There’s some good news related to an Ebola crisis that has offered very little up until now. The World Health Organization now predicts there are adequate supplies of an experimental Ebola vaccine to control the outbreak in the Democratic Republic of the Congo.
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That study tested the vaccine in an approach that is being used in the current outbreak, a ring-vaccination strategy. People who have been in contact with a case — and then all of their contacts — are offered vaccine. People on the front lines of the response — health workers, people who conduct safe burials — are also offered the chance to be vaccinated.

Salama said the vaccine efficacy rate in the current outbreak is well above 90 percent. He acknowledged there have been a few infections in people who were vaccinated, but said the number — which he declined to specify — is low. “There are very few breakthrough cases,” he said.
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As of Monday, there have been 689 confirmed and probable infections in this outbreak and 422 deaths.

https://www.statnews.com/2019/01/22/some-needed-good-news-on-ebola-vaccine-supplies-are-expected-to-last/