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,as well as recent outbreaks in the Democratic Republic of the Congo (2022 and 2025). A licensed vaccine exists against Zaire ebolavirus (rVSV-ZEBOV, brand name: Ervebo).
- Sudan ebolavirus, responsible for the 2022—23 and 2025 outbreaks in Uganda, with case-fatality rate of around 30%. It has no licensed medical countermeasures.
- Bundibugyo ebolavirus, which caused an outbreak in the Democratic Republic of the Congo in 2012, and is responsible for the May 2026 outbreak in the DRC and Uganda. It has no licensed vaccines or specific antivirals, and case-fatality remains high. See details for CEPI's Calls for Proposals below.
Marburg virus has a similar clinical presentation to Ebola viruses with severe, and often fatal, haemorrhagic fever. A significant outbreak was reported in Rwanda – the first in the country – in September 2024, with 66 cases and 15 deaths. CEPI played a key role in the epidemic response (see more information below). No licensed medical countermeasures exist to prevent or treat Marburg virus disease.
For a comprehensive list of Filovirus outbreaks please see:
History of Ebola Outbreaks | Ebola | CDC and History of Marburg Outbreaks | Marburg | CDC
Mapping Africa's phase 1 trial capacity for Bundibugyo Ebolavirus vaccines
In response to the Bundibugyo emergency in DRC and Uganda, CEPI has activated the organisation’s highest level of outbreak response to accelerate vaccine R&D and manufacturing readiness in concert with country, regional and global partners. To support this response, CEPI’s Research Preparedness Program sought to identify Phase 1 clinical trial units across the African continent, which could be potential facilities capable of running phase 1 clinical trials of Bundibugyo Ebolavirus vaccine candidates.
In June 2026, CEPI issued a Request For Information (RFI) from clinical research institutions across Africa capable of, and interested, in conducting rigorous, ICH-GCP-compliant phase 1 safety and immunogenicity trials for epidemic vaccine candidates, including against Bundibugyo Ebolavirus. Forty-five responses from 17 countries were received. The information has been analysed and compiled into a Summary Report and a searchable database.
The information presented here does not represent an endorsement or a recommendation for any site. Vaccine developers/sponsors planning clinical trials should conduct their own feasibility assessments and site pre-qualification visits according to their own selection criteria. The report and database can be accessed via the following links:
RFI Summary Report (.PDF) RFI Database (.zip)*
*Please click to download and unzip the file which will then operate as a browser based interactive database
Bundibugyo Virus - Calls for Proposals
Request for Information: Phase 1 Clinical Trial Capacity in Africa for Bundibugyo Ebolavirus Vaccines:
CEPI is requesting information from clinical research institutions across Africa capable of and interested in conducting rigorous, ICH-GCP-compliant Phase I safety and immunogenicity trials for epidemic vaccine candidates, including against Bundibugyo Ebolavirus. This RfI closed on 3 July 2026.
Generation of Evidence to Support BDBV Vaccine R&D Decision Making:
This CfP comprises two distinct workstreams: i) Epidemiology, modelling and analytics; and ii) Immunological and clinical assessment of potential cross-reactive antibodies induced by investigational or licensed vaccines against Zaïre and Sudan (SUDV) Ebola virus in humans. This CfP closed on 26 June 2026.
Accelerated Development of Early-Stage Vaccine Candidates:
CEPI is funding preclinical and/or Phase I proof-of-concept studies of promising Bundibugyo virus vaccine candidates. This CfP closed on 19 June 2026.
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: 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
CEPI has published a Standardized Phase 1 Clinical Trial Protocol Outline for BDBV Vaccine Candidates for multi-developer implementation: Phase 1 BDBV Protocol Outline V1 07JUN26 | CEPI
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)
Gashugi Y, Byiringiro LB, Rukundo J, et al. Marburg virus disease outbreak in Rwanda, 2024: Current efforts and calls to action to mitigate the outbreak in Rwanda. Rwanda Public Health Bulletin, 5(4), 7–15 (December 2024)
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
Horizon Europe – the Framework Programme for Research and Innovation (2021 to 2027) Development of Broadly Protective Filovirus Vaccines: FILOFAX project Call for Proposals | Horizon 2.1 - Health
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
Press Releases on CEPI.net
CEPI-backed Bundibugyo ebolavirus vaccine trial launched by Oxford Vaccine Group | 13 July 2026
CEPI awards Public Health Vaccines US$1.9m to accelerate Bundibugyo ebolavirus vaccine | 9 June 2026
CEPI fast tracks three Bundibugyo ebolavirus vaccine candidates | 1 June 2026