HMN 2025: How Dengue vaccine gains first major approval

The world’s first single-dose vaccine to prevent dengue fever has been approved for licensure in one of the largest countries affected by the disease, following 16 years of research contributions by scientists at the University of Vermont (UVM) Vaccine Testing Center, in partnership with the U.S. National Institutes of Health (NIH) and the Johns Hopkins Bloomberg School of Public Health (JHSPH).

Dengue is the most common mosquito-borne disease worldwide, with nearly half the world’s population living in places with the risk of dengue. Along with high fever and severe muscle and bone pain, the virus can lead to shock, bleeding, and death.

With more than 100 million cases reported annually, dengue poses a growing risk throughout the globe, including in the United States. Brazil recorded 5.9 million cases of dengue and more than 6,000 deaths in 2024.

There have been recent dengue outbreaks reported in Puerto Rico and the U.S. Virgin Islands, and locally acquired cases in the last year in Florida, California, and Texas.

Vaccine approval and global impact

The new vaccine has now been licensed for use in Brazil under the name Butantan-TV. On November 26, the Instituto Butantan, a biologic research center in São Paulo, announced that the vaccine will be incorporated into Brazil’s national immunization program.

Brazil faced a severe dengue outbreak in 2024, with more than 6.5 million cases and over 5,000 deaths reported. Additional global approvals are anticipated as the vaccine is developed through other pharmaceutical partners including Merck and the Serum Institute of India.

Antiviral medication and clinical trials

In addition to the vaccine approval, a promising new antiviral medication designed to prevent infection and illness in individuals exposed to dengue virus will now advance, thanks to clinical trials at the UVM Vaccine Testing Center and JHSPH. The findings were published in the New England Journal of Medicine (NEJM).

“These milestones represent a turning point in global dengue prevention and treatment,” said UVM Vaccine Testing Center founder Beth Kirkpatrick, M.D., professor and chair of the Department of Microbiology and Molecular Genetics at the Robert Larner, M.D. College of Medicine at the University of Vermont. “We are proud of the role UVM has played in advancing science that will save lives worldwide.”

Kirkpatrick served as principal investigator. Kirkpatrick and colleagues began studying the candidate tetravalent (four-serotype) dengue vaccine in 2009 in collaboration with leaders in the dengue field: JHSPH professor Anna Durbin, M.D., and NIH virologist Steven Whitehead, Ph.D. Whitehead and colleagues at the NIH designed the candidate vaccine.

Since 2009, more than 27 clinical trials have been conducted at UVM and JHSPH to develop this vaccine, yielding many major scientific and immunologic insights.

Details of the antiviral study

At UVM, the new dengue antiviral treatment investigation was led by Kristen Pierce, M.D., co-director of the Vaccine Testing Center and professor of medicine, and by Durbin’s team at JHSPH. About 80 volunteers participated in clinical trials at the two sites.

The volunteers were randomly assigned to receive either the treatment or a placebo prior to receiving a dose of a mild strain of dengue virus.

The study data published in NEJM showed that the treatment, an oral pan-dengue small molecular antiviral called Mosnodenivir, inhibits replication of dengue virus and prevents infection. An oral antiviral drug would be extremely useful during outbreaks and could be utilized by travelers and persons who are not able to receive a vaccine.

Additional Larner College of Medicine investigators leading dengue vaccine and treatment studies include Mary Claire Walsh, PA-C, co-director of the Vaccine Testing Center, immunologist Sean Diehl, Ph.D., associate professor of microbiology and molecular genetics, and an experienced team of clinical research coordinators and laboratory staff.

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