Inclusion Criteria:

• Healthy, as determined by medical history, clinical examination, and biological safety parameters.
• Aged 18 to 45 years on the day of inclusion.
• Provision of informed consent signed by the subject or another legally acceptable representative.
• For a woman of child-bearing potential, use of an effective method of contraception or abstinence for at least 4 weeks prior to the first vaccination, and until at least 4 weeks after the last study vaccination.
• Able to attend all scheduled visits and to comply with all trial procedures.

Exclusion Criteria:

• Personal or family history of thymic pathology (thymoma), thymectomy, or myasthenia.
• For a woman of child-bearing potential, known or suspected pregnancy or positive serum/urine pregnancy test.
• Breast-feeding woman.
• Participation in another clinical trial investigating a vaccine, drug, medical device, or a medical procedure in the 4 weeks preceding the first trial vaccination.
• Planned participation in another clinical trial during the present trial period.
• Known or suspected congenital or acquired immunodeficiency, immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months, or long-term (at least 2 weeks within the previous 3 months) systemic corticosteroids therapy (at a dose of at least 10 mg).

Topical steroids are allowed.

• Known systemic hypersensitivity to any of the vaccine components or history of a life-threatening reaction to the trial vaccine or to a vaccine containing any of the same substances.
• Chronic illness at a stage that could interfere with trial conduct or completion, in the opinion of the investigator.
• Current or past alcohol abuse or drug addiction that may interfere with the subject's ability to comply with trial procedures.
• Receipt of blood or blood-derived products in the past 3 months, that might interfere with the assessment of immune response.
• Receipt of any vaccine in the 4 weeks preceding the first trial vaccination.
• Planned receipt of any vaccine in the 4 weeks following each of the trial vaccinations.
• Human Immunodeficiency Virus (HIV), hepatitis B surface antigen, or hepatitis C seropositivity in blood sample taken at Screening.
• Subject deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized without his/her consent.
• Clinically significant laboratory test abnormalities (as determined by the investigator) in blood sample taken at Screening.
• Previous residence in, travel or planned travel of more than 2 weeks during the study period to areas with high dengue infection endemicity. (Please refer to Appendix 5 of the protocol.)
• Reported history of flavivirus infection as reported by the subject.
• Previous vaccination against flavivirus diseases (including Japanese encephalitis, tick-borne encephalitis, and yellow fever)
• Flavivirus vaccination planned during the trial period.