Phase 2a Immunogenicity Study of Hantaan/Puumala Virus DNA Vaccine for Prevention of Hemorrhagic Fever

The purpose of this study is to compare the immune responses of two different doses (1.0 mg and 2.0 mg) and two different dosing schedules (two doses or three doses) of a mixed Hantaan virus (HTNV) and Puumala virus (PUUV) DNA vaccine in healthy participants. To maintain a blind, participants in the two-dose group will receive one dose of normal saline placebo. All of the groups will also receive a booster dose 6 months after first vaccination. The results will help to determine which dose and vaccination schedule will be best to move forward in the vaccine development process.