The World Health Organization says it will soon start large-scale testing of an experimental Ebola vaccine in Guinea to see how effective it might be in preventing future outbreaks of the dreaded virus.

In a statement issued on Thursday, the U.N. health agency said the study will be focused in Basse Guinee, the region that currently has the most Ebola cases in the country. Officials will aim to vaccinate people exposed to other cases, who are at risk of developing Ebola. If they agree, officials will immunize them to see if they might be protected. The vaccine being tested was developed by Canada.

If the vaccine is effective, "it will be the first preventive tool against Ebola in history," WHO chief Dr. Margaret Chan said in a statement.