More than 11 000 people in Guinea participated in a WHO-led trial to develop the world’s first vaccine against Ebola virus disease. The ground-breaking trial, which ended in January 2016, resulted in a vaccine that is highly protective against the deadly virus. The Director-General of WHO, Dr Margaret Chan and the WHO Regional Director for Africa, Dr Matshidiso Moeti visited some of the communities who participated in the vaccine trial in the city of Conakry.