Low-dose acyclovir prophylaxis for the prevention of herpes simplex virus and varicella zoster virus diseases after autologous hematopoietic stem cell transplantation.

Limited data are available on prophylaxis for herpes simplex virus (HSV) and varicella zoster virus (VZV) disease following autologous hematopoietic stem cell transplantation (auto-HCT). We retrospectively reviewed the clinical charts of 105 consecutive patients who underwent their first auto-HCT at our institution between September 2007 and June 2014. Before August 2009, 30 patients received oral acyclovir at 1000 mg/day until engraftment, whereas after September 2009, 69 patients received oral acyclovir at 200 mg/day. After engraftment, acyclovir was continued at 200 mg/day at the discretion of the attending physicians in both groups. The cumulative incidence of HSV disease at 1 year after auto-HCT was 7.7 and 4.5 % in patients who received oral acyclovir at 1000 and 200 mg/day, respectively (P = 0.75). Patients were next divided into three groups according to the timing at which acyclovir prophylaxis was stopped after auto-HCT; at engraftment, between engraftment and 1 year after auto-HCT, and later than 1 year. The cumulative incidence of VZV disease was 25.8, 7.7, and 0.0 % at 1 year, respectively. This study suggests that low-dose acyclovir prophylaxis may be effective for preventing HSV and VZV disease after auto-HCT. Our findings support the recommendation of acyclovir prophylaxis within the first year after auto-HCT.