Immunologic Mechanisms of Immune Interference and/or Cross-Neutralizing Immunity After CYD Tetravalent Dengue Vaccine

Study participants will be randomly assigned to one of the four groups to receive assigned
study vaccine and will be evaluated neutralizing antibody (Ab) titers; markers of
cell-mediated immunity (CMI)

Inclusion Criteria:

- Aged ≥ 18 to ≤ 45 years on the day of inclusion

- Informed consent form has been signed and dated

- Able to attend all scheduled visits and to comply with all trial procedures

- Subject in good health, based on medical history and physical examination.

Exclusion Criteria:

- Subject is 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 or planned receipt of any vaccine, outside the study protocol in the 4 weeks
preceding or following trial vaccinations. (If influenza activity warrants
vaccination of healthy young adults, influenza vaccination will be encouraged and
will not lead to study exclusion.)

- Any history of flavivirus (FV) vaccination, or planned FV vaccination during the
trial period.

- Previous residence (>12 months) in, or travel in the last 30 days to dengue endemic
regions.

- Receipt of immune globulins, blood or blood-derived products in the 3 months prior to
first vaccination or planned use during the study period

- 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)

- Known systemic hypersensitivity to any of the vaccine components (including protamine
sulfate), 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

- Excessive alcohol consumption 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

- Temporary Exclusion Criteria: 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 subject should not be included in the study until
the condition has resolved or the febrile event has subsided. If the delay for the
febrile illness exceeds the window between screening and vaccination, or if deemed
necessary by the Investigator, a prospective subject may be re-screened once the
fever has resolved.