IAVI Initiates First-in-Human Trial of Single-Dose Marburg Virus Vaccine Candidate
Key Insights
IAVI (search) has begun dosing participants in a Phase 1 clinical trial of its investigational rVSV∆G-MARV-GP (search) vaccine candidate, marking the first human testing of a Marburg virus (search) vaccine.
The vaccine candidate demonstrated 100% protection against lethal Marburg virus (search) challenge in nonclinical studies, using the same viral vector platform as Merck (search)'s approved Ebola vaccine ERVEBO.
Marburg virus disease (search) has an average case-fatality rate of about 65% with no approved vaccines currently available, and outbreaks appear to be increasing in frequency with three occurring in sub-Saharan Africa in the past 18 months.
IAVI (search), a global nonprofit biomedical research organization, has initiated dosing in the first-in-human Phase 1 clinical trial of its investigational Marburg virus (search) vaccine candidate. The study, designated IAVI C104 (NCT07425821), represents a critical milestone in developing countermeasures against a deadly pathogen with no approved vaccines.
The trial is evaluating the safety and immunogenicity of IAVI (search)'s rVSV∆G-MARV-GP (search) vaccine candidate, which demonstrated remarkable efficacy in preclinical testing. A single intramuscular vaccination protected 100% of test subjects against lethal challenge with Marburg virus (search) in nonclinical studies.
"IAVI (search) C104 represents an important step toward generating the data needed for eventual regulatory approval of IAVI's Marburg vaccine candidate," said Mark Feinberg, M.D., Ph.D., president and CEO of IAVI. "In parallel with this trial, we will continue accelerating efforts toward the availability of candidate vaccine doses for evaluation during and ahead of Marburg outbreaks in sub-Saharan Africa with key collaborators."
Trial Design and Objectives
The Phase 1 study is designed as a placebo-controlled, randomized, and observer-blind trial taking place at several U.S. locations. Approximately 112 healthy adults will be enrolled and followed for six months after vaccination to monitor participant safety and evaluate immune responses using assays developed by IAVI (search) scientists.
The investigational vaccine will be administered intramuscularly at four different dosage levels, allowing researchers to determine the optimal dose for future development. The trial's primary focus is establishing safety parameters and measuring immunogenicity of the vaccine candidate in humans.
Addressing an Urgent Medical Need
Marburg virus disease (search) presents a significant global health threat with devastating consequences. The disease has an average case-fatality rate of about 65%, though some outbreaks have recorded fatality rates as high as 80-90%. The largest outbreak to date occurred in Angola during 2004-05, resulting in 252 cases and 227 deaths.
The frequency of Marburg virus disease (search) outbreaks appears to be increasing, with concerning epidemiological trends emerging across sub-Saharan Africa. Of 17 outbreaks reported since the virus was discovered approximately 60 years ago, almost half have occurred in the last decade, and three have occurred in the past 18 months alone.
The most recent outbreak caused 14 cases and 9 deaths in Ethiopia, beginning in October 2025 and declared over in January 2026. The disease is also emerging in previously unaffected countries, with recent outbreaks in Rwanda and Ethiopia serving as key examples of this geographic expansion.
The Department of Homeland Security has determined that Marburg virus (search) presents a material threat to U.S. national security and is classified as a Public Health Emergency Medical Countermeasures Enterprise high-priority threat.
Proven Platform Technology
The Marburg vaccine candidate utilizes the same recombinant vesicular stomatitis virus (rVSV) viral vector platform as ERVEBO, Merck (search)'s single-dose Ebola virus vaccine, which is licensed in many countries including by the U.S. FDA. ERVEBO has been used extensively to vaccinate adults and children during Ebola outbreaks, demonstrating the platform's real-world effectiveness.
Single-dose vaccines are particularly valuable in outbreak situations because they enable rapid protection of at-risk populations without the logistical challenges associated with multidose follow-up regimens. This characteristic makes the rVSV platform especially suited for emergency response scenarios.
Expanding Portfolio of Emerging Disease Vaccines
The rVSV platform serves as the foundation for IAVI (search)'s growing portfolio of emerging infectious disease vaccine candidates. Beyond the Marburg vaccine candidate, IAVI's rVSV-based portfolio includes a Sudan virus vaccine candidate supported by BARDA (search), a Lassa fever virus vaccine candidate currently in Phase 2a trials supported by the Coalition for Epidemic Preparedness Innovations and the European & Developing Countries Clinical Trials Partnership, and a Crimean Congo hemorrhagic fever virus vaccine candidate.
Using a shared viral vector platform streamlines vaccine development by enabling application of existing knowledge, clinical data, and manufacturing processes across multiple candidates. This approach has the potential to significantly accelerate response timelines during outbreaks while reducing costs and operational complexity.
Much of the research and development on IAVI (search)'s rVSV platform is performed at the IAVI Vaccine Design and Development Lab in Jersey City, New Jersey. Since its founding in 2008, the facility has become one of the world's leading viral vector vaccine research and development laboratories, known for innovation and generation of novel vaccine design concepts.
IAVI (search) holds a nonexclusive license to the rVSV vaccine candidates from the Public Health Agency of Canada, where the vector was originally developed by scientists at the National Microbiology Laboratory.
Funding and Support
The trial is supported by federal funds from the U.S. Department of Health and Human Services, Administration for Strategic Preparedness and Response, and Biomedical Advanced Research and Development Authority (BARDA (search)) under contract number 75A50121C00077. The Defense Threat Reduction Agency of the U.S. Department of War supported preclinical work on the vaccine candidate.
Additional funders supporting the development of IAVI (search)'s rVSV-vectored vaccine candidates include the Gates Foundation, the Government of Canada, the Danish Ministry of Foreign Affairs, the Government of Japan, the Irish Department of Foreign Affairs and Trade, the Netherlands Ministry of Foreign Affairs, the Norwegian Agency for Development Cooperation, the U.K Department for International Development, the U.S. National Institutes of Health, and the former United States Agency for International Development.