Greta Van Susteren went inside an Ebola vaccine testing lab at Walter Reed Army Institute of Research, where the first testing on humans has just begun.

The vaccine has been 100 percent successful on animals, though that won’t necessarily be the case with humans. Now, 39 healthy volunteers are partaking in the study.

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Col. Stephen Thomas, deputy commander of Walter Reed Army Institute of Research, said animal testing can inform decision making, but the only way to know if the vaccine will be effective is through trials in humans and in places where the disease is endemic.

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