Can the Ebola Zaire vaccine stop the Bundibugyo virus?

Author(s): Edward Kenyi

Editor-in-Chief

South Sudan Medical Journal

Email: [email protected] 

The current Ebola outbreak in the Democratic Republic of Congo (DRC) has officially become the fastest on record, with the World Health Organization (WHO) reporting more than 5,200 confirmed cases and 2,600 deaths in the country as of August 12, 2026.[1] Despite the valiant efforts of health workers, community mobilization, and international support, the Bundibugyo virus continues to wreak havoc in the DRC and poses a threat to neighbouring countries.

One public health tool for dealing with outbreaks is vaccination. Ebola vaccine candidates were developed over a long period by different companies, including the Wellcome Trust, Merck, and GlaxoSmithKline. These vaccines were mainly being developed against the dominant Ebola Zaire variant.

During the West Africa outbreak in 2014–2015, a vaccine was rapidly brought into clinical trials in the field and shown to be effective in protecting people against the Ebola Zaire virus. By March 2017, the WHO Strategic Advisory Group of Experts (SAGE) recommended deploying Merck’s Ebola vaccine (VSV-ZEBOV) under the Expanded Access framework. This remained the only vaccine approved and licensed for use against the Ebola Zaire virus.[2] There are no vaccines against the other virus strains.

When the Bundibugyo virus strain outbreak occurred in the DRC, the question was whether the Merck vaccine could be deployed against it. WHO’s position on using the Ebola vaccine Ervebo® during the current Bundibugyo Ebola virus outbreak remained unchanged: at this time, there is not enough evidence to know whether the vaccine works against this virus, and it does not recommend using it to respond to the outbreak.[3]

Things have changed quickly. Reports indicate that the WHO and Africa CDC approved the DRC government’s request to release Ervebo vaccines for use against the Bundibugyo virus in August.[4] As the only available vaccine, Ervebo is being deployed as part of a clinical trial to assess its impact on the Bundibugyo virus and provide evidence of its effectiveness.

Let us welcome this development. As the outbreak seems to continue unabated, every available effort and tool should be deployed to stop it. Maybe the vaccine can at least slow the outbreak and bring some relief to the community.

  1. World Health Organization. Over 5200 cases recorded as Democratic Republic of the Congo crosses 100 days since Ebola outbreak declaration, News Release. WHO. 24 August 2026. https://www.afro.who.int/countries/democratic-republic-of-congo/news/over-5200-cases-recorded-democratic-republic-congocrosses100-days-ebola-outbreak-declaration   
  2. World Health Organization. Ebola Virus Disease Vaccines. Regulation and Prequalification. WHO: Geneva https://www.who.int/teams/regulation-prequalification/eul/ebola-vaccines  
  3. World Health Organization. Ebola vaccines. Questions and answers. 25 June 2026. WHO: Geneva https://www.who.int/news-room/questions-and-answers/item/ebola-vaccines  
  4. World Health Organization. WHO and Africa CDC welcome the allocation of Ebola vaccines to the Democratic Republic of the Congo, News Release. WHO: Geneva/Addis Ababa. 20 August 2026. https://www.who.int/news/item/20-08-2026-who-and-africa-cdc-welcome-the-allocation-of-ebola-vaccines-to-the-democratic-republic-of-the-congo#:~:text=Ervebo%20vaccine%20is%20licensed%20and,release%20of%2070%20000%20doses.