Immunogenicity and Safety of Different Vaccination Schedules of Tetravalent Dengue Vaccine in Healthy Subjects 9 to 50 Years of Age

Study Overview
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Brief Summary
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The aim of the study was to assess the immune response and the safety of different vaccination schedules of CYD dengue vaccine. The primary objectives of the study were: To demonstrate the non-inferiority of the immune response elicited against each dengue serotype by CYD dengue vaccine given as a 2-dose schedule (Group 2) compared to the immune response elicited by CYD dengue vaccine given as a 3-dose schedule (Group 1), in previously dengue exposed participants 28 days after the last injection. To demonstrate the non-inferiority of the immune response elicited against each dengue serotype by CYD dengue vaccine given as a 2-dose schedule (Group 2) compared to the immune response elicited by CYD vaccine given as a 3-dose schedule (Group 1) in previously dengue exposed participants, 1 year after the last injection. To demonstrate the non-inferiority of the immune response elicited against each dengue serotype elicited by a booster dose of CYD dengue vaccine one year or two years after the last injection in the primary series in previously dengue exposed participants, compared to the immune response post dose 3 in Group 1. The secondary objectives of the study were: To demonstrate the superiority of the immune response elicited by CYD dengue vaccine given as a 2-dose schedule (Group 2) compared to the immune response elicited by CYD dengue vaccine given as a 3-dose schedule (Group 1), in previously dengue exposed participants, 28 days after the last injection. To demonstrate the superiority of the immune response elicited by CYD dengue vaccine given as a 2-dose schedule (Group 2) compared to the immune response elicited by CYD dengue vaccine given as a 3-dose schedule (Group 1), in previously dengue exposed participants, one year after the last injection. To describe the neutralizing antibody levels of each dengue serotype at 28 days post-injection 3 to the antibody levels immediately before receiving a booster dose, by baseline dengue serostatus. To describe the neutralizing antibody levels of each dengue serotype at 28 days post-injection 2 and 28 days post-injection 3 from Group 1 in a primary series schedule by baseline dengue serostatus. To demonstrate the superiority of the immune response elicited against each dengue serotype 28 days after administration of a booster dose of CYD dengue vaccine, in previously dengue exposed participants, at one year or two years after last injection in the primary series. To describe the seroconversion rate 28 days post-booster injection in all 3 groups. To describe all hospitalized virologically confirmed dengue (VCD) cases during the study. To evaluate the safety profile of CYD after each and any injection during the trial. Safety assessments include solicited reactions within 7 or 14 days after each injection, unsolicited adverse events within 28 days after each injection, and serious adverse events during the study period.

Detailed Description
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Healthy participants aged between 9 and 50 year received CYD dengue vaccine in various schedules, in two sequential stages. In the first stage, participants received 1, 2 or 3 injections of CYD dengue vaccine over a 12-month period. In the second stage, participants were randomized to receive a booster dose of CYD dengue vaccine at either 12 months (Subgroup a) or 24 months (Subgroup b) after the third injection of study vaccine. During the conduction of this trial, the World Health Organization (WHO) indication about vaccinating only baseline seropositive participants was arisen; at this moment, STAGE I of the trial was completed. For STAGE II, only participants who were previously dengue exposed at baseline (dengue seropositive) were eligible to receive the booster dose.

Official Title
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Immunogenicity and Safety of Tetravalent Dengue Vaccine Given in 1-, 2-, or 3- Dose Schedules (STAGE I) Followed by a Single Booster Injection of the Same Vaccine (STAGE II) 1 or 2 Years After the Last Primary Dose in Healthy Subjects 9 to 50 Years of Age in Colombia and the Philippines

Conditions
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Dengue Fever, Dengue Hemorrhagic Fever

Intervention / Treatment
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* Biological: CYD Dengue Vaccine
* Biological: Placebo (Sodium chloride 0.9%)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Aged 9 to 50 years on the day of enrollment. Participant 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) were able to attend all scheduled visits and to comply with all trial procedures. Exclusion Criteria: Participant was pregnant, or lactating, or of childbearing potential (to be considered of non-childbearing potential, a female must be pre-menarche, surgically sterile, or using an effective method of contraception or abstinence from at least 4 weeks prior to the first vaccination until at least 4 weeks after the last vaccination). Participation at the time of study enrollment (or 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. Self-reported 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 systemic hypersensitivity to any of the vaccine components, or history of a life-threatening reaction to the vaccine 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. Planned receipt of any vaccine in the 4 weeks following any trial vaccination. Previous vaccination against dengue disease with either the trial vaccine or another vaccine. Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily. Current alcohol abuse or drug addiction that, based on investigator's judgment, might interfere with the participant's ability to comply with trial procedures. Identified as a site employee of the Investigator, 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 employees or the Investigator. A prospective participant must not be included in the study until the following conditions and/or symptoms were resolved: Febrile illness (temperature greater than or equal to [>=] 38.0 degree Celsius) or moderate or severe acute illness/infection (according to Investigator's judgment) on the day of vaccination. Receipt of any vaccine in the 4 weeks preceding the first trial vaccination.

Ages Eligible for Study
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Minimum Age: 9 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: STAGE-I Group 1: CYD Dengue Vaccine<br>Participants received 3 doses of CYD dengue vaccine 0.5 milliliters (mL) subcutaneously (SC) at Day 0 (Vaccination 1), Month 6 (Vaccination 2), and Month 12 (Vaccination 3). | Biological: CYD Dengue Vaccine<br>* 0.5 mL, Subcutaneous<br>|
| Experimental: STAGE-I Group 2: Placebo + CYD Dengue Vaccine (Months 6,12)<br>Participants received a dose of placebo at Day 0 (Vaccination 1) along with 2 doses of CYD dengue vaccine 0.5 mL SC at Month 6 (Vaccination 2) and Month 12 (Vaccination 3). | Biological: CYD Dengue Vaccine<br>* 0.5 mL, Subcutaneous<br>Biological: Placebo (Sodium chloride 0.9%)<br>* 0.5 mL, Subcutaneous<br>|
| Experimental: STAGE-I Group 3: Placebo + CYD Dengue Vaccine (Month 12)<br>Participants received 2 doses of placebo at Day 0 (Vaccination 1) and Month 6 (Vaccination 2) along with a dose of CYD dengue vaccine 0.5 mL SC at Month 12 (Vaccination 3). | Biological: CYD Dengue Vaccine<br>* 0.5 mL, Subcutaneous<br>Biological: Placebo (Sodium chloride 0.9%)<br>* 0.5 mL, Subcutaneous<br>|
| Experimental: STAGE-II Group 1a: CYD Vaccine + CYD Booster Vaccine (1 Year)<br>Participants from Group 1 who received vaccination in STAGE-I; and were seropositive at Baseline received a booster dose of CYD dengue vaccine in STAGE-II at 1 year post last dose in STAGE-I (i.e., at Month 24). | Biological: CYD Dengue Vaccine<br>* 0.5 mL, Subcutaneous<br>|
| Experimental: STAGE-II Group 2a: Placebo + CYD + CYD Booster (1 Year)<br>Participants from Group 2 who received vaccination in STAGE-I and were seropositive at baseline received a booster injection of CYD dengue vaccine in STAGE-II at 1 year post last dose in STAGE-I (i.e., at Month 24). | Biological: CYD Dengue Vaccine<br>* 0.5 mL, Subcutaneous<br>Biological: Placebo (Sodium chloride 0.9%)<br>* 0.5 mL, Subcutaneous<br>|
| Experimental: STAGE-II Group 3a: Placebo + CYD + CYD Booster (1 Year)<br>Participants from Group 3 who received vaccination in STAGE-I and were seropositive at Baseline received a booster injection of CYD dengue vaccine in STAGE-II at 1 year post last dose in STAGE-I (i.e., at Month 24). | Biological: CYD Dengue Vaccine<br>* 0.5 mL, Subcutaneous<br>Biological: Placebo (Sodium chloride 0.9%)<br>* 0.5 mL, Subcutaneous<br>|
| Experimental: STAGE-II Group 1b: CYD Vaccine + CYD Booster Vaccine (2 Years)<br>Participants from Group 1 who received vaccination in STAGE-I and were seropositive at Baseline received a booster injection of CYD dengue vaccine in STAGE-II at 2 years post last dose in STAGE-I (i.e., at Month 36). | Biological: CYD Dengue Vaccine<br>* 0.5 mL, Subcutaneous<br>|
| Experimental: STAGE-II Group 2b: Placebo + CYD + CYD Booster (2 Years)<br>Participants from Group 2 who received vaccination in STAGE-I and were seropositive at Baseline received a booster injection of CYD dengue vaccine in STAGE-II at 2 years post last dose in STAGE-I (i.e., at Month 36). | Biological: CYD Dengue Vaccine<br>* 0.5 mL, Subcutaneous<br>Biological: Placebo (Sodium chloride 0.9%)<br>* 0.5 mL, Subcutaneous<br>|
| Experimental: STAGE-II Group 3b: Placebo + CYD + CYD Booster (2 Years)<br>Participants from Group 3 who received vaccination in STAGE-I and were seropositive at baseline received a booster injection of CYD dengue vaccine in STAGE-II at 2 years post last dose in STAGE-I (i.e., at Month 36). | Biological: CYD Dengue Vaccine<br>* 0.5 mL, Subcutaneous<br>Biological: Placebo (Sodium chloride 0.9%)<br>* 0.5 mL, Subcutaneous<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| STAGE-I: Geometric Mean Titers (GMTs) Against Each Dengue Virus Serotype 28 Days After Last CYD Dengue Vaccination in Participants Who Were Seropositive at Baseline | GMTs of antibodies against each of the 4 dengue virus serotypes (1, 2, 3, or 4) were assessed using plaque reduction neutralization test (PRNT) assay method. Titers were measured in terms of 1/dilution. Dengue seropositive participants at Baseline was defined as participants with titers >=10 (1/dilution) for at least 1 serotype with parental dengue virus strains. Per-protocol analysis set (PPAS) included all participants who had no protocol violations; and who met any of following study violations were excluded from PPAS (STAGE I/II): had not met all protocol-specified inclusion/exclusion criteria, had not received correct doses or injections, received vaccine other than randomized schedule, did not receive vaccination in proper time window, had not provided post-dose serology sample in proper time window, received protocol-restricted medication, therapy, or vaccine. | 28 days after last CYD dengue vaccination | 
| STAGE-I: Geometric Mean Titers Against Each Dengue Virus Serotype 1 Year After Last CYD Dengue Vaccination in Participants Who Were Seropositive at Baseline | GMTs of antibodies against each of the 4 dengue virus serotypes (1, 2, 3 or 4) were assessed using the PRNT assay method. Titers were measured in terms of 1/dilution. Dengue seropositive participants at Baseline were defined as participants with titers >=10 (1/dilution) for at least one serotype with the parental dengue virus strains. | 1 year after last CYD dengue vaccination | 
| STAGE-II: Geometric Mean Titers Against Each Dengue Virus Serotype Within Group 1a and Group 1 After the Third Dose of CYD Dengue Vaccination in Participants Who Were Seropositive at Baseline | GMTs of antibodies against each of the 4 dengue virus serotypes (1, 2, 3 or 4) were assessed using the PRNT assay method. Titers were measured in terms of 1/dilution. Dengue seropositive participants at Baseline were defined as participants with titers >=10 (1/dilution) for at least one serotype with the parental dengue virus strains. Data of Group 1 (28 days post-dose 3 in STAGE-I) and Group 1a (28 days 12 months Booster dose) were reported and compared in this outcome measure. GMT paired ratio (given in statistical analysis section) was calculated by dividing geometric mean values of Group 1a: 28 days post 12 months booster dose in STAGE-II by Group 1: 28 days post-dose 3 in STAGE-I. | Group 1: 28 days post-dose 3 in STAGE-I, Group 1a: 28 days post 12 months booster dose in STAGE-II | 
| STAGE-II: Geometric Mean Titers Against Each Dengue Virus Serotype Comparison Between Group 2a and Group 1 After the Third Dose of CYD Dengue Vaccination in Participants Who Were Seropositive at Baseline | GMTs of antibodies against each of the 4 dengue virus serotypes (1, 2, 3 or 4) were assessed using the PRNT assay method. Titers were measured in terms of 1/dilution. Dengue seropositive participants at Baseline were defined as participants with titers >=10 (1/dilution) for at least one serotype with the parental dengue virus strains. Data of Group 1 (28 days post-dose 3 in STAGE-I) and Group 2a (28 days post 12 months Booster dose) were reported and compared in this outcome measure. GMT ratio (given in statistical analysis section) was calculated by dividing geometric mean values of Group 2a: 28 days post 12 months booster dose in STAGE-II by Group 1: 28 days Post-dose 3 in STAGE-I. | Group 1: 28 days post-dose 3 in STAGE-I, Group 2a: 28 days post 12 months booster dose in STAGE-II | 
| STAGE-II: Geometric Mean Titers Against Each Dengue Virus Serotype Within Group 1b and Group 1 After the Third Dose of CYD Dengue Vaccination in Participants Who Were Seropositive at Baseline | GMTs of antibodies against each of the 4 dengue virus serotypes (1, 2, 3 or 4) were assessed using the PRNT assay method. Titers were measured in terms of 1/dilution. Dengue seropositive participants at Baseline were defined as participants with titers >=10 (1/dilution) for at least one serotype with the parental dengue virus strains. Data of Group 1 (28 days post-dose 3 in STAGE-I) and Group 1b (28 days post 24 months booster dose) were reported and compared in this outcome measure. GMT paired ratio (given in statistical analysis section) was calculated by dividing geometric mean values of Group 1b: 28 days post 24 months booster dose in STAGE-II by Group 1: 28 days Post-dose 3 in STAGE-I. | Group 1: 28 days post-dose 3 in STAGE-I, Group 1b: 28 days post 24 months booster dose in STAGE-II | 
| STAGE-II: Geometric Mean Titers Against Each Dengue Virus Serotype Comparison Between Group 2b and Group 1 After the Third Dose of CYD Dengue Vaccination in Participants Who Were Seropositive at Baseline | GMTs of antibodies against each of the 4 dengue virus serotypes (1, 2, 3 or 4) were assessed using the PRNT assay method. Titers were measured in terms of 1/dilution. Dengue seropositive participants at Baseline were defined as participants with titers >=10 (1/dilution) for at least one serotype with the parental dengue virus strains. Data of Group 1 (28 days post-dose 3 in STAGE-I) and Group 2b (28 days post 24 months Booster dose) was reported and compared in this outcome measure. GMT ratio (given in statistical analysis section) was calculated by dividing geometric mean values of Group 2b: 28 days post 24 months booster dose in STAGE-II by Group 1: 28 days post-dose 3 in STAGE-I. | Group 1: 28 days post-dose 3 in STAGE-I, Group 2b: 28 days post 24 months Booster dose in STAGE-II | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| STAGE-I: Geometric Mean Titers Against Each Serotype With the Parental Dengue Virus Strains After CYD Dengue Vaccination in Participants Who Were Seropositive at Baseline-Comparison Between Group 1 and Group 2 | GMTs of antibodies against each of the 4 dengue virus serotypes (1, 2, 3 or 4) were assessed using the PRNT assay method. Titers were measured in terms of 1/dilution. Dengue seropositive participants at Baseline were defined as participants with titers >=10 (1/dilution) for at least one serotype with the parental dengue virus strains. | 28 days and 1 year after last CYD dengue vaccination | 
| STAGE-I: Geometric Mean Titers Against Each Serotype With the Parental Dengue Virus Strains in All Participants | GMTs of antibodies against each of the 4 dengue virus serotypes (parental strains) were assessed using the PRNT assay method. | Baseline, 28 days post vaccination 3, and 1 year post vaccination 3 | 
| STAGE-I: Geometric Mean Titers Against Each Serotype With the Parental Dengue Virus Strains (by Baseline Dengue Status) in Participants Who Were Seropositive and Seronegative at Baseline | GMTs of antibodies against each of the 4 dengue virus serotypes (1, 2, 3, or 4) were assessed using the PRNT assay method. Titers were measured in terms of 1/dilution. Dengue seropositive participants at Baseline were defined as participants with titers >=10 (1/dilution) for at least one serotype with the parental dengue virus strains. Dengue seronegative participants at Baseline were defined as the participants with valid titer <0 (1/dilution) for all serotypes with parental dengue virus strains. | Baseline, 28 days post vaccination 3, and 1 year post vaccination 3 | 
| STAGE-II: Geometric Mean Titers Against Each Serotype With the Parental Dengue Virus Strains After Booster CYD Dengue Vaccination in Participants Seropositive at Baseline | GMTs of antibodies against each of the 4 dengue virus serotype (1, 2, 3, or 4) were assessed using the PRNT assay. Dengue seropositive participants at Baseline were defined as participants with titers >=10 (1/dilution) for at least one serotype with the parental dengue virus strains. Titers were measured in terms of 1/dilution. | Baseline, 28 days post vaccination-3, and 28 days post booster dose | 
| STAGE-I: Percentage of Participants With Antibodies Titer >=10 (1/Dilution) Against Each Serotype With the Parental Dengue Virus Strains in All Participants | GMTs of antibodies against each of the 4 dengue virus serotypes (1, 2, 3 or 4) were assessed using the PRNT assay. | Baseline, 28 days post vaccination 3, and 1 year post vaccination 3 | 
| STAGE-II: Percentage of Participants With Antibodies Titer >=10 (1/Dilution) Against Each Serotype With the Parental Dengue Virus Strain in Participants Seropositive at Baseline | GMTs of antibodies against each of the 4 dengue virus serotypes (1, 2, 3 or 4) were assessed using the PRNT assay method. Dengue seropositive participants at Baseline were defined as participants with titers >=10 (1/dilution) for at least one serotype with the parental dengue virus strains. | Baseline, 28 days post vaccination 3, and 1 year post vaccination 3 | 
| STAGE-I: Number of Participants With Immediate Unsolicited Adverse Events Following Vaccination With CYD Dengue Vaccine or Placebo (Post Any Vaccination) | An AE was defined as any unfavorable and unintended sign (including an abnormal laboratory finding, for example), symptom or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. An unsolicited AE was an observed AE that did not fulfill the conditions prelisted in the electronic case report form (eCRF) in terms of diagnosis and/or onset post-vaccination. Immediate unsolicited AE were AEs that occurred within 30 minutes after any vaccination. | Within 30 minutes after any vaccination (1, 2, or 3) | 
| STAGE-II: Number of Participants With Immediate Unsolicited Adverse Events Following Booster Vaccination With CYD Dengue Vaccine | An AE was defined as any unfavorable and unintended sign (including an abnormal laboratory finding, for example), symptom or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. An unsolicited AE was an observed AE that did not fulfill the conditions prelisted in the eCRF in terms of diagnosis and / or onset post-vaccination. Immediate unsolicited AE were AEs that occurred within 30 minutes after vaccination. | Within 30 minutes after CYD booster vaccination | 
| STAGE-I: Number of Participants With Solicited Injection Site Reactions Following Vaccination With CYD Dengue Vaccine or Placebo (Post Any Vaccination) | Adverse reaction (AR) was defined as all noxious and unintended responses to a medicinal product related to any dose. A Solicited Reaction (SR) was defined as an AR observed and reported under the conditions (symptom and onset) prelisted (i.e., solicited) in the eCRF and considered as related to vaccination. Solicited injection site reaction was an AR at and around the injection site that included pain, erythema, and swelling. | Within 7 days after any vaccination (1, 2, or 3) | 
| STAGE-I: Number of Participants With Solicited Injection Site Reactions Following Vaccination With CYD Dengue Vaccine or Placebo (Post Each Vaccination) | AR was defined as all noxious and unintended responses to a medicinal product related to any dose. An SR was defined as an AR observed and reported under the conditions (symptom and onset) prelisted (i.e., solicited) in the eCRF and considered as related to vaccination. Solicited injection site reaction was an AR at and around the injection site that included pain, erythema, and swelling. | Within 7 days after each vaccination (1, 2, and 3) | 
| STAGE-I: Number of Participants With Solicited Systemic Reactions Following Vaccination With CYD Dengue Vaccine or Placebo (Post Any Vaccination) | An AR was defined as all noxious and unintended responses to a medicinal product related to any dose. An SR was defined as an AR observed and reported under the conditions (symptom and onset) prelisted (i.e., solicited) in the eCRF and considered as related to vaccination. Systemic AEs were all AEs that were not injection site reactions. Solicited systemic reactions included fever, headache, malaise, myalgia, and asthenia. | Within 14 days after any vaccination (1, 2, or 3) | 
| STAGE-I: Number of Participants With Solicited Systemic Reactions Following Vaccination With CYD Dengue Vaccine or Placebo (Post Each Vaccination) | An AR was defined as all noxious and unintended responses to a medicinal product related to any dose. A SR was defined as an AR observed and reported under the conditions (symptom and onset) prelisted (i.e., solicited) in the eCRF and considered as related to vaccination. Solicited systemic reactions included fever, headache, malaise, myalgia, and asthenia. | Within 14 days after each vaccination (1, 2, and 3) | 
| STAGE-II: Number of Participants With Solicited Injection Site Reactions Following Booster Vaccination With CYD Dengue Vaccine | An AR was defined as all noxious and unintended responses to a medicinal product related to any dose. A SR was defined as an AR observed and reported under the conditions (symptom and onset) prelisted (i.e., solicited) in the eCRF and considered as related to vaccination. Solicited injection site reaction was an AR at and around the injection site that included pain, erythema, and swelling. | Within 7 days after CYD booster vaccination | 
| STAGE-II: Number of Participants With Solicited Systemic Reactions Following Booster Vaccination With CYD Dengue Vaccine | An AR was defined as all noxious and unintended responses to a medicinal product related to any dose. A SR was defined as an AR observed and reported under the conditions (symptom and onset) prelisted (i.e., solicited) in the eCRF and considered as related to vaccination. Solicited systemic reactions included fever, headache, malaise, myalgia, and asthenia. | Within 14 days after CYD booster vaccination | 
| STAGE-I: Number of Participants Reporting Unsolicited Adverse Events Following Vaccination With CYD Dengue Vaccine or Placebo | An AE was defined as any unfavorable and unintended sign (including an abnormal laboratory finding, for example), symptom or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. An unsolicited AE was an observed AE that did not fulfill the conditions prelisted in the eCRF in terms of diagnosis and/or onset post-vaccination. | Within 28 days after any vaccination (1, 2, or 3) | 
| STAGE-II: Number of Participants Reporting Unsolicited Adverse Events Following Booster Vaccination With CYD Dengue Vaccine | An AE was defined as any unfavorable and unintended sign (including an abnormal laboratory finding, for example), symptom or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. An unsolicited AE was an observed AE that does not fulfill the conditions prelisted in the eCRF in terms of diagnosis and/or onset post-vaccination. | Within 28 days after CYD booster Vaccination | 
| STAGE-I: Number of Participants Reporting Serious Adverse Events Including Serious Adverse Event of Special Interests (AESI) Following Vaccination With CYD Dengue Vaccine or Placebo | An AE was defined as any unfavorable and unintended sign (including an abnormal laboratory finding, for example), symptom or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. An SAE was any untoward medical occurrence that at any dose resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was congenital anomaly/birth defect, or was an important medical event. AESI were AEs that were considered by the Sponsor to be relevant for the monitoring of the safety profile of the investigational vaccine. | From Day 0 (post vaccination) up to 12 months after last vaccination in STAGE-I (i.e., up to 24 months) | 
| STAGE-II: Number of Participants Reporting Serious Adverse Events Including Serious Adverse Events Special Interest Following Booster Vaccination With CYD Dengue Vaccine | An AE was defined as any unfavorable and unintended sign (including an abnormal laboratory finding, for example), symptom or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. An SAE was any untoward medical occurrence that at any dose resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was congenital anomaly/birth defect, or was an important medical event. AESI were AEs that were considered by the Sponsor to be relevant for the monitoring of the safety profile of the investigational vaccine. | From Month 25 up to 6 months after CYD booster injection (either at 1 year or 2 year) (i.e., up to 30 months for Groups 1a, 2a, and 3a and up to 42 months for Groups 1b, 2b, and 3b) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Dengue Fever, Dengue virus, Dengue Hemorrhagic Fever, CYD Dengue Vaccine