A Phase 4 interventional study of ERVEBO Vaccination in Ebola and Bundibugyo Virus Disease (BVD), sponsored by Epicentre. Recruiting at 1 site in Democratic Republic of the Congo. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-29.
Sponsored by Epicentre · Phase 4, Interventional, and Prevention
The BRAVO study (Bundibugyo: Respondre Avec la Vaccination, "On est ensemble") was developed in response to the 2026 Bundibugyo virus disease (BVD) outbreak in the Democratic Republic of the Congo (DRC). The study focuses on frontline workers (FLWs), who are at increased risk of infection because of their involvement in patient care, outbreak response activities, and contact with affected communities. Protecting this population is critical for maintaining healthcare services and strengthening outbreak control efforts.
Currently, there is no licensed vaccine specifically targeting Bundibugyo virus (BDBV) for broad use. However, ERVEBO®, a vaccine licensed against Zaire ebolavirus, is available and has demonstrated a favorable safety profile. Although preclinical and immunological evidence suggests that ERVEBO® may provide some degree of cross-protection against BDBV, the extent of protection remains uncertain. BRAVO therefore aims both to support rapid vaccination of frontline workers during the outbreak and to generate evidence that can inform future vaccine policy and preparedness strategies.
BRAVO is designed as a phased study embedded within the public health response. The study population includes adults aged 18 years and older working in Ebola treatment centers, healthcare facilities, or community-based outbreak response activities in affected areas. Both clinical and non-clinical personnel may participate if their duties place them at risk of exposure to infected individuals, infectious materials, or affected communities.
The study consists of three steps:
Step A: Immediate deployment and evaluation of ERVEBO® during the outbreak. Step B: Potential future evaluation of heterologous prime-boost vaccination strategies if additional vaccines become available and remain relevant.
Step C: Potential contribution to evaluation of future Bundibugyo virus-specific vaccines.
The primary focus of the current study is Step A, which is a prospective cohort study conducted under real-world outbreak conditions. The main objective is to assess the effectiveness of ERVEBO® vaccination against Bundibugyo virus disease, severe disease outcomes, and death. The primary effectiveness endpoint is whether vaccination reduces case fatality among laboratory-confirmed BVD cases hospitalized in Ebola treatment facilities.
Secondary objectives include evaluating whether vaccination reduces:
BVD-related mortality in the cohort, Incidence of symptomatic laboratory-confirmed BVD, Indicators of severe disease among confirmed cases.
Safety is also an important component of the study. Serious adverse events occurring within one month after vaccination will be documented, and pregnancy outcomes among enrolled pregnant participants will be monitored.
Participants may be enrolled regardless of vaccination status, allowing comparisons between vaccinated and unvaccinated frontline workers as vaccine deployment progresses according to operational feasibility and risk prioritization. Written informed consent will be obtained before enrollment and vaccination. The consent process will clearly communicate that protection against Bundibugyo virus has not been established and that additional vaccine options may become available in the future.
Participants will generally be followed for six months after enrollment, or until the end of the outbreak if it occurs earlier. Pregnant participants will be followed through pregnancy outcomes. An additional component within Ebola treatment centers will collect information on frontline workers presenting with symptoms compatible with BVD, supporting supplementary analyses of vaccine effectiveness using routinely collected clinical and laboratory data.
Step A aims to vaccinate approximately 20,000 frontline workers during the first six months of implementation. Based on projected outbreak assumptions, the study may generate sufficient confirmed BVD cases to provide meaningful estimates of vaccine effectiveness, particularly regarding protection against death.
Beyond evaluating the immediate impact of vaccination, BRAVO is expected to strengthen outbreak preparedness by establishing systems for vaccination delivery, pharmacovigilance, data collection, and participant communication. The study is designed to provide decision-relevant evidence during the outbreak rather than after it, helping guide future recommendations for Bundibugyo virus vaccine strategies.
Enrollment and vaccination are planned from September through December 2026, with follow-up continuing through June 2027. Final analysis and reporting are expected in September 2027.
BRAVO (Bundibugyo: Respondre Avec la Vaccination, "On est ensemble") is a phased study conducted during the 2026 Bundibugyo virus disease (BVD) outbreak in the Democratic Republic of the Congo. The study aims to evaluate the effectiveness and safety of ERVEBO® vaccination among frontline workers (FLWs) and to generate evidence to support public health decision-making for BVD prevention and outbreak response.
Frontline workers are at increased risk of Bundibugyo virus exposure through clinical care, outbreak response activities, and interactions with affected communities. Although no vaccine specifically licensed for Bundibugyo virus is currently available for broad use, ERVEBO®, a vaccine licensed against Zaire ebolavirus, is available and may provide cross-reactive protection against Bundibugyo virus. The extent of such protection is not yet established.
The study population includes adults aged 18 years and older working in healthcare facilities, Ebola treatment centers, laboratories, or community-based outbreak response activities within affected areas. Both clinical and non-clinical personnel may be eligible if their roles involve potential exposure to patients, infectious materials, or affected communities.
The study consists of three planned phases. Step A, the primary focus of the current outbreak response, evaluates the deployment of ERVEBO® under routine operational conditions. Participants may be enrolled regardless of vaccination status, allowing comparison of outcomes between vaccinated and unvaccinated frontline workers over time.
The primary objective of Step A is to assess the effectiveness of ERVEBO® vaccination in reducing mortality among laboratory-confirmed BVD cases. Secondary objectives include evaluating the impact of vaccination on BVD-related mortality, incidence of symptomatic laboratory-confirmed disease, and indicators of severe disease among confirmed cases. Safety assessments include monitoring serious adverse events for one month following vaccination and documenting pregnancy outcomes among enrolled pregnant participants.
Participants will generally be followed for six months after enrollment or until the end of the outbreak, whichever occurs first. If the outbreak continues beyond the planned follow-up period, follow-up may be extended. Data collected during routine outbreak response activities, including information from Ebola treatment facilities, may support additional analyses of vaccine effectiveness among symptomatic frontline workers tested for BVD.
The study is also intended to strengthen operational preparedness by supporting vaccination delivery systems, pharmacovigilance activities, outbreak data collection, and risk communication processes. Future protocol amendments may allow evaluation of heterologous prime-boost vaccination strategies (Step B) or participation in assessments of future Bundibugyo virus-specific vaccines (Step C) if such vaccines become available. The study is expected to provide timely evidence to inform interim and long-term vaccination strategies for Bundibugyo virus disease.
104 studies on the registry are indexed under Hemorrhagic Fever, Ebola; 13 are open to participants now.
This study's planned enrollment of 20,000 is above the median of 94 across 81 interventional studies indexed under Hemorrhagic Fever, Ebola.
Browse Hemorrhagic Fever, Ebola studies →Epicentre is the lead sponsor of 49 studies on the registry; 6 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Eligibility criteria for enrolment in the BRAVO cohort
Inclusion criteria:
The following FLWs will be eligible for enrolment in the study:
Currently working, or holding a signed work assignment to work, in the following settings within BVD-affected study areas:
Exclusion criteria :
There are no exclusion criteria to participate in the BRAVO cohort. If a FLW chooses to not receive the ERVEBO vaccine, they can be enrolled as part of the control group.
To be part of the vaccinated group, additional criteria apply as below:
Eligibility criteria specific to vaccination
Inclusion criteria:
Exclusion criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
The number of CD4 cells, a type of white blood cell, in a given amount of blood. It is used to follow how well the immune system is doing in HIV.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CD4 count
The number of CD4 cells, a type of white blood cell, in a given amount of blood. It is used to follow how well the immune system is doing in HIV.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Frontline workers who do not receive ERVEBO® during the observation period and are followed for outcome assessment.
Frontline workers who receive ERVEBO® as part of the outbreak vaccination program
Biological: ERVEBO Vaccination
Frontline workers who receive ERVEBO® as part of the outbreak vaccination program
Case fatality among laboratory-confirmed BVD cases hospitalized in Ebola health facilities
Effectiveness of ERVEBO® in reducing case fatality among laboratory-confirmed Bundibugyo virus disease (BVD) cases hospitalized in Ebola health facilities.
Time frame: Up to 6 months after enrolment
Incidence of BVD-attributable death
Incidence of BVD-attributable death among enrolled frontline workers during follow-up, including deaths occurring in Ebola health facilities and in the community
Time frame: Up to 6 months after enrollment
Cumulative incidence of laboratory-confirmed BVD
Cumulative incidence of symptomatic laboratory-confirmed BVD among vaccinated versus unvaccinated frontline workers.
Time frame: Up to 6 months
Test-negative vaccine effectiveness
Proportion of vaccinated frontline workers among laboratory-confirmed BVD cases compared with BVD-negative symptomatic frontline workers presenting to Ebola health facilities.
Time frame: Up to 12 months
Severe disease among confirmed BVD cases
Proportion of laboratory-confirmed BVD cases presenting with high viral load at admission, measured by low PCR cycle-threshold (Ct) value, a marker of severe disease and mortality.
Time frame: Day 1
Serious adverse events (SAEs)
Proportion of vaccinated participants experiencing at least one serious adverse event (SAE) during the safety follow-up period.
Time frame: 1 month after vaccination
Pregnancy and delivery outcomes among pregnant participants receiving ERVEBO®
Proportion of pregnancies with at least one adverse pregnancy or delivery outcome among pregnant participants receiving ERVEBO®. Adverse outcomes include spontaneous abortion, stillbirth, elective termination, congenital anomalies, neonatal death and maternal death.
Time frame: 2 months after vaccination
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Epicentre