Merck Launches Phase 3 Trial for Promising Dengue Vaccine V181

• Merck begins Phase 3 trial for single-dose dengue vaccine V181
• The study aims to assess the safety and efficacy against dengue infection
• V181 could offer a major breakthrough in global dengue prevention

Merck, also known as MSD outside the U.S. and Canada, has initiated its Phase 3 clinical trial, MOBILIZE-1 (V181-005), to evaluate the safety, immunogenicity, and efficacy of its investigational dengue vaccine, V181. This quadrivalent, live attenuated vaccine is designed to protect against all four dengue virus serotypes (DENV-1, DENV-2, DENV-3, DENV-4) with a single dose, regardless of prior dengue exposure.

Recruitment for the trial has started, with the first participants enrolling in Singapore. The study aims to enroll around 12,000 healthy individuals aged 2 to 17 across more than 30 sites in dengue-endemic Asia-Pacific countries, including Indonesia, Malaysia, the Philippines, Singapore, Thailand, and Vietnam.

The MOBILIZE-1 trial is randomized, double-blind, and placebo-controlled. Its primary goals are to assess the vaccine’s safety and its efficacy in preventing symptomatic, virologically confirmed dengue of any severity. Secondary objectives include evaluating its effectiveness against individual serotypes and preventing severe disease, cases with warning signs, and hospitalizations.

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Dengue is a major global health threat, with approximately half the world’s population at risk. It is responsible for an estimated 105 million infections annually, including 50–60 million symptomatic cases and around 29,000 deaths. The disease disproportionately affects tropical and subtropical regions and often leads to economic strain due to healthcare costs and productivity loss.

Merck’s V181 vaccine could offer a critical one-dose solution to reduce the global burden of dengue, especially in vulnerable populations. According to Merck’s Dr. Paula Annunziato, the launch of this trial marks a significant step in advancing prevention strategies against this rapidly spreading mosquito-borne disease. V181 could become an important tool in combating dengue worldwide.