The response to trying to find an Ebola vaccine is one of the fastest to any epidemic ever seen, the professor who is leading the British trial said.
Professor Adrian Hill told ITV News it was "totally unprecedented" and added: "I've never seen anything happen so quickly before in terms of getting a vaccine trial started.
"We've done in days what might take months, or certainly weeks, so it's been fantastic to see that in a month we've gone from deciding to do this to actually vaccinating people."
The professor warned "lots could go wrong" but said so far he believed the vaccine was safe.
The current trials are expected to commence in December after being tested on 140 people both in Britain and in Africa.
If the results show it has been successful, stockpiles of the drug will then be distributed to those most in need.
As it reaches seven months since the Ebola outbreak started we take a look at the timeline of events leading up to the spread of the virus.
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