GSK's experimental vaccine has already produced promising results in animal studies involving primates and it is now due to enter initial Phase I testing in humans, pending approval from the U.S. Food and Drug Administration.
A company spokeswoman said on Sunday that the trial should get underway "later this year", while GSK's partner the U.S. National Institute of Allergy and Infectious Diseases (NIAID) said in a statement on its website it would start "as early as fall 2014", implying a potential September launch of testing.
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Even if is fast-tracked, however, and emergency procedures are put in place, the new vaccine could not be ready for widespread deployment before 2015 - even assuming it works as well as hoped.
"It is right at the beginning of the development journey and still has a very long way to go," the GSK official said, declining to be drawn on a possible timeline for launch.
The investigational vaccine is based on a chimpanzee adenovirus into which two Ebola genes have been inserted, which means it contains no infectious Ebola virus material. Adenoviruses are best known for causing the common cold.
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Once the vaccine enters a cell and delivers its genetic payload, the two gene inserts produce a protein that generates an immune response in the body - but the adenovirus carrying the genes does not replicate further.
GSK acquired the vaccine after buying Swiss-based biotech company Okairos for 250 million euros ($335 million) last year.
The U.S. NIAID - part of the National Institutes of Health - is also supporting work on other early-stage Ebola vaccines, including one from Johnson & Johnson's Crucell unit that should enter Phase I clinical testing in late 2015 or early 2016.
The Crucell vaccine is designed to give additional protection against Marburg, another severe and highly fatal disease caused by a virus from the same family as Ebola.
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