Viral infection Long-term low-dose acyclovir against varicella-zoster virus reactivation after allogeneic hematopoietic stem cell transplantation

Summary:To evaluate the efficacy of long-term administration ofacyclovir as prophylaxis against varicella-zoster virus(VZV) reactivation, we analyzed the medical records of86 consecutive adult patients who obtained engraftmentafter allogeneic hematopoietic stem cell transplantationfrom January 1996 to March 2000. We started long-term low-dose (400 mg/day) oral administration of acy-clovir in June 1999, and this was continued until theend of immunosuppressive therapy after transplan-tation. There was no breakthrough reactivation of VZVin patients receiving acyclovir. Five patients who werereceiving cyclosporine or prednisolone developed VZVreactivation after discontinuing acyclovir. With thisprophylaxis, the cumulative incidence of VZV reacti-vation at 1 year after transplantation decreased from33% to 10% ( P = 0.025). On multivariate analysis, theuse of long-term acyclovir was identified as a significantindependent parameter for the development of VZVreactivation. These findings suggest the efficacy of long-term prophylaxis with low-dose acyclovir. Resumptionof acyclovir upon restarting immunosuppressive ther-apy might be important for the further prevention ofVZV reactivation. The benefit of long-term low-doseacyclovir should be confirmed prospectively.