Evaluating the Safety and Immune Response to Two Admixtures of a Tetravalent Dengue Virus Vaccine

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 two doses of a live, attenuated, tetravalent dengue virus vaccine called TetraVax-DV in healthy adults. Two different versions of the TetraVax-DV vaccine will be evaluated. This study will enroll healthy adults 18-50 years old. Participants will be randomly assigned to receive one of two admixtures of the TetraVax-DV vaccine or a placebo. At a baseline study visit, participants will undergo a medical history review, physical examination, blood collection, vital sign measurements, and a pregnancy test for females. Participants will then receive one injection of their assigned vaccine in the upper arm. After receiving the vaccine, participants will remain in the clinic for 30 minutes for observation and monitoring. At home, participants will monitor and record their temperature three times a day for 16 days. Additional study visits will occur at Days 3, 8, 10, 12, 14, 16, 21, 28, 56, 90, and 150 and will include a physical examination, assessment of symptoms, and blood collection. On Day 180, participants will receive a second injection of the same vaccine they received at the baseline study visit. Follow-up study visits will occur at Days 183, 188, 190, 192, 194, 196, 201, 208, 236, 270, and 360, and will include the same study procedures and monitoring that occurred after the first vaccination.