Ebola disease is a rare but severe illness that affects humans and other primates and is often fatal. It is caused by a group of viruses known as orthoebolaviruses.  

There are four species of orthoebolaviruses known to cause disease in humans:   

• Ebola virus (EBOV), which causes Ebola virus disease (EVD) 
• Sudan virus (SUDV), which causes Sudan virus disease (SVD) 
• Taï Forest virus, which causes Taï Forest virus disease 
• Bundibugyo virus (BDBV), which causes Bundibugyo virus disease (BVD).  
  

Currently, there is one licensed and WHO-prequalified vaccine, Ervebo®, available for the prevention of EVD, caused by EBOV. Administered as a single dose, Ervebo® is recommended for use during EVD outbreaks. 

The Ervebo® vaccine can be accessed through the International Coordinating Group (ICG) on Vaccine Provision global stockpile. For preventive vaccination of health-care and frontline workers, requests for Ervebo® vaccines can be made through Gavi Preventive Ebola vaccination. 

At present, there are no licensed vaccines for SVD, Taï Forest virus disease, or BVD. However, several candidate vaccines are under development.  

An outbreak of Ebola disease caused by the Bundibugyo virus was declared in the Democratic Republic of Congo and Uganda in 2026. The WHO has classified the event as a Public Health Emergency of International Concern (PHEIC) on 15 May 2026 due to Bundibugyo virus disease severity and potential for international spread.  

WHO does not currently recommend the use of Ervebo® vaccine for outbreaks caused by Bundibugyo virus because there is insufficient evidence that it provides protection against this virus. Vaccination is only one component of a comprehensive Ebola outbreak response, which also includes surveillance, laboratory testing, case management, infection prevention and control measures, safe and dignified burials, and community engagement.  

Previously, WHO declared a PHEIC on 8 August 2014 in response to the West African Ebola outbreak (2014–2016), and again on 17 July 2019 during the Ebola outbreak in the eastern Democratic Republic of the Congo (2018–2020).