Immunogenicity and Safety of Tetravalent Dengue Vaccine (TDV) Administered With a Yellow Fever Vaccine in Adults

The main purpose of this study is to assess the immunogenicity and safety of the concomitant and sequential administration of yellow fever (YF) vaccine and tetravalent dengue vaccine (TDV) in healthy participants aged 18 to 60 years living in country non-endemic for both dengue and YF.

The vaccine tested in this study is TDV also known as TAK-003 (DENVax). TDV with concomitant and sequential administration of yellow fever (YF-17D) vaccine will be tested to assess immunogenicity and safety in healthy adult participants in non-endemic area(s) for both dengue and YF.

The study will enroll 900 healthy participants. Participants will be randomized to 3 groups in 1:1:1 ratio and will be administered concomitantly and sequentially. The 3 groups are:

* Group 1: YF-17D vaccine + placebo concomitantly administered on Day 1, first dose of TDV administered on Day 90 and second dose of TDV administered on Day 180.
* Group 2: first dose of TDV + placebo concomitantly administered on Day 1, second dose of TDV administered on Day 90 and YF-17D vaccine administered on Day 180.
* Group 3: first dose of TDV + YF-17D vaccine concomitantly administered on Day 1, second dose of TDV administered on Day 90 and placebo administered on Day 180.

This multi-center trial will be conducted in the United States. The overall time to participate in this study is 360 days. Participants will make multiple visits to the clinic with a 6-month follow up including a final visit at Day 360 for a follow-up assessment.

Eligibility Criteria:
Inclusion Criteria:

1. Is aged 18 to 60 years inclusive, at the time of randomization.
2. Is in good health at the time of entry into the trial as determined by medical history, physical examination (including vital signs), and the clinical judgment of the Investigator.

Exclusion Criteria:

1. Has an elevated oral temperature ≥ 38°C (100.4°F) within 3 days of the intended date of vaccination.
2. Has contraindications, warnings and/or precautions to vaccination with the YF-17D vaccine as specified within the product information (especially history of thymus dysfunction).
3. Female participant who are pregnant or breastfeeding
4. Has any history of progressive or severe neurologic disorder, seizure disorder or neuro-inflammatory disease (e.g., Guillain-Barre syndrome) or suspected impairment/alteration of immune function.
5. Has body mass index (BMI) greater than or equal to 35 kg/m\^2 (=weight in kg/\[height in meters\^2\]).
6. Is intent to travel to dengue or YF endemic countries during the trial period.
7. Has received any other vaccines within 14 days (for inactivated vaccines) or 28 days (for live vaccines) prior to enrollment in this trial or who are planning to receive any non-trial vaccine within 28 days of trial vaccine administration.
8. Has previous and planned vaccination (during the trial conduct), against any flavivirus including dengue, YF, Japanese encephalitis (JE) or tick-borne encephalitis viruses.
9. Has previous participation in any clinical trial of a dengue or other flavivirus (e.g., West Nile \[WN\] virus) candidate vaccine, except for participants who received placebo in those trials.
10. Has a current or previous infection with a flavivirus such as dengue, Zika, YF, JE, WN fever, or Saint Louis encephalitis viruses and participants with a history of prolonged (≥1 year) habitation in a dengue endemic area.