Johnson & Johnson has started clinical trials of its experimental Ebola vaccine, which uses a booster from Denmark's Bavarian Nordic, making it the third such shot to enter human testing.
In clinical development
The initiation of the Phase I study, which had been expected about now, marks further progress in the race to develop a vaccine against a disease has killed more than 8,000 people in West Africa since last year.
Two other experimental vaccines, one from GlaxoSmithKline and a rival from NewLink and Merck, are already in clinical development.
U.S.-based J&J says it had produced enough vaccine to treat more than 400,000 people, which could be used in large-scale clinical trials by April 2015, and a total of 2 million doses would be available through the course of 2015.
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It also expects to be able to make enough vaccine for 5 million treatments, if required, over a 12- to 18-month period.
Just how much Ebola vaccine will be needed depends on how quickly the epidemic in Liberia, Sierra Leone and Guinea is brought under control and declines. Currently, experts project demand at anywhere between 100,000 and 12 million doses.
'Prime boost' approach
The initial stage of first-in-human testing with J&J's vaccine is being conducted by experts at the University of Oxford, where the first of 72 healthy volunteers will get different regimens combining the vaccine components or placebo.
Additional clinical studies are planned in the United States later this month and soon after in Africa.
The J&J and Bavarian vaccine uses a so-called "prime-boost" approach of giving a first shot to stimulate the immune system, followed by a second booster a few weeks later.
The GSK and NewLink vaccines have been tested initially as single shots, although there is growing debate as to whether two-stage vaccination might be a more strategic option, since it is likely to provide better protection. The downside is that it would make mass immunisation more complicated