The first study of two separate vaccines against the Ebola virus has found that they can both protect against the haemorrhagic fever for at least a year.
The research, published in the New England Journal of Medicine, was conducted in Liberia and involved 1,500 patients.
Those given the vaccines successfully created a powerful antibody response for a year.
The trial suggests that both vaccines could be used to save lives in any future epidemic of the disease.
Ebola killed more than 11,000 people in Liberia, Sierra Leone and Guinea in an outbreak in 2014-15.