The Ebola outbreak in West Africa appears to have hit a lull, with Doctors Without Borders reporting
empty beds in clinics that just weeks ago were overflowing with sick patients. Meanwhile, two candidate vaccines are rushing through human trials, with field tests slated to begin in Africa as early as December. Jon Cohen, a staff writer covering the outbreak for Science
magazine, says that despite the vaccines’ success in monkeys, their efficacy in humans is far from guaranteed.