A Phase II Trial of a Live Attenuated Virus Tetravalent Dengue Vaccine in Healthy Adults in Thailand

This descriptive study will evaluate the safety and immunogenicity of different formulations of the WRAIR dengue vaccine compared to a placebo.

Subjects will be randomized into one of three groups. One group will receive a placebo vaccine and the other two will receive different dengue vaccine formations. Each subject will receive two doses six months apart. All subjects will have 11 venipunctures during 11 visits (i.e., screening plus 10 study visits) over a period of nine months.

Eligibility Criteria:
Inclusion Criteria:

* A healthy male or female adult 20-25 years of age (≥20 years of age and ≤25 years of age) at the time of vaccination;
* Free of obvious health problems as established by medical history and physical examination before entering into the study;
* Written informed consent obtained from the subject;
* Able to read the Subject Information Sheet and Consent Form;
* Subjects who the investigator believes can and will comply with the requirements of the protocol (e.g., completion of the diary cards, return for follow-up visits) should be enrolled in the study;
* females must be of non-childbearing potential, i.e. surgically sterilized or, if of childbearing potential, she must be abstinent or on adequate contraceptive precautions (i.e. intrauterine contraceptive device; oral contraceptives or other equivalent hormonal contraception, e.g. progestin implantable, cutaneous hormonal patch or injectable contraceptives) for 30 days prior to vaccination, have a negative pregnancy test within 48 hours prior to vaccination and must agree to continue such precautions for 60 days after completion of the vaccination series

Exclusion Criteria:

* Pregnant or lactating female, planning to become pregnant or planning to discontinue abstinence or contraceptive precautions;
* History of any neurological or behavioral disorder or seizures, with the exception of a single febrile seizure in childhood;
* History of drug abuse or alcohol consumption (more than 2 drinks per day);
* History of allergic disease/reaction likely to be exacerbated by any component of the vaccine;
* Acute or chronic, pulmonary, cardiovascular, hepatic, renal, hematologic or endocrine functional defect, as determined by physical examination or laboratory tests;
* Any confirmed or suspected immunosuppressive or immunodeficient condition or seropositive for HBsAg, anti-HCV or anti-HIV;
* Acute disease at the time of enrollment (acute disease is defined as the presence of a moderate or severe illness with or without fever);
* Chronic hepatomegaly, right upper quadrant abdominal pain or tenderness;
* Chronic splenomegaly, left upper quadrant abdominal pain or tenderness;
* Hypertension; chest pain, palpitations, dizziness, shortness of breath, arrhythmias or friction rubs;
* Use of any investigational or non-registered drug or vaccine other than the study vaccine within 30 days preceding the study vaccine (includes placebo) or planned use during the study period;
* Planned administration of a vaccine not foreseen by the study protocol during the period starting from 30 days before the first dose of the study vaccine/placebo and ending 30 days after the second dose;
* A planned move to a location that will prohibit participating in the trial for 9 months after the initial vaccination;
* Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within 90 days preceding the first dose or planned administration during the study period. For corticosteroids, this will mean prednisone, or equivalent, 0.5 mg/kg/day. Inhaled and topical steroids are allowed;
* Administration of immunoglobulins and/or blood products within 90 days preceding the first dose or planned administration during the study period;
* Any chronic systemic drug therapy to be continued during the study period (except for vitamin/mineral supplements or routine treatment for gastro-esophageal reflux);
* No easy access to a fixed or mobile telephone