News releases

MOBILIZE-1 is the first Phase 3 study being initiated for V181 as part of a planned robust clinical development program and has commenced in Singapore

Study will evaluate a single dose of V181 for the prevention of dengue disease caused by any of the four serotypes of the dengue virus regardless of previous exposure

Singapore, Wednesday, 18 June 2025 – MSD (trade name of Merck & Co., Inc., Rahway, N.J., USA) [NYSE: MRK]), has announced the initiation of the MOBILIZE-1 Phase 3 clinical trial evaluating the safety, immunogenicity and efficacy of a single dose of V181, an investigational quadrivalent vaccine, for the prevention of dengue disease caused by any of the four dengue virus serotypes (DENV-1, DENV-2, DENV-3, and DENV-4), regardless of prior dengue exposure. Recruitment for the trial has begun, and the first participants are now enrolling in Singapore.

“Approximately half of the world’s population live in areas with a risk for dengue, making it a serious public health threat,” said Dr. Paula Annunziato, senior vice president, infectious diseases and vaccines, Global Clinical Development, MSD Research Laboratories. “The initiation of the MOBILIZE-1 study, the first Phase 3 trial in our clinical development program, marks a key milestone in our work to help address this widespread mosquito-borne disease. If successful, V181 could provide an important single-dose option for at risk populations, regardless of previous exposure to dengue, to help reduce the significant burden around the globe.”

“I am pleased that this important Phase 3 trial has commenced in Singapore. We are grateful to the scientific community in Singapore for their commitment to scientific excellence and partnership throughout this journey. Singapore and the surrounding countries in Southeast Asia are areas with a risk for dengue, making it a serious public health threat. Through clinical trials like this, MSD continues to demonstrate its commitment to working in partnership with clinical and non-clinical stakeholders in Singapore and regionally to better understand this disease, develop solutions to address this significant unmet health care need and ultimately, win the fight against dengue,” said Dr. Abdullahi Sheriff, Managing Director, MSD in Singapore, Malaysia & Brunei.

“The progress of V181, which has been developed based on sound immunological principles, has been encouraging. This vaccine could potentially contribute to improved dengue prevention, particularly among the paediatric population in Singapore and beyond. A leader in biomedical research in the region, Singapore’s well-established clinical research infrastructure provides a suitable environment to kick off this pivotal trial. Together with recent developments in vector control strategies, V181 may play a meaningful role in ongoing efforts to tackle dengue,” said Dr. Zhong Youjia, Associate Consultant, Khoo Teck Puat – National University Children’s Medical Institute, National University Hospital, who is one of the investigators for the study in Singapore.

“Singapore is an ideal location to kickstart infectious disease research studies, thanks to leading healthcare institutions with a strong track record in infectious disease research, such as the National Centre for Infectious Diseases (NCID) and the strength of research collaborative networks such as the Singapore Infectious Disease Clinical Research Network (SCRN). The vibrant local research landscape, robustness of the regulatory and ethical bodies governing research, and operational efficiency allows Singapore to be the first country globally to start and successfully recruit for this clinical trial. Dengue is an important disease to study, given the global and local challenges of the infection,” said Assistant Professor Chia Po Ying, Head of National Centre for Infectious Diseases (NCID) Research Office and Consultant, NCID. She is also a principal investigator for this study.

MSD is committed to research and innovation that aims to help protect the millions of people at risk for dengue virus infection and is establishing a program of clinical trials for V181, including conducting trials globally, in places where dengue is a significant health threat. In Singapore, the National University Hospital and Tan Tock Seng Hospital have started recruitment, with a third site at KK Women’s and Children’s Hospital planned.

About MOBILIZE-1 (NCT07013487)

               MOBILIZE-1, also known as V181-005, is a Phase 3, randomized, double-blind, placebo-controlled study evaluating the safety, immunogenicity and efficacy of V181, an investigational vaccine for the prevention of dengue disease. The study aims to enroll approximately 12,000 healthy individuals 2 to 17 years of age who will be randomized to receive either a single dose of V181 or placebo. The study is planned to include more than 30 trial sites in dengue endemic areas in the Asia-Pacific region, including Indonesia, Malaysia, Philippines, Singapore, Thailand and Vietnam. The primary endpoints of the study are safety and efficacy of a single dose of V181 in preventing symptomatic virologically confirmed dengue (VCD) of any severity, due to any of the four dengue serotypes, regardless of prior dengue exposure. The key secondary efficacy endpoint is evaluating a single dose of V181 in preventing symptomatic VCD of any severity due to each of the four dengue serotypes, regardless of prior dengue exposure. Additional secondary endpoints include evaluating a single dose of V181 in preventing symptomatic VCD with warning signs, severe VCD, and hospitalization.

For more information on the trial visit clinicaltrials.gov.

About V181

               V181 is a live attenuated quadrivalent vaccine currently being investigated for the prevention of dengue disease caused by any of the four dengue virus types (DENV-1, DENV-2, DENV-3, and DENV-4). V181 is designed to be a single-dose vaccination and is being studied in individuals to provide protection against dengue, including severe forms, whether the individuals have been previously infected with the dengue virus or had no prior infections.

About Dengue disease

               Dengue disease is one of the fastest growing mosquito-borne diseases that affects not just the health but often the economic stability of communities across the globe. It is a rapidly emerging cause of serious and sometimes debilitating illness in tropical and subtropical countries. With approximately half of the world’s population, or four billion people, at risk for dengue disease, it represents a critical public health challenge. Globally, around 105 million dengue viral infections occur annually, with approximately 50-60 million being symptomatic on average per year. While the majority of infections are uncomplicated, serious illness caused by dengue can be severe and lead to death (on average, ~4-11 million cases result in hospitalizations per year and there is an average annual incidence of ~29,000 dengue-related deaths worldwide). Symptoms of mild dengue fever may include a high fever, a rash and muscle and joint pain. Dengue fever might evolve to severe dengue, formerly known as dengue hemorrhagic fever, which can cause severe bleeding, a sudden drop in blood pressure, and in rare cases death.

About MSD

At MSD, known as Merck & Co., Inc., Rahway, N.J., USA in the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.msd.com  and connect with us on X (formerly Twitter),  LinkedIn and YouTube.

###

MSD Media Contact:

Joseph Khong

joseph.khong@msd.com

65 9832 0060