No vaccine for Marburg virus is currently approved by the FDA or any other major regulatory agency. However, a leading candidate has shown strong results in early human trials and was deployed during a real outbreak in Rwanda in late 2024. The gap between “no approved vaccine” and “nothing available” is narrowing fast.
The Most Advanced Candidate
The frontrunner is a vaccine called cAd3-Marburg, developed through a partnership involving the Sabin Vaccine Institute. It uses a modified chimpanzee cold virus (adenovirus) as a delivery vehicle to carry a key protein from the Marburg virus surface into the body. Your immune system learns to recognize that protein without ever being exposed to actual Marburg virus. It’s a single-dose shot given in the arm, which is a significant practical advantage for outbreak settings where follow-up visits are difficult.
This vaccine completed a Phase 1 trial in the United States between 2018 and 2019, enrolling 40 healthy adults aged 18 to 50. No serious side effects related to the vaccine occurred. The most common reactions were injection site pain (68% of participants), fatigue (45%), headache (43%), and muscle aches (35%), all mild to moderate. These are similar to what people experience after a flu shot or COVID vaccine. The trial confirmed the vaccine triggered a measurable immune response at both dose levels tested.
A Phase 2 trial, which is larger and placebo-controlled with an estimated 200 participants, is now active in Uganda and Kenya. No safety concerns have been reported from that trial either.
Real-World Use in Rwanda
When a Marburg outbreak hit Rwanda in October 2024, the vaccine moved from the lab to the field. The Sabin Vaccine Institute shipped 700 doses to Rwanda on October 5, followed by roughly 1,000 more doses a week later. Under a rapid-response clinical trial agreement with the Rwanda Biomedical Centre, approximately 700 high-risk adults were vaccinated across six clinical trial sites. Healthcare workers, who face the highest risk of infection during filovirus outbreaks, were first in line.
This kind of deployment happens under special regulatory frameworks that allow experimental vaccines to be used during public health emergencies, even before full approval. It’s the same general approach used with Ebola vaccines during earlier outbreaks in West Africa and the Democratic Republic of the Congo.
Why It’s Taking So Long
Marburg outbreaks are rare and unpredictable. The virus has caused fewer than 20 known outbreaks since it was first identified in 1967, and most have been small. That creates a fundamental problem for vaccine development: you can’t run a traditional large-scale efficacy trial if there aren’t enough cases to measure whether the vaccine works in real-world conditions. Developers have to rely on immune response data from healthy volunteers combined with animal studies, then wait for outbreaks to test the vaccine in the field.
Manufacturing presents its own challenges. Because outbreaks are sporadic, mass vaccination campaigns aren’t practical the way they are for diseases like measles or COVID-19. Instead, the strategy is to stockpile vaccines for rapid deployment when an outbreak begins. That requires formulations with a long shelf life. The U.S. Biomedical Advanced Research and Development Authority (BARDA) is working toward a freeze-dried version of future vaccines that would last much longer in storage and reduce the need for cold-chain refrigeration during transport to remote areas.
Other Candidates in the Pipeline
The cAd3-Marburg vaccine is the most advanced, but it’s not alone. The WHO convened a Technical Advisory Group specifically to evaluate and prioritize Marburg vaccine candidates. As of November 2025, at least four candidates had been formally reviewed, with the two most advanced receiving updated assessments. The group evaluates each candidate on safety, potential efficacy, available evidence, and the practical question of how many doses could actually be manufactured and delivered.
BARDA has also signaled interest in next-generation approaches, including needle-free delivery systems and even 3D-printed or on-demand manufacturing that could produce vaccines closer to where outbreaks occur, cutting out weeks of shipping and logistics.
Ebola Vaccines Don’t Cover Marburg
Marburg and Ebola are closely related viruses in the same family (filoviruses), and they cause similar hemorrhagic fever illnesses. But the existing Ebola vaccine, Ervebo, does not protect against Marburg. Merck, the manufacturer, states explicitly that Ervebo does not work against other ebolavirus species or Marburg. The surface proteins the immune system targets are different enough that a separate vaccine is needed.
What This Means Right Now
If you’re traveling to regions where Marburg has been reported, there is currently no vaccine you can get at a pharmacy or travel clinic. The experimental vaccine is only available through clinical trials or emergency outbreak-response programs. People in affected areas have to rely on the same infection-control measures that have contained past outbreaks: avoiding contact with infected individuals and their bodily fluids, staying away from caves where fruit bats (the natural reservoir of the virus) roost, and rigorous protective equipment for healthcare workers.
The path from Phase 2 trials to full regulatory approval depends partly on whether future outbreaks provide enough real-world data to demonstrate efficacy. Given the Rwanda deployment and ongoing trials, an approved Marburg vaccine is closer than it has ever been, but no timeline for licensure has been publicly announced.