Dengue fever is caused by an infection with the dengue virus. Vaccination with Dengue Tetravalent Vaccine (TDV) can help prevent dengue fever. The TDV in current formulation has been approved by health authorities in many countries around the world. The main aim of the study is to confirm that the TDV new formulation induces the similar immune response as approved TDV.

Healthy adults who live in an area in which dengue fever does not occur will receive 2 TDV vaccinations 3-months apart with either the new or the current TDV. Blood samples will be taken before and after the vaccinations. These are necessary to check how well the vaccine works to activate the immune system. During the study, participants will visit their study clinic 5 times.

Inclusion Criteria

• Participant eligibility is determined according to the following criteria:
• Participant is aged 18 to 60 years at the time of entry into the trial.
• Participant is male or female.
• Participant is in good health at the time of entry into the trial, as determined by medical history, physical examination, and the clinical judgment of the investigator.
• Participant is immunologically naive to dengue, based on negative results for the detection of anti-DENV antibodies as documented by serological testing at screening.
• Participant has signed and dated a written informed consent form (ICF) and any required privacy authorization prior to the initiation of any trial procedures, and after the nature of the trial has been explained according to local regulatory requirements.
• Participant can comply with trial procedures and is available for the duration of follow-up.

Exclusion Criteria

• Participant has contraindication(s), warning(s), and/or precaution(s) applicable to vaccination with TDV as specified in the IB and/or approved product label in the participating country.

• Participant has a known hypersensitivity or allergy to any of the Dengue Tetravalent Vaccine (Live, Attenuated) (TDV) components (including excipients).

• Participant has behavioral or cognitive impairment or psychiatric disease that, in the opinion of the investigator, could interfere with the participant's ability to take part in the trial.

• Participant has a history of progressive or severe neurologic disorder, seizure disorder, or neuro-inflammatory disease (eg, Guillain-Barré syndrome).

• Participant has an illness or history of any illness that, in the opinion of the investigator, might interfere with the results of the trial or pose additional risk to the participant due to involvement in this trial.

• Participant has a known or suspected altered immunocompetence, including:

  1. Chronic administration of oral and/or parenteral steroids at doses considered sufficiently immunosuppressive (example, greater than and equal to [>=] 2 milligrams per kilograms [mg/kg] body weight/day prednisone [or equivalent] for >=14 consecutive days or >=20 mg/day prednisone [or equivalent] administered for >=14 consecutive days) within 60 days prior to Day 1 (Month [M] 0) (note: use of corticosteroids by inhaled, intranasal, intra-articular, bursal, tendon injection, or topical routes is allowed).

  2. Receipt of immunoglobulins and/or any blood products within the 3 months prior to Day 1 (M0) or planned administration during the trial.

  3. Receipt of immunostimulants within 60 days prior to Day 1 (M0).

  4. Immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy within 6 months prior to Day 1 (M0).

  5. Human immunodeficiency virus (HIV) infection or HIV-related disease.

  6. Hepatitis B virus infection.

  7. Hepatitis C virus infection.

  8. Genetic immunodeficiency. 7. Participant has known or suspected abnormalities of splenic or thymic function.

     8. Participant has a known bleeding diathesis or any condition/medication that may be associated with a prolonged bleeding time.

• Participant has a serious chronic or progressive disease deemed to be preclusive to trial entry, that is, not medically stable according to the judgment of the investigator.

• Participant has a known previous infection with any flavivirus, including dengue, yellow fever, Japanese encephalitis, or tick-borne encephalitis viruses.

• Participant has previous or planned (during the trial conduct) vaccination against any flavivirus, including dengue (investigational or licensed vaccine), yellow fever viruses, Japanese encephalitis, or tick-borne encephalitis.

• Participant has a clinically significant active infection (as assessed by the investigator) or body temperature >= 38.0 degrees Celsius (°C) (>=100.4 degrees Fahrenhit [°F]) within 3 days of intended TDV administration.

• Participant has used antipyretics and/or analgesic medications within 24 hours prior to vaccination. The reason for their use (prophylaxis vs treatment) must be documented. Trial entry must be delayed to allow for a full 24 hours to have passed since last use of antipyretics and/or analgesic medications.

• Participant has a history of substance or alcohol abuse within the past 2 years.

• Female participants who are pregnant (ie, a positive or indeterminate pregnancy test).

• Female participants who are breastfeeding.

• Female participants of childbearing potential1 who are sexually active and who have not used any of the acceptable contraceptive methods2 for at least 2 months prior to Day 1 (M0).

• Female participants of childbearing potential1 who are sexually active with a non-sterilized male partner and refuse to use an acceptable contraceptive method up to 6 weeks post second TDV vaccination on Day 90 (M3), or who are planning to donate ova up to 6 weeks each post first (on Day 1 [M0]) and post second (on Day 90 [M3]) TDV administration.

• Non-sterilized male participants who are sexually active with a female partner of childbearing potential1 and refuse to use a barrier method 4 of contraception up to 6 weeks each post first (on Day 1 [M0]) and post second (on Day 90 [M3]) TDV administration, or who are planning to donate sperm during these periods.

• Participant has received any of the following:

  1. A licensed vaccine within 14 days (for inactivated or mRNA vaccines) or 28 days (for live or vector-based [if vector amplifies in body] vaccines) prior to TDV administration.
  2. A vaccine authorized for emergency use within 28 days prior to TDV administration.

• Participant is scheduled to receive any vaccine within 28 days after TDV administration.

• Participant is participating in any clinical trial with another investigational product 30 days prior to Day 1 (M0) or intending to participate in another clinical trial at any time during the conduct of this trial.

• Participant has taken part in any clinical trial of a dengue or other flavivirus (example, West Nile virus, Japanese encephalitis) candidate vaccine, except if it is known that the participant received placebo in those trials.

• Participant is planning to donate blood, organs, or tissues up to 6 weeks post second vaccination on Day 90 (M3).

• Participant or their first-degree relatives are involved in the trial conduct.

• Participant identified as an employee of the investigator or trial center, with direct involvement in the proposed trial or other trials under the direction of that investigator or trial center.

• Participant has lived in a dengue-endemic area for >=3 months.

• Participant has planned travel (during trial conduct) to any endemic area for dengue and other flaviviruses.

Takeda provides access to the de-identified individual participant data (IPD) for eligible studies to aid qualified researchers in addressing legitimate scientific objectives (Takeda's data sharing commitment is available on https://clinicaltrials.takeda.com/takedas-commitment?commitment=5). These IPDs will be provided in a secure research environment following approval of a data sharing request, and under the terms of a data sharing agreement.

IPD from eligible studies will be shared with qualified researchers according to the criteria and process described on https://vivli.org/ourmember/takeda/. For approved requests, the researchers will be provided access to anonymized data (to respect patient privacy in line with applicable laws and regulations) and with information necessary to address the research objectives under the terms of a data sharing agreement.