An Ebola vaccine provided 100% protection in a field trial in hard hit Guinea, researchers and officials said Friday, mooting “the beginning of the end” of the killer West African outbreak. “The world is on the verge of an effective Ebola vaccine,” the World Health Organisation (WHO) said, hailing the results from the first efficacy test of the VSV-ZEBOV vaccine among people living in a high-danger zone. “This is an extremely promising development,” added WHO chief Margaret Chan. “An effective vaccine will be another very important tool for both current and future Ebola outbreaks.” About 28,000 people have been infected in Guinea, Sierra Leone and Liberia in the worst Ebola outbreak in history, according to the WHO, and more than 11,000 have died. VSV-ZEBOV may become the first licensed vaccine against the disease for which there is also no approved treatment or cure. The trial showed that the vaccine “offers 100% protection against Ebola after roughly one week,” said researcher Sven Trelle from the University of Bern. The test, backed by drug firm Merck, saw 4,123 high risk people vaccinated immediately after someone close to them fell ill with Ebola. None of the vaccinated group caught the virus, according to study results published in The Lancet medical journal. A second comparison group of 3,528 people received the vaccine only three weeks after potential exposure. Sixteen of them contracted the virus, said the study, but by day six after immunisation, the remainder of this group was also fully protected. Disease experts welcomed the result.