The first 300 vials of vaccine for Ebola will make their way to Liberia today on a Brussels Airlines flight.
The vaccine, made by pharmaceutical company GlaxoSmithKline (GSK), has been fast-tracked for development to reflect the seriousness of the situation in West Africa.
ITV News science correspondent Alok Jha reports:
Trials in the UK, US and Mali began in September 2014, in which healthy volunteers were given the vaccine to ensure it had no toxic side-effects.
It normally takes several years and tests on many thousands of people before a vaccine can be approved for general use.
But health authorities asked GSK to make several thousand doses of the vaccine before the initial trial results even came in, so that it could be shipped as soon as possible to the affected areas.
Ebola has ravaged Guinea, Liberia and Sierra Leone in the past year. So far almost 9,000 people have died and 22,000 have become infected.
The GSK vaccine on its way to Liberia is the first to go to any affected country and will be given to healthcare workers who are at greatest risk of contracting the infection.
The material is so fragile that it has to be kept at -80ºC at all times and can only be kept outside for a few minutes at a time.
Made at a facility in Italy, the vaccine was brought to Belgium on Thursday morning for preparation and then onward delivery to Liberia.
The GSK laboratories in Brussels will eventually produce thousands more doses of the vaccine and scientists there are in the process of ramping up their ability to produce it.
The vaccine contains a protein from the Zaire species of the Ebola virus, the strain circulating in West Africa, attached to a harmless chimpanzee virus.
They found that the vaccine caused no serious side effects and triggered immune responses against the Ebola virus, as expected.
But there are still many unknowns about the vaccine. What level of immune response can it create in those who get it?
Is it actually effective at protecting people from infection?
Scientists need to carry out a new phase of their clinical trial to look for answers to these questions, which involves giving the vaccine to thousands of people.
The US National Institutes of Health is expected to announce its intention to start such a trial in the coming days or weeks using the vaccines being delivered to healthcare workers in the affected areas.
That trial is expected to involve around 30,000 people, half of whom will get some kind of vaccine, including the GSK drug.
Other vaccines are also under development for Ebola, including those by Canadian and Russian researchers.
A second trial started in the UK at the start of January of a vaccine made by pharmaceutical company Janssen uses two-step treatment that employs different vaccines for each step.
Results from all of those trials are expected later this year.