The dengue virus causes approximately 50 million cases of dengue fever and 1.5 million cases of the more severe diseases dengue hemorrhagic fever (DHS) and dengue shock syndrome (DSS) every year. There are four subtypes of the virus, and infection with one offers no protection from infection by the others. In fact, most cases of DHS and DSS occur in people infected by more than one subtype. In areas of the world where multiple subtypes of dengue are common, vaccines must be developed against each of the subtypes of dengue virus. This study will examine the safety and immune response of an investigational vaccine for preventing infection with DEN1.~Participation in this study will last about 6 weeks. Participants will be randomly assigned to be injected with either the investigational study vaccine or a placebo. Participants will have a five in six chance of receiving the vaccine. The first study visit will take place on the vaccination day, on which participants will undergo a physical examination, blood draw, and pregnancy test, and then receive the vaccine. Participants will be given a thermometer and temperature card, and be told to record their temperature three times per day for 16 days after vaccination. Participants will come to follow-up visits every other day for the 16 days after vaccination, and then 3, 4, and 6 weeks after vaccination (Days 21, 28, and 42). Assessments completed during these visits will include a questionnaire about how the participant is feeling, pregnancy test, review of temperature cards, blood draw, and physical exam. Blood drawn will be analyzed to check participants' health, determine the amount of vaccine and antibodies in the blood, test markers in white blood cells and genes, and look for proteins that are important for fighting dengue infection.
Dengue viruses can cause dengue fever and other serious health conditions, primarily affecting people living in tropical regions of the world. There are four types of dengue virus, and infection with one does not offer protection against the others. This study will test whether a vaccine developed to prevent infection with dengue virus type 1 (DEN1) causes a response in people's immune system and is safe.