higher than that of the rest of mainland France (1.68 cases vs. 1.26 cases per 100,000 inhabitants).
• In the spring of 2025, the number of measles cases was particularly high, linked to a major outbreak involving 75 cases across 18 departments in mainland France following attendance at a Parisian trade show.
• The median age observed was 17 years, an increase compared to previous years.
• In the ARA region, the departments of Isère and Haute-Savoie accounted for nearly 60% of cases, with outbreaks occurring between March and May 2025 in schools and community settings.
• In 2025, the highest incidence rates of measles cases were observed among 10- to 14-year-olds and 15- to 19-year-olds.
• Of all cases reported in 2025, more than half were unvaccinated, and 11% had received only one dose.