An experimental ebola vaccine will be injected into the first human volunteer in Oxford later today.
Around 60 healthy people are expected to be given doses of the vaccine as part of the clinical trial at the University of Oxford.
The vaccine is made from a harmless chimpanzee virus that has been genetically modified to carry a benign payload of ebola DNA.
The genetic material will make a single ebola protein in the body – not enough to cause the disease, but enough to prime the immune system to attack the virus in future.
The volunteers will be given different doses and then monitored for side effects and their immune response.
Trials in monkeys have shown the vaccine is 100% effective in the first month, with some protection remaining 10 months later.