Scientists at Oxford University have begun immunising healthy volunteers with a new Ebola vaccine.
In September last year a separate trial of another Ebola vaccine got under way in the city.
This latest trial involves 72 volunteers aged 18-50.
Initial tests in monkeys showed the vaccine, developed by Janssen Pharmaceutical Companies of Johnson and Johnson, gave complete protection against Ebola.
The volunteers in Oxford are the first humans to receive the vaccine.