A passenger diagnosed with measles travelled on the Viking Glory ferry last week, according to the Finnish Institute for Health and Welfare (THL). Despite the diagnosis, health authorities state the risk of onboard transmission remains low as the individual *was* vaccinated against the disease. This suggests the vaccination provided some protection, limiting the potential spread. The THL is currently investigating travel history and potential contacts to contain any further possible infections. Passengers who travelled on the Viking Glory during the relevant period are advised to be vigilant for measles symptoms. This case highlights the importance of vaccination even though breakthrough infections can occur. Further updates will be provided as the investigation progresses.