Ebola Virus Disease (EVD) is caused by one of five species of Ebola virus: Bundibugyo; Reston; Sudan; Tai Forest; and Zaire (which is the most fatal species). Several EVD outbreaks have occurred in recent years: in the Democratic Republic of Congo, the Republic of the Congo; Gabon, Sudan, Uganda, and Congo and Zaire. The most recent major outbreak occurred in 2014–2015 in countries of the West Africa subregion, mainly in Guinea, Liberia and Sierra Leone, and to a lesser extent in Mali and Nigeria. It was the largest EVD outbreak to date; 28,646 Ebola cases were reported in the three most affected countries (Guinea, Liberia and Sierra Leone), with 11,323 deaths. A significant proportion of survivors have both short‐ and long‐term sequelae.

In order to facilitate potential submissions as well as the assessment process under the emergency use listing procedure, WHO decided to accept “rolling submissions” whereby vaccine manufacturers can submit data sets as they become available. In March 2017, the working group on EVD vaccines and vaccination, of the WHO Strategic Advisory Group of Experts on Immunization (SAGE), recommended that the use of the rVSVΔG‐ZEBOV‐GP candidate vaccine should be deployed under "expanded access".

ERVEBO: Roadmap for introduction and roll out of a licensed Ebola vaccine

In May 2019, WHO published a roadmap aiming to coordinate partners' actions and contributions to the licensing and roll-out of Merck’s injectable Ebola vaccine (rVSV∆G-ZEBOV-GP, live attenuated) (ERVEBO) in African countries. The vaccine was developed during the 2014–2016 EVD outbreak. The vaccine was tested in European and African countries at the time and used under an expanded access protocol in the Democratic Republic of the Congo.

Based on regulatory evaluation by the European Medicines Agency and the US Food and Drug Administration, WHO expedited prequalification, and coordinated work with countries at risk of Ebola outbreaks, to streamline regulatory licensing of the vaccine for use in those countries.

ERVEBO was prequalified on 12 November 2019. It was the first-ever Ebola vaccine to be prequalified and was prequalified in record time. Prequalification was a critical step towards it licensing, access and roll-out in countries most at risk of Ebola outbreaks. The vaccine has been shown to be effective in protecting people from the Ebola Zaire virus and is recommended by SAGE as part of a broader set of Ebola response tools. 

Zabdeno: Roadmap for introduction roll out of second Ebola vaccine

In February 2020, WHO published a roadmap aiming to coordinate partners’ actions and contributions to the licensing and roll-out of Janssen’s Ebola vaccine (Ad26.ZEBOV, MVA-BN®-Filo) (Zabdeno) in African countries. This second vaccine was developed during the 2014–2016 EVD outbreak. The vaccine was tested in European and African countries at the time. WHO will expedite prequalification and licensing of the vaccine for use in countries at risk of Ebola outbreaks and will coordinate work between those countries’ regulatory authorities and the European Medicines Agency and the US Food and Drug Administration.