Study of a Booster Dose of a Tetravalent Dengue Vaccine in Subjects Who Previously Completed the 3-dose Schedule

The aim of the study was to assess and describe the booster effect of a CYD dengue vaccine dose administered 4 to 5 years after the completion of a 3-dose vaccination schedule.

Primary Objective

- To demonstrate the non-inferiority, in terms of geometric mean of titer ratios (GMTRs), of a CYD dengue vaccine booster compared to the third CYD dengue vaccine injection in participants from CYD13 - NCT00993447 and CYD30 - NCT01187433 trials (participants from Group 1 only).

Secondary Objectives:

* If the primary objective of non-inferiority was achieved: To demonstrate the superiority, in terms of GMTRs, of a CYD dengue vaccine booster compared to the third CYD dengue vaccine injection in participants from CYD13 and CYD30 trials.
* To describe the immune responses elicited by a CYD dengue vaccine booster and placebo injection in participants who received 3 doses of the CYD dengue vaccine in the CYD13 and CYD30 trials in all participants.
* To describe the neutralizing antibody levels of each dengue serotype post-dose 3 (CYD13 and CYD30 participants) and immediately prior to booster or placebo injection in all participants.
* To describe the neutralizing antibody persistence 6 months, 1 year, and 2 years post booster or placebo injection in all participants.
* To evaluate the safety of booster vaccination with the CYD dengue vaccine in all participants.

Healthy adolescents and adults who received 3 doses of the tetravalent dengue vaccine 4 to 5 years earlier in previous CYD dengue vaccine trials (CYD13 and CYD30) received either a booster dose CYD dengue vaccine or a placebo on Day 0. They were evaluated for safety and antibody persistence of the booster injection up to 2 years post-vaccination.

Eligibility Criteria:
Inclusion Criteria:

* Had been identified as a potential participant by the Sponsor and is included in the list provided to the Investigator (i.e., aged 9 to 16 years on the day of first vaccination of CYD dengue vaccine in CYD13/CYD30 and has a post-dose 3 serum sample available \[at least 400 microliters of serum\]).
* Participants were in good health, based on medical history and physical examination.
* Assent form or informed consent form (ICF) had been signed and dated by the participant (based on local regulations), and ICF had been signed and dated by the parent(s) or another legally acceptable representative (and by an independent witness if required by local regulations).
* Participant and parent(s)/legally acceptable representative(s) attended all scheduled visits and complied with all trial procedures.

Exclusion Criteria:

* Participant who received any other dengue vaccination that was not part of the CYD13 or CYD30 trials.
* Participant was pregnant, or lactating, or of childbearing potential (to be considered of non childbearing potential, a female must be pre-menarche or 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 vaccination until at least 4 weeks after vaccination).
* Participation at the time of study enrollment (or in the 4 weeks preceding the 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 trial vaccination or planned receipt of any vaccine in the 4 weeks following the trial vaccination.
* 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).
* Known systemic hypersensitivity to any of the vaccine components, or history of a life-threatening reaction to the vaccines used in the trial or to a vaccine containing any of the same substances.
* Chronic illness that, in the opinion of the Investigator, was at a stage where it might interfere with trial conduct or completion.
* Receipt of blood or blood-derived products in the past 3 months, which might interfere with assessment of the immune response.
* Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily.
* Current alcohol abuse or drug addiction.
* Moderate or severe acute illness/infection (according to investigator judgment) on the day of vaccination or febrile illness (temperature \>= 38.0°C). A prospective participant should not be included in the study until the condition had resolved or the febrile event had subsided.
* Identified as an Investigator or employee of the Investigator or study center 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.