Yellow fever (YF) is a viral disease that affects 44 countries in Africa and the Americas. It is estimated that every year approximately 200 000 cases and 30 000 deaths are attributed to YF. The disease is transmitted by mosquitoes. YF can cause severe symptoms and death, yet no specific treatment is available for the disease. The only effective prevention is immunization with the YF vaccine. In addition to the population in endemic countries, international travellers moving to/from these areas are recommended to be vaccinated.