Health authorities in eastern Congo have introduced a new Ebola vaccine produced by an American medical company, aid group MSF said on Thursday, to help combat the world’s second-worst outbreak of the virus on record.

New tools including vaccines have helped contain the outbreak, second only to the 2013-16 West African outbreak that killed more than 11 300, despite public mistrust and conflict affecting the response in parts of the region.

The new vaccine, which has passed clinical trials but has never been tested in a real-world setting, will be administered to 50 000 people in Goma, a city of two million on the Rwandan border, Médecins Sans Frontières (MSF) said in a statement.

The vaccine, which requires two injections eight weeks apart, will be rolled out alongside another manufactured by Merck, which only requires a single shot. The Merck vaccine has been administered to over 250 000 people since the start of the outbreak in August 2018.

Congo’s epidemic has infected over 3 000 people and killed nearly 2 200 people, however, the number of reported new infections has fallen steeply since June.