PREVAIL VI: Identification of Host Genetic Factors Underlying Ebola Virus Disease Risk, Mortality, Long-Term Sequelae, Viral RNA Persistence, Humoral Immunity, and Ebola Vaccine Response is a case-control study to identify host genetic factors that underlie the observed variation in Ebola virus disease (EVD) susceptibility, severity, clinical sequelae, viral persistence, and serological response. Demographic information, HIV/syphilis status, medical history, and a blood sample will be collected from EVD survivors, close contacts of survivors, EVD healthcare workers, and individuals who received investigational Ebola vaccines. This study will also use blood samples from up to 500 fatal EVD cases. Results may provide insight into pathogenesis and host immunity and potentially suggest new methods of intervention.