Compositions and methods are described for generating an improved effective immune response against an immunogen in humans. The enhanced immune response, is obtained by using an MVA vector as a prime, an adenovirus vector as a first boost, and an adenovirus vector as a second boost. The compositions and methods can be used to provide a protective immunity against a disease, such as an infection of one or more subtypes of Ebola and Marburg filoviruses, in humans.