The World Health Organization estimates that dengue virus causes more than 50 million cases of dengue fever a year. Dengue virus infection is the leading cause of hospitalization and death in children of most tropical Asian countries. There are four different serotypes of dengue virus. Most cases of dengue hemorrhagic fever/dengue shock syndrome are caused by secondary infection with a dengue serotype different from the first serotype the individual was infected with. A vaccine that would be effective in preventing infection by multiple dengue serotypes is desirable. The purpose of this study is to determine the safety of and immune response to two different dengue virus vaccines in individuals who have been previously vaccinated against a different serotype.~This study will last at least 42 days. Participants will be recruited from a database of previous dengue vaccine recipients and will be stratified by the type of vaccine previously received. Participants assigned to Cohort 1 and Cohort 2 will have already been vaccinated with the rDEN4delta30 vaccine. Participants assigned to Cohort 3 will have already been vaccinated with the rDEN2/4delta30(ME) vaccine. Participants in Cohort 4 will have already been vaccinated with the rDEN1delta30 vaccine. Participants in Cohorts 1 and 3 will be randomly assigned to receive either the rDEN1delta30 vaccine or placebo. Participants in Cohorts 2 and 4 will be randomly assigned to receive either the rDEN2/4delta30(ME) vaccine or placebo.~Participants will receive their assigned vaccination on Day 0. Study visits will occur every other day until Day 16, and then at Days 21, 28, and 42. At each visit, blood collection, vital signs measurement, and a physical exam will occur. In addition, participants will be asked to monitor their temperature daily, 3 times a day, from Day 0 to Day 16. Patients will also be asked to enroll in an optional skin biopsy sub-study.
Dengue fever, which is caused by dengue viruses, is a major health problem in subtropical regions of the world. There are four different forms (serotypes) of dengue virus that can cause dengue fever. The purpose of this study is to determine the safety and immune response to a vaccine containing a particular dengue serotype when an individual has been previously vaccinated with a different dengue serotype.