Measles outbreak at the Val Thorens ski station, France, 2019

Abstract

Abstract During the 2019 winter season, a measles outbreak occurred at the Val Thorens ski station in France, in an area frequented by over 300,000 holiday-makers (70% foreigners) and 2,500 seasonal workers. Between 24/01/2019 and 15/04/2019, 55 cases were reported (18 confirmed and 37 clinical). Apart from 5 infected children under 2 years old attending the same nursery, cases were mainly seasonal workers between 19 and 41 years old. Five cases were hospitalised, one with severe pneumonia. Of the 36 cases with known vaccination status, 25 (69%) had not completed 2-dose vaccination. Other confirmed cases in visitors to Val Thorens were reported in neighbouring valleys (n = 3), and in other French regions. One case was reported the French overseas territory Guadeloupe (WHO ‘Americas’ region where measles has been eradicated). British, Belgian, Danish, Dutch and Irish authorities reported 7 cases in people who had stayed in the area. The list of exported cases is non-exhaustive. The regional health agency (ARS) provided increased information on epidemic risk and vaccination recommendations, particularly to health professionals and the town council. Identifying all contacts was difficult because many had occurred with seasonal workers. In addition to the approximately 150 vaccinations carried out by the Val Thorens medical centre from the start of the outbreak, only 41 other people were vaccinated in 5 free vaccination sessions organized in situ by the ARS, and the local medical and immunization centres. The large attendance at the station favoured the outbreak and its extension in France and abroad. Due to low measles vaccine coverage in France (80.3% for 2-dose cover in 2 years in 2017), outbreaks in non-vaccinated and not fully vaccinated populations are increasing, as seen in Val Thorens. Key messages A major measles epidemic occurring in an undervaccinated population in frequent contact with tourists, led to the extension of cases in France and Europe. Despite 5 free in situ vaccination sessions, with the mobilisation of local health professionals, few seasonal workers came to be vaccinated.