An Ebola vaccine provided 100-percent protection in a field trial in hard-hit Guinea, researchers and officials said Friday, hopeful of "the beginning of the end" of the killer West African outbreak.

The world was "on the verge of an effective Ebola vaccine," the World Health Organization (WHO) said, hailing the results from the first efficacy test of the VSV-ZEBOV vaccine among people living in a high-danger zone.