The EBOVAC3 project aims to assess, through clinical trials in children and adults in Africa, the safety and effectiveness of an Ebola vaccine regimen. As such it will help to improve the world’s preparedness to deal with an Ebola outbreak. The project focuses on the ‘prime-boost’ Ebola vaccine regimen (Ad26.ZEBOV and MVA-BN-Filo), in which patients are first given a dose to prime the immune system, and then a boost dose which is intended to enhance the immune response over time. Building on work carried out under the EBOVAC1 and 2 projects, EBOVAC3 will run clinical trials in children in Sierra Leone, Guinea and the Democratic Republic of Congo. It will also follow up people who participated in earlier clinical trials in Sierra Leone, to assess the safety and efficacy of the vaccine in the longer term. Finally, the project aims to characterise the outbreak preparedness of Sierra Leone, Guinea and the Democratic Republic of Congo.