Key Points

• Among suspected measles cases occurring between January 1 and December 31, 2024, 483 cases of measles, including 84 imported cases, were reported throughout France. While the number of cases has quadrupled compared to 2023, it remains low compared to the average from the years prior to the COVID-19 pandemic.

• In total, 62 departments reported at least one case. No cases were reported in the overseas territories.

• The age distribution of cases shifted in 2024 toward older age groups, with a median age of 13 years, higher than in previous years.

• The incidence rate of reported cases was 0.58 cases per 100,000 inhabitants (excluding imported cases). The highest incidence rate was observed among infants under one year of age: 11.14 per 100,000 inhabitants, with 69 cases, representing 17.3% of all cases reported in 2024. This rate was higher than that observed in this age group in previous years, linked to the occurrence of several clustered cases in daycare centers.

• 144 cases (30%) were hospitalized, including seven in intensive care. Hospitalizations primarily involved children under 5 years of age and adults over 30 years of age. 66 cases developed complications, 42 of which were pneumonia-related. Nearly half of the reported complications involved adults over 30 years of age. No deaths were reported.

• Among the 300 cases eligible for vaccination (aged ≥ 1 year and born since 1980) with known vaccination status, 64% were not vaccinated against measles according to the recommended schedule, 15% had received one dose, 18% had received two doses, and 3% had been vaccinated without the number of doses received being specified. Seven hospitalizations and three complications were reported among subjects who were properly vaccinated with two doses. The observed proportion of cases vaccinated with two doses is consistent with high vaccine efficacy given the vaccination coverage rates in France.

• A 2.7-fold increase in imported cases was again observed in 2024 (84 imported cases versus 31 cases in 2023), more than half of whom were unvaccinated. These cases originated from 24 different countries and spanned all continents except the Americas. The genotypes identified were B3 and D8. These cases generated transmission chains within France, leading to the occurrence of 13 clusters of varying sizes, ranging from 1 to 52 associated cases. Nearly one-third of the reported cases (157 out of 483) were either imported or linked to an importation, confirming the resumption of measles circulation worldwide and the risk of re-emergence in France.

• Of the 68 cluster cases identified in total, six outbreaks of 5 or more cases were observed in 2024. These outbreaks occurred in schools, family circles, and specific populations (Roma camps), but most notably in several daycare centers, particularly affecting infants under one year of age (69 cases), who are at high risk of severe forms of the disease, including long-term complications. The largest cluster of cases was reported in Auvergne-Rhône-Alpes, with 53 cases of measles reported between January and April 2024.