Nearly 5,000 people worldwide have died in the recent Ebola outbreak.
Most of the victims are from countries in West Africa, where medical teams are in a race against time.
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Meanwhile, the largest Ebola testing ever, is happening in Switzerland.
An American company sent a new vaccine there, which the World Health Organization will administer to 120 volunteers.
A vaccine is a specially prepared medicine that improves a persons' immunity to a particular disease.