The Ebola outbreak killed more than 11,300 people, mostly in West Africa.
Sierra Leone was first declared Ebola-free on 7 November 2015. Almost 4,000 people had died from the virus in that country since the end of 2013.
WHO declares Ebola transmission over, when a country goes through two incubation periods, each of three weeks, without a new case emerging.
Picture source: Cynthia Goldsmith via Wikimedia