The first person to receive a new vaccine for the Ebola virus in a trial at the University of Oxford on Wednesday was a healthy British volunteer.
The testing began as Britain announced it would increase aid to Sierra Leone to provide 700 treatment beds over the coming months, with military personnel helping their roll out.
US President Barack Obama this week urged action against the worst ever epidemic of the disease, warning it was "spiralling out of control".
The volunteer is one of 60 who will receive the drug at the University of Oxford in testing that will run alongside similar trials in the United States and could mean a vaccine being produced by the end of the year.
Researchers hope to establish whether the vaccine, which contains genetic material from the Ebola virus, can trigger the immune system to produce enough antibodies to fight off the disease, which has a mortality rate of over 50 percent.
The vaccine specifically targets the Zaire species of Ebola, which has killed 2,461 people out of 4,985 recorded cases in Guinea, Liberia, Senegal and Sierra Leone since the start of the year, according to World Health Organisation (WHO) data.
"The tragic events unfolding in Africa demand an urgent response," professor Adrian Hill, who heads up the research team in Oxford, said last month when the trial was announced.
"We, and all our partners on this project, are optimistic that this candidate vaccine may prove useful against Ebola."
Developed jointly by British company GlaxoSmithKline and the US National Institutes of Health, the vaccine has produced good results in testing on monkeys.
The Jenner Institute in Oxford has been given Ģ2.8 million ($4.6 million, 3.5 million euros) for the testing, which should allow GlaxoSmithKline to produce an additional 10,000 doses of the vaccine during the trial period.
The WHO has said the vaccine could be available from November if it proves safe, although researchers are more cautious and say it would be by the end of the year.
On Wednesday, Britain said that military personnel would help to identify sites for 700 treatment beds, as well as providing and training staff to operate the beds.
"The Ebola epidemic in west Africa is already an unprecedented humanitarian emergency for the affected countries," said Foreign Secretary Philip Hammond.
"If we fail to act now it could become a global catastrophe with disastrous consequences."
The announcement came after the United States said it would send 3,000 military personnel to West Africa to combat the crisis.