Médecins Sans Frontières (MSF) sent some of its most experienced staff as well as 50 tons of materials to areas affected by the Ebola outbreak on May 23, the agency said. The number of deaths from the outbreak rose to 27 on May 22.

UN health agency workers began administering an experimental vaccine against the Ebola virus on May 21. The UN World Health Organization plans to immunize many of the people thought to have been in contact with recently confirmed patients.

This footage shows the MSF response to the outbreak in Mbandaka in the Democratic Republic of the Congo on May 20. Credit: Médecins Sans Frontières (MSF) via Storyful