It also now predicts it can 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.
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"As long as there are still Ebola patients, there is the risk that it will continue to go around the region," Paul Stoffels, J&J's chief scientific officer, told reporters.
The initial stage of first-in-human testing with J&J's vaccine is being conducted by experts at the University of Oxford, where 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, where volunteers will receive the vaccine in Kenya, Uganda and Tanzania.
In all, some 300 subjects will be involved in Phase I testing, after which J&J hopes to move rapidly into larger studies, with final-stage Phase III trials planned for the second quarter of 2015.
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 immunization more complicated.
"What we are doing with prime-boost is going for maximal protection, as well as long-term protection," Stoffels said.
Importantly, tests have shown the J&J vaccine can be stored in a normal fridge for several months, rather than needing special freezing, which is difficult in rural Africa.Follow us on Twitter: @CNBCWorld