Immunogenicity and Safety of Different Vaccination Schedules of Tetravalent Dengue Vaccine in Healthy Subjects 9 to 50 Years of Age
Condition: Dengue Fever; Dengue Hemorrhagic Fever
MeSH terms: Dengue; Hemorrhagic Fevers, Viral; Severe Dengue; Fever; Hyperthermia
Study type: Interventional
Phase: Phase 2

Summary: 
      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: 
      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.
    

Intervention name(s): CYD Dengue Vaccine; Placebo (Sodium chloride 0.9%)
Intervention type(s): Biological; Biological
Intervention description(s): 0.5 mL, Subcutaneous; 0.5 mL, Subcutaneous
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: Dengue Fever; Dengue virus; Dengue Hemorrhagic Fever; CYD Dengue Vaccine