Evaluating the Clinical and Immune Response to Two Dengue Virus Vaccines in Healthy Adults

Dengue is a mosquito-borne flavivirus. There are 4 types of dengue virus (DENV-1, DENV-2, DENV-3, and DENV-4), each of which can cause mild illness to life-threatening disease. The purpose of this study is to evaluate the immunologic and clinical response to two dengue vaccines (rDEN1Δ30 and rDEN2Δ30-7169), given 9 months apart, in healthy adults with no history of previous flavivirus infection. Participants will be randomly assigned to receive the rDEN1Δ30 vaccine or a placebo vaccine at Day 0. Additional study visits will occur at Days 4, 6, 8, 10, 12, 14, 16, 21, 28, 56, 90, 180, and 240. At Day 270, all participants will receive the rDEN2Δ30-7169 vaccine. An inpatient (overnight) stay will occur on Days 274 through 284, with participants being discharged on Day 284, if they meet the study criteria. Additional visits will occur at Days 286, 291, 298, 326, 360, and 450. Study visits will include blood collection and a physical examination. Participants will monitor and record their temperature 3 times a day for several days after each vaccination.