Dengue viruses cause dengue fever, as well as the more severe dengue hemorrhagic fever/shock syndrome. More than 2 billion people living in tropical and subtropical regions of the world are at risk of dengue virus infection, which is the leading cause of hospitalization and death in children in several tropical Asian countries. This study will evaluate the safety and immunogenicity of a live attenuated dengue virus vaccine called rDEN2/4delta30(ME), which is derived from the DEN2 and DEN4 serotypes.~This study will last 180 days. Participants in Cohort 1 will be randomly assigned to receive rDEN2/4delta30(ME) or placebo at study entry. Cohort 2 will begin only after safety review of all participants in Cohort 1. Participants in Cohort 2 will receive a higher dose of rDEN2/4delta30(ME) or placebo.~After vaccination, participants will be observed for at least 30 minutes for immediate adverse reactions. Participants will also be asked to monitor their temperature every day for 16 days. Study visits will occur every other day after vaccination until Day 16, followed by 4 additional visits at selected days through Day 180. Blood collection and a targeted physical exam will occur at each study visit. Some participants will be asked to undergo a skin biopsy or additional blood collection at selected visits.
Dengue fever, which is caused by dengue viruses, is a major health problem in tropical and subtropical regions of the world. The purpose of this study is to test the safety of and immune response to a new dengue virus vaccine in healthy adults.