Current Role of Prospective Monitoring and Preemptive and Prophylactic Therapy for Human Herpesvirus 6 After Allogeneic Stem Cell Transplantation

Human herpesvirus 6 (HHV-6) frequently reactivates after allogeneic stem cell transplantation (SCT). Most patients are asymptomatic and viremia often resolves without therapy; however, transplant-related complications may be associated with reactivation. Multiple presentations have been attributed to HHV-6 reactivation after SCT including encephalitis. Several strategies have been trialed to reduce such risks or complications. Challenges exist with prospective monitoring strategies, and established thresholds of high-level reactivation may be limited. Three published guidelines and extensive trials focusing on preemptive and prophylactic strategies are reviewed. Future areas of investigation and high-risk populations are described. Existing trials and testing platforms have significant limitations, and to date no clear benefit for a preemptive or prophylactic intervention has been demonstrated. The role of human herpesvirus 6 monitoring and preemptive/prophylactic therapy is controversial after stem cell transplantation. Current guidelines and the most up-to-date literature do not support routine practice; it should be carefully considered if undertaken in the highest-risk patient populations.