Inclusion Criteria:  Aged 18 to 45 years on the day of inclusion Participant signed informed consent Residing in Switzerland  Exclusion Criteria:  Participant is pregnant, lactating, or of childbearing potential Participation in the 4 weeks preceding the first trial vaccination or planned participation during the present trial period in another clinical trial investigating a vaccine, drug, medical device, or medical procedure Receipt of any vaccine in the 4 weeks preceding the first trial vaccination (excepting influenza vaccination, which may be received up to 2 weeks before first study vaccine) or planned receipt of any vaccine in the 4 weeks following each trial vaccination. Previous vaccination against Japanese encephalitis (JE), Yellow Fever (YF), or any dengue virus vaccine (monovalent or tetravalent) at any time in the past with either a trial vaccine or another vaccine (commercial or investigational) based on medical history Self-reported or documented history of flavivirus (FV) infection (e.g. DENV, YF, WNV, JE, TBE), confirmed either clinically or serologically Receipt of immunoglobulins, blood or blood-derived products in the past 3 months Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy Self-reported or documented seropositivity for human immunodeficiency virus (HIV), hepatitis B natural infection (HBcAb positive serology), or hepatitis C Previous residence for more than 12 months in, or travel in the last 30 days to FV-endemic regions (excluding TBE and WNV) At high risk for dengue infection during the trial Known systemic hypersensitivity to any of the vaccine components (e.g. gold), or history of a life-threatening reaction to vaccines, or to a vaccine containing any of the same substances Current alcohol abuse or drug addiction (reported or suspected) Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion Thrombocytopenia or any coagulation disorder Identified as an Investigator or employee of the Investigator or study centre with direct involvement in the proposed study, or identified as an immediate family member (i.e., parent, spouse, natural or adopted child) of the Investigator or employee with direct involvement in the proposed study (i.e. in the employment of the Tropivac clinic or DFRI unit at Unisanté). Refusal to be informed in the event that relevant results concerning the participant's health are revealed.  The following events constitute contraindications to the administration of the investigational product on the day of planned vaccination.  The participant must be followed until resolution of the event as with any medical event and may be considered for vaccination at a later date (maximum 14 days later) or withdrawn at the discretion of the Investigator. Delays due to these events do not constitute a protocol deviation.  Temperature of >37.5°C at the time of vaccination Acute disease at the time of vaccination If there is a clinical/epidemiological suspicion of COVID-19 (according to the clinician's judgement), the participant will be asked to first take a PCR/rapid test for SARS-CoV2, and the vaccination will be delayed until the result comes back negative and the symptoms have resolved.