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Single-Dose Dengue Vaccine Provides Nearly 80% Protection

A person wearing gloves drawing up a vaccine into a syringe.
Credit: Mufid Majnun/Unsplash
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A single-dose vaccine protects nearly 80% of people not previously infected with dengue, according to researchers from the Butantan Institute in Brazil.

Results from a Phase 3 clinical trial show that the vaccine is safe and effective for those aged 2–59 regardless of whether they have previously been infected with dengue.

Expanding dengue vaccine options

Nearly half of the world’s population live in areas where they are at risk of infection with dengue virus. Symptoms of dengue include fever, nausea, vomiting, rashes as well as aches and pains.

Most cases are mild, but around 1 in 20 of those who experience symptoms can develop potentially life-threatening “severe dengue”. Over 6 million cases of dengue were reported across 92 countries/territories in 2023 with at least 6,000 deaths.

However, there are no treatments specifically designed for the disease. Several countries have approved vaccines, but these require several doses, are approved for specific age ranges and may be recommended only for those previously exposed to the virus.

The current study, published in The New England Journal of Medicine, reports the results from a Phase 3 clinical trial of Butantan–Dengue Vaccine (Butantan-DV). This vaccine was safe and effective with a single dose and protected a wide age range regardless of previous infection.

Single dose provides protection

The study reported results from the first two years of the Phase 3 clinical trial. This involved 16,235 participants in 13 states in Brazil, where dengue is considered hyperendemic.

Endemic vs hyperendemic

A disease is classed as endemic when it is consistently present in a specific region or location. An endemic disease can become hyperendemic if it has a high incidence or prevalence.

Of these participants, 10,259 received the vaccine and 5,976 received a placebo. The vaccine was 80.1% effective for participants aged 2–6, 77.8% effective for 7–17 years and 90% effective for those aged 18–59.

Furthermore, the vaccine was 79.6% effective in those with no evidence of previous dengue infection, and 89.2% effective in those who had previous infection.

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The majority of side effects were classed as mild to moderate and included symptoms such as pain at the injection site, headache and fatigue. Side effects classed as severe occurred in less than 0.1% of those vaccinated, all of whom recovered afterward.

Continued follow-up

The development of a single-dose dengue vaccine also provides logistical and economic benefits, as it could provide rapid protection during outbreaks as well as for travelers from places where the disease is not endemic.

“Publication of the article in the world’s leading medical journal attests to the rigor and quality of the work done by researchers at 16 Brazilian centers located in all 5 regions of the country, and coordinated by [the] Butantan Institute,” said Dr. Esper Kallás, an associate professor at the University of Sao Paulo and lead author of the study. “In June, we’ll complete the five-year follow-up period. Once the data has been consolidated, we’ll know how long the protection induced by the vaccine will last.”

“If all goes well, we’ll win definitive approval for the vaccine in 2025. We already have the infrastructure to produce it at [the] Butantan Institute, although it can still be perfected. After all, it’s tetravalent, corresponding to four vaccines in one,” he added.

Reference: Kallás EG, Cintra MAT, Moreira JA, et al. Live, attenuated, tetravalent Butantan–Dengue vaccine in children and adults. NEJM. 2024;390(5):397-408. doi: 10.1056/NEJMoa2301790

This article is a rework of a press release issued by Agencia FAPESP. Material has been edited for length and content.