The vaccine being tested in this study is Takeda's Tetravalent Dengue Vaccine Candidate (TDV). This study is designed to determine whether the lyophilized formulation provides equivalent safety and immunogenicity as the original liquid formulation. An exploratory analysis has been added for the purpose of understanding whether there is a manufacturing or formulation effect on the vaccine.~The study will enroll approximately 1000 participants. Participants will be randomly assigned (by chance, like flipping a coin) to one of the four study groups-which will remain undisclosed to the participant and study doctor during the study (unless there is an urgent medical need):~Group A: TDV Liquid Formulation 1, subcutaneous (SC) injection on Day 1 and placebo (dummy) SC at Month 3 - this is a liquid that looks like the study drug but has no active ingredient~Group B: TDV Liquid Formulation 1, SC injection Day 1 and Month 3~Group C: TDV Liquid Formulation 2, SC injection Day 1 and Month 3~Group D: TDV Lyophilized formulation SC injection Day 1 and Month 3~In order to keep the treatment arms undisclosed to the participant and the doctor, participants will receive a placebo injection at any study visit where TDV is not being administered (Month 3). Participants will be asked to record any adverse events that may be related to the vaccine or the injection in a diary card for 28 days after each vaccination.~This multi-center trial will be conducted in the United States. The overall time to participate in this study is up to 10 months. Participants will make 9 visits to the clinic including a final visit 1 month after last dose of study drug for a follow-up assessment. A follow up phone call will be done 6 months after the last dose to assess serious adverse events.
The purpose of this study is to evaluate the equivalence of the lyophilized formulation of Takeda's Tetravalent Dengue Vaccine Candidate (TDV) compared with the liquid formulation of TDV.