Filoviruses, named after their ‘filamentous’ or thread-like appearance, are associated with haemorrhagic fevers in humans. They include Ebola and Marburg viruses, which have caused devastating epidemics with high case-fatality rates in Africa. Three Ebolavirus species have been associated with outbreaks in humans:

  • Zaire ebolavirus (also known as Zaire virus), responsible for the 2014 West Africa Ebola outbreak, against which a licensed vaccine exists (rVSV-ZEBOV).
  • Sudan ebolavirus, responsible for the 2022—23 outbreak in Uganda, has no licensed medical countermeasures.
  • Bundibugyo ebolavirus, which is causing an outbreak in the Democratic Republic of the Congo in mid-2026, also has no licensed vaccines or specific antivirals. See the World Health Organization Disease Outbreak News (17 May 2026): Bundibugyo Virus Disease, the Democratic Republic of the Congo and Uganda

Marburg virus has a similar clinical presentation to Ebola viruses with severe, and often fatal, haemorrhagic fever. No licensed medical countermeasures exist to prevent or treat Marburg virus disease.

Find out more about filovrisues here: The Filoviruses on CEPI.net

CEPI's Response to Rwanda's 2024 Marburg virus outbreak

In September 2024, Rwanda reported a Marburg virus disease outbreak. Sixty-six patients were eventually confirmed to have MVD, of whom 51 were healthcare workers. Fifteen patients died of MVD (1). During the response, remdesivir (a broad-spectrum antiviral) and the monoclonal antibody MBP091 were used under expanded access and clinical trial protocols. In addition, 1,710 frontline workers and high-risk contacts received the chimpanzee adenovirus 3–vectored vaccine ChAd3-MARV under emergency use authorisation in a phase II clinical trial (2). This emergency trial, supported by CEPI, began within 10 days of the declaration of the outbreak. The swift combination of responses resulted in a rapid decline of cases following the initial peak.

Read more here: Innovations for impact/preparedness in practice: Rwanda record breaking Marburg response

References: (1) World Health Organization. Disease Outbreak News – Marburg virus disease – Rwanda. 2024.   (2) Nsanzimana S. et al. Marburg Virus Disease in Rwanda, 2024 - Public Health and Clinical Responses. New England Journal of Medicine. 2025 Sep 11;393(10):983-993.

Resources and Publications 

Nsanzimana S, Bigirimana N, Hatchett R, et al. How Rwanda mounted a research response with an investigational vaccine just ten days into a Marburg outbreak. NPJ Vaccines 10(1):178 (August 2025)

Watson-Jones D, Kavunga-Membo H, Grais RF, et al. Protocol for a phase 3 trial to evaluate the effectiveness and safety of a heterologous, two-dose vaccine for Ebola virus disease in the Democratic Republic of the Congo. BMJ Open 12(3) March 2022

SPEAC releases updated Adverse Events of Special Interest (AESI) list for Marburg virus disease to support vaccine safety preparedness and clinical study planning: Updated AESI List for Marburg | SPEAC