Immune Response to Different Schedules of a Tetravalent Dengue Vaccine Given With or Without Yellow Fever Vaccine

Participants were randomized to 4 different groups to receive either CYD dengue vaccine and/or YF vaccine. Participants who already received YF vaccine prior to enrolment were randomized to one of the 2 groups receiving CYD dengue vaccine alone. Participants were evaluated for immunogenicity, antibody persistence, reactogenicity and safety.

Inclusion criteria

• Aged >= 18 to <= 45 years on the day of inclusion
• Informed consent form had been signed and dated
• Able to attend all scheduled visits and complied with all trial procedures
• For participants classified as YF positive (+) to be included in Groups 1 and 2, previous vaccination (3 months to 10 years) with YF vaccine confirmed by acceptable documentation.

Exclusion criteria

• Participant was pregnant, or lactating, or of childbearing potential (to be considered of non-childbearing potential, a female must be post-menopausal for at least 1 year, surgically sterile, or using an effective method of contraception or abstinence from at least 4 weeks prior to the first vaccination and until at least 4 weeks after the last vaccination)
• 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 or planned receipt of any vaccine in the 4 weeks following each trial vaccination
• For all participants classified as YF negative (-), any previous vaccination against Flavivirus (FV) diseases (including Japanese Encephalitis [JE], tick-borne encephalitis, and YF)
• For participants classified as YF+, previous vaccination against FV diseases except YF (including JE and tick-borne encephalitis)
• For all participants, any FV vaccination planned during the trial period outside the study protocol
• Receipt of immune globulins, blood or blood-derived products in the past 3 months
• Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months)
• Self-reported seropositivity for human immunodeficiency virus (HIV), hepatitis B, or hepatitis C
• Self-reported history of FV infection (e.g., JE, Dengue, YF, West Nile), confirmed either clinically or serologically
• Known systemic hypersensitivity to any of the vaccine components, or history of a life-threatening reaction to the vaccine(s) used in the trial or to a vaccine containing any of the same substances, including dry natural latex
• Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily
• Current alcohol abuse or drug addiction
• Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion
• Identified as an employee of the Investigator or study center, with direct involvement in the proposed study or other studies under the direction of that Investigator or study center, as well as family members (i.e., immediate, husband, wife and their children, adopted or natural) of the employee or the Investigator
• Moderate or severe acute illness/infection (according to investigator judgment) on the day of vaccination or febrile illness (temperature >= 38.0°C [>=100.4°F]). A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided
• Previous residence (> 12 months) in, or travel in the last 30 days to FV endemic regions
• History of thymic pathology (thymoma), thymectomy, or myasthenia.