First Human Trial for Marburg Virus Vaccine Reports Success

An experimental vaccine against Marburg virus (MARV), a potential pandemic-causing virus of the Ebola virus family, proved safe and successfully induced an immune response in its first-in-human clinical trial. The finding is groundbreaking as there are no approved vaccines or therapies available for MARV disease so far, aside from supportive care.

Researchers at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, are developing the vaccine. The Lancet recently published the results of the study.

Related Article: The Marburg Virus Strikes Again in Africa, Prompting the World to Stay Alert

Deadly Virus Without a Cure

Marburg is as deadly as another member of the Filoviridae family of viruses, Ebola. Although the disease is rare, the death rate varies between 23 to 90 percent depending on the individual’s constitution, and its highly infectious nature makes it a threat to public health. 

Most patients rapidly become symptomatic and develop hemorrhagic fever, severe headaches, and muscle pains. Within three days, symptoms progress to diarrhea, nausea, vomiting, and extreme blood loss. Death usually occurs within nine days due to severe hemorrhage and multiorgan dysfunction.

Since its emergence in 1967, there have been more than a dozen outbreaks over the past 50 years, most recently emerging last year in Ghana for the very first time. Experts warned that people in conflict areas with weak health infrastructure are at high risk of MARV outbreaks like those found in the Democratic Republic of the Congo and Angola earlier this century. The infection can remain uncontrolled for months or years and could claim hundreds of lives.  

The First Marburg Vaccine to Move into Phase 2 Human Trials

The study tested an experimental MARV vaccine candidate, cAd3-Marburg, which scientists developed at NIAID’s Vaccine Research Center (VRC). Researchers used a modified chimpanzee adenovirus called cAd3. The cAd3 can no longer replicate or infect cells to ensure safety and displays a glycoprotein found on the surface of MARV to induce the host’s natural immune responses against the virus.  

In the Phase 1 human trial, 40 healthy adults enrolled to receive the experimental vaccine. None of the participants who received the lower dose experienced severe adverse reactions after one week. As for the higher dose group, only one participant developed a fever following vaccination, but it resolved the following day. These safety markers mean the vaccine was well-tolerated with no serious adverse effects. More importantly, researchers detected significant immune responses in 95% of subjects, and 70% maintained that response for more than 48 weeks. 

As a result of the promising effects, further trials of the cAd3-Marburg vaccine in Ghana, Kenya, Uganda, and the United States are in the works, and scientists aim to use the cAd3-Marburg virus vaccine in emergency responses to MARV outbreaks someday.  

Author

Nai Ye Yeat

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