The World Health Organization has sent the first 4,000 doses of an Ebola vaccine to the Democratic Republic of the Congo.

Officials hope the vaccine, developed by Merck, can contain the latest outbreak, which is believed to have killed 20 people since April, Reuters news agency reports.

The experimental vaccine was shown to be effective during limited trials in West Africa during the 2014-2016 Ebola outbreak, which killed more than 11,000 people.