Dengue viruses cause dengue fever and the more severe condition, dengue hemorrhagic fever/shock syndrome. Dengue viruses are common in most tropical and subtropical regions of the world and infection with dengue viruses is the leading cause of hospitalization and death in children in many tropical Asian countries. For these reasons, the World Health Organization (WHO) has made the development of a dengue virus vaccine a top priority. This study will evaluate the safety and immunogenicity of five versions of a live, attenuated, tetravalent dengue virus vaccine called TetraVax-DV.~This study will enroll healthy adults 18-50 years old. Participants will be randomly assigned to receive one of the five versions of TetraVax-DV or placebo. At the vaccination study visit, participants will undergo a medical history review, physical examination, blood and urine collection, and vital sign measurements. Participants will then receive one injection of their assigned vaccine or placebo in the upper arm. After receiving the vaccine, participants will remain in the clinic for 30 minutes for observation. At home, participants will monitor and record their temperature three times a day for 16 days. Additional study visits will occur at Days 2, 4, 6, 8, 10, 12, 14, 16, 21, 28, 42, and 180 for physical exams, assessment of symptoms, and blood and urine collection. Some participants will attend an additional study visit at Day 60.~Participants who received one of the five versions of the vaccine will be asked to take part in an optional substudy that will evaluate the safety and immunogenicity of a second vaccination 6 months after the first vaccination. In the substudy, participants will be randomly assigned to receive either the same vaccine they received in the first part of the study or a placebo vaccine. For 6 months following the second vaccination, participants will attend study visits and take part in the same study procedures that occurred in the first part of the study.
Dengue viruses can cause dengue fever and other serious health conditions, primarily affecting people living in tropical regions of the world. This study will evaluate the safety and immune responses of five formulations of a tetravalent dengue virus vaccine in healthy adults.