Clinical efficacy of prophylactic strategy of long-term low-dose acyclovir for Varicella-Zoster virus infection after allogeneic peripheral blood stem cell transplantation*

Association between Antiviral Prophylaxis and Cytomegalovirus and Epstein-Barr Virus DNAemia in Pediatric Recipients of Allogeneic Hematopoietic Stem Cell Transplant

Background: Epstein–Barr virus (EBV) and cytomegalovirus (CMV) infections can have serious consequences during the period of aplasia and lymphopenia following hematopoietic stem cell transplantation (HSCT). Large pediatric cohort studies examining the effect of antiviral prophylaxis against these viruses are scarce. The present study aimed to analyse the potential effect of antiviral prophylaxis (acyclovir and famciclovir) on active post-transplant EBV and CMV infection in a pediatric cohort of allogeneic HSCT recipients. Methods: We used data from the TREASuRE cohort, consisting of 156 patients who had a first allogeneic HSCT, enrolled in four pediatric centers in Canada between July 2013 and March 2017. Follow-up was performed from the time of transplant up to 100 days post-transplant. Adjusted hazard ratio (HR) with 95% confidence intervals (CI) for the association between antiviral prophylaxis with acyclovir and/or famciclovir and EBV and CMV DNAemia was estimated using multivariate Cox regression models. Results: The post-transplant cumulative incidence of EBV and CMV DNAemia at 100 days of follow-up were, respectively, 34.5% (95% CI: 27.6–42.6) and 19.9% (95% CI: 14.5–27.1). For acyclovir, the adjusted hazard ratio (HR) for CMV and EBV DNAemia was 0.55 (95% CI: 0.24–1.26) and 1.41 (95% CI: 0.63–3.14), respectively. For famciclovir, the adjusted HR were 0.82 (95% CI: 0.30–2.29) and 0.79 (95% CI: 0.36–1.72) for CMV and EBV DNAemia, respectively. Conclusion: The antivirals famciclovir and acyclovir did not reduce the risk of post-transplant CMV and EBV DNAemia among HSCT recipients in our pediatric population.

Safety and reactogenicity of the recombinant zoster vaccine after allogeneic hematopoietic cell transplantation

Allogeneic hematopoietic cell transplantation (HCT) recipients are at increased risk for varicella zoster virus (VZV) reactivation and associated complications. A nonlive adjuvanted recombinant zoster vaccine (RZV) has been developed to prevent herpes zoster (HZ), but there are no recommendations for use in this population. In this single-center prospective observational cohort study, we assessed the safety and reactogenicity of RZV, as well as incidence of graft-versus-host disease (GVHD) and confirmed cases of HZ after vaccination. Between December of 2018 and June of 2020, patients aged ≥18 years received 2 doses of RZV between 9 and 24 months after HCT, with the doses separated by ≥8 weeks. One hundred and fifty-eight patients (mean age, 55 years; 42% women) received ≥1 dose (total vaccinated cohort), and 150 patients (95%) received 2 doses (modified total vaccinated cohort). Solicited reactions occurred in 92.1% of patients (grade 3, 32.5%), owing mostly to injection site pain, which occurred in 86% (grade 3, 16%). The cumulative incidence of GVHD in the peri-vaccination period was no different than in historical controls (adjusted incidence rate ratio, 1.05; 95% confidence interval, 0.8-1.38). There were 4 cases of HZ in the total vaccinated cohort (2.5%) and 3 cases in the modified total vaccinated cohort (28.3/1000 person-years). Among recipients of allogeneic HCT, RZV was safe, tolerable, and did not increase rates of GVHD. Future clinical trials are needed to determine the immunogenicity and efficacy of RZV in this population.

Severe Herpes Zoster Requiring Intravenous Antiviral Treatment in Allogeneic Hematopoietic Cell Transplantation Recipients on Standard Acyclovir Prophylaxis

Allogeneic hematopoietic cell transplantation (HCT) recipients are at increased risk for varicella zoster virus (VZV) reactivation and associated complications. The incidence, timing, and risk factors for severe herpes zoster (HZ) are not well described in the era of acyclovir (ACV) prophylaxis. We performed a retrospective cohort study of all patients who underwent first allogeneic HCT between October 2006 and December 2015 at our institution. Patients were followed until December 2017 for the development of severe HZ, defined as necessitating administration of i.v. antiviral medication. Out of 2163 patients who underwent allogeneic HCT, 22 (1.0%) developed severe HZ at a rate of 1 per 228 person-years, including dermatomal/multidermatomal disease (n = 5), disseminated skin disease (n = 5), HZ ophthalmicus (n = 4), meningitis/encephalitis (n = 4), pneumonia (n = 2), viremia (n = 1), and erythema multiforme (n = 1). Severe HZ infection occurred in a bimodal distribution during the early peri-HCT period and at 12 to 24 months post-HCT (median, 12.7 months). Twelve patients (54.5%) were compliant with ACV prophylaxis at the time of HZ diagnosis. Eleven patients (50%) died during the study period, only 2 of whom (9.1%) with active VZV infection. Mortality was higher in patients on immunosuppressive therapy (62.5% versus 16.7%; P = .045) and with concurrent graft-versus-host disease (75.0% versus 35.7%; P= .044). These data suggest that severe HZ remains an important consideration despite ACV prophylaxis.

Effectiveness of acyclovir prophylaxis against varicella zoster virus disease after allogeneic hematopoietic cell transplantation: A systematic review and meta-analysis

BACKGROUND

Varicella zoster virus (VZV) disease is a common complication after hematopoietic cell transplantation (HCT). The mortality rate for disseminated VZV infection is 34%. Acyclovir has been used for the prophylaxis of VZV disease after HCT, but the effectiveness of prophylaxis is controversial. We conducted a meta-analysis of the incidence of VZV disease within the first 1 year after acyclovir prophylaxis had been discontinued and assessed the risk of VZV disease during acyclovir prophylaxis.

METHODS

Medline, EMBASE plus EMBASE classics, and the Cochrane Central Register of Controlled Trials were used for a systematic search. The inclusion criteria were both randomized controlled trials and cohort studies that described the effectiveness of acyclovir as prophylaxis against VZV disease after allogeneic HCT.

RESULTS

We included seven studies involving a total of 2265 patients. No mortality by VZV was identified. Acyclovir prophylaxis significantly reduced the rate of VZV infection within the first 1 year after discontinuation (risk ratio: 0.38, 95% confidence interval (CI): 0.29-0.51). The risk of VZV disease during acyclovir prophylaxis was also reduced (risk ratio: 0.17, 95% CI: 0.12-0.24). Both short-term and long-term prophylaxis reduced the incidence of VZV infection (RR: 0.51, 95% CI: 0.30-0.86 vs RR: 0.34, 95% CI: 0.22-0.54). Low-dose acyclovir (<400 mg/d) is sufficient to reduce the risk of VZV disease.

CONCLUSION

This study showed that acyclovir prophylaxis reduced VZV infection after HCT with no fatal cases and acyclovir prophylaxis is beneficial. No significant adverse effects occurred and no delayed VZV disease was identified.

Infectious complications after hematopoietic stem cell transplantation: current status and future perspectives in Korea

Hematopoietic stem cell transplantation (HSCT) is a treatment for hematologic malignancies, immune deficiencies, or genetic diseases, ect. Recently, the number of HSCTs performed in Korea has increased and the outcomes have improved. However, infectious complications account for most of the morbidity and mortality after HSCT. Post-HSCT infectious complications are usually classified according to the time after HSCT: pre-engraftment, immediate post-engraftment, and late post-engraftment period. In addition, the types and risk factors of infectious complications differ according to the stem cell source, donor type, conditioning intensity, region, prophylaxis strategy, and comorbidities, such as graft-versushost disease and invasive fungal infection. In this review, we summarize infectious complications after HSCT, focusing on the Korean perspectives.

Varicella zoster virus infection after allogeneic hematopoietic cell transplantation in children using a relatively short duration of acyclovir prophylaxis: A retrospective study

Although acyclovir prophylaxis against varicella zoster virus (VZV) infection for ≥1 year is recommended after allogeneic hematopoietic cell transplantation (HCT), the emergence of acyclovir-resistant viruses and adverse drug effects cannot be ignored. We investigated the cumulative incidence of VZV infection after allogeneic HCT in children receiving a shorter duration of acyclovir prophylaxis than recommended and evaluated the appropriateness of the short duration of acyclovir prophylaxis.Medical records of 217 children who received allogeneic HCT were retrospectively reviewed until a median of 25 months (range = 1-59 months) after HCT. Acyclovir prophylaxis was given for a median of 9 weeks (range = 3-24 weeks) after HCT.VZV infection was diagnosed in 33 (15.2%) children at a median time of 5 months (range = 2-41 months) after HCT. The 1-year and 2-year cumulative incidences of VZV infection after allogeneic HCT were 11.2% and 15.5%, respectively. These incidences were between the previously reported 1-year incidence of 25% to 30% in patients not receiving prophylaxis and 1-year incidence of 4% to 5% in patients receiving ≥1 year duration of prophylaxis. Male sex and older age were significantly associated with VZV infection after allogeneic HCT. Only 1 chickenpox patient experienced severe complications because of VZV infection, and there were no deaths attributable to VZV infection.In conclusion, a shorter duration of acyclovir prophylaxis may be appropriate for children receiving allogeneic HCT, based on the rare occurrence of severe complications because of VZV infection and the expected discomfort because of daily oral medication for a long time.

Antiviral prophylaxis for preventing herpes zoster in hematopoietic stem cell transplant recipients: A systematic review and meta-analysis

The optimal duration of prophylaxis for the varicella-zoster virus following hematopoietic stem cell transplantation (HSCT) remains unclear. The purpose of this study was to systematically review the available literature to determine the optimal duration of antiviral prophylaxis for preventing herpes zoster (HZ) in allogeneic and autologous HSCT recipients. The MEDLINE and EMBASE databases were searched to identify relevant studies. The relative risk (RR) of HZ was calculated using fixed effects or random effects models depending on heterogeneity across the included studies. We analyzed six observational studies comprising a total of 3420 patients. In all HSCT recipients, the overall incidence of HZ in the prophylaxis group and the control group was 7.8% and 25.6%, respectively, with a pooled RR of 0.31 (95% CI, 0.26-0.37). The incidence of HZ in the subgroup wherein prophylaxis was given for at least 1 year and in the subgroup wherein prophylaxis was given for less than 1 year was 2.1% and 15.4%, respectively, with a pooled RR of 0.23 (95% CI, 0.04-1.39). Taken together, our results demonstrate that antiviral prophylaxis can significantly reduce HZ in HSCT recipients, and suggests that long-term prophylaxis given for at least 1 year may be recommended for better preventive effects.

Herpes Zoster in Autologous Hematopoietic Cell Transplant Recipients in the Era of Acyclovir or Valacyclovir Prophylaxis and Novel Treatment and Maintenance Therapies

The epidemiology of herpes zoster (HZ) in contemporary autologous hematopoietic cell transplant (HCT) recipients, and the impact of acyclovir (ACV)/valacyclovir (VACV) prophylaxis, is not well described. In this observational study from 2002 to 2010, we retrospectively identified 1000 varicella zoster virus (VZV)-seropositive autologous HCT recipients with up to 5 years of follow-up. The incidence of HZ and use of ACV/VACV prophylaxis were determined through review of medical records and mailed questionnaires. Risk factors for HZ were determined by multivariable Cox regression. Over a period of 5 years after autologous HCT, 194 patients developed at least 1 HZ episode, with a cumulative incidence of 21%; 159 of 194 (82%) were not on prophylaxis at the time of HZ. A second episode of HZ occurred in 31 of 194 (16%) patients. Patients taking ACV/VACV had reduced risk for HZ (adjusted hazard ratio [aHR], .59; 95% confidence interval [CI], .37 to .91), whereas those older than the median age (≥55.5 years) had increased risk (aHR, 1.42; 95% CI, 1.05 to 1.9). Disseminated VZV was reported in 8% and postherpetic neuralgia in 13% of patients. We demonstrate a high burden of HZ late after autologous HCT, despite long-term antiviral prophylaxis. Improved prevention strategies are needed to provide sustained protection against HZ after autologous HCT.

Predicting risk factors for varicella zoster virus infection and postherpetic neuralgia after hematopoietic cell transplantation using ordered logistic regression analysis

To identify risk factors for varicella zoster virus (VZV) infection and postherpetic neuralgia (PHN) after hematopoietic cell transplantation (HCT), we conducted a retrospective chart review of 163 consecutive patients who underwent HCT between November 2004 and July 2014. Overall, the male/female (M/F) ratio was 80/83, median age at HCT was 54 (range 15-69) years, and autologous/allogeneic HCT (auto/allo-HCT) ratio was 71/92. Forty-four patients [M/F, 25/19; median age, 57 (range: 16-68) years; auto/allo-HCT, 26/18] developed VZV infection after HCT. All cases were successfully treated with acyclovir (ACV) or valacyclovir, and there was no VZV-related death. Nine (20%) of the 44 patients [M/F, 5/4; median age, 58 (range: 21-63) years; auto/allo-HCT, 7/2] developed PHN after resolution of zoster. Multivariate ordered logistic analysis identified receiving immunosuppressive therapy at the cessation of ACV [odds ratio (OR) = 74.53; 95% confidence interval (CI) = 6.99-794.32; P = 0.0004] as a risk factor for VZV infection and PHN in allo-HCT recipients. However, in auto-HCT recipients, only advanced age was identified as a risk factor (OR = 1.06, 95% CI = 1.002-1.127, P = 0.0429). Our findings indicate receiving immunosuppressive therapy at the cessation of ACV is a significant risk factor for allo-HCT recipients, while advanced age is a significant risk factor for auto-HCT recipients.

Infectious diseases in allogeneic haematopoietic stem cell transplantation: prevention and prophylaxis strategy guidelines 2016

Infectious complications after allogeneic haematopoietic stem cell transplantation (allo-HCT) remain a clinical challenge. This is a guideline provided by the AGIHO (Infectious Diseases Working Group) of the DGHO (German Society for Hematology and Medical Oncology). A core group of experts prepared a preliminary guideline, which was discussed, reviewed, and approved by the entire working group. The guideline provides clinical recommendations for the preventive management including prophylactic treatment of viral, bacterial, parasitic, and fungal diseases. The guideline focuses on antimicrobial agents but includes recommendations on the use of vaccinations. This is the updated version of the AGHIO guideline in the field of allogeneic haematopoietic stem cell transplantation utilizing methods according to evidence-based medicine criteria.

Immunity and the burden of herpes zoster

The burden of herpes zoster may be related to patients' immunity, although this has not been studied extensively. This hypothesis was tested in a matched case-control study of patients with herpes zoster who sought treatment at one of seven university hospitals in Korea from January 1, 2007, to December 31, 2010. Patients diagnosed with herpes zoster were placed into three groups based on their immune status: severely immunocompromised, mild-to-moderately immunocompromised, and normal immunity. Each patient in the severely immunocompromised group was matched with one patient in the mild-to-moderately immunocompromised group and one patient in the normal immunity group in the same hospital based on age, sex, and date of herpes zoster onset. A total of 582 patients with herpes zoster were included in the analysis: 194 in each of the three groups. Patients in the severely immunocompromised group had the highest herpes zoster-related hospitalization rate as compared to patients in the mild-to-moderately immunocompromised and normal immune groups (P < 0.01). The length of hospital stay and herpes zoster-related medical cost increased significantly with the deterioration of patients' immunity (P < 0.01, respectively). Cutaneous complications occurred more frequently in the severely immunocompromised group than in the other two groups (P < 0.01). An increase in herpes zoster burden was observed as the patients' immunity decreased. Therefore, effective measures are necessary to prevent herpes zoster and reduce its burden in severely immunocompromised patients.

Eczema herpeticum with herpetic folliculitis after bone marrow transplant under prophylactic acyclovir: are patients with underlying dermatologic disorders at higher risk?

We present an unreported coexistence: eczema herpeticum (EH) with histopathological findings of herpetic folliculitis (HF) after allogeneic bone marrow transplantation (BMT). A patient with atopic dermatitis (AD) underwent allogeneic BMT for idiopathic acquired aplastic anemia. She had been receiving cyclosporine (150 mg/12 h) and acyclovir (400 mg/12 h) for 6 months. A facial rash was observed, composed of monotonous erythematous, umbilicated papulo-vesicles and papulo-crusts <4 mm in size. The histopathological study showed herpetic cytopathic changes within the epidermis that extended into the hair follicle epithelium. Interestingly, microscopic HF has not previously been associated with post-transplant patients or EH. However, it is reasonable to hypothesize that the coexistence of these herpes simplex virus-related events may be underreported in the literature. Although further studies are necessary, we suggest that the prophylactic antiviral dose after BMT be enhanced in patients with underlying dermatologic diseases, especially in those with AD.

Aciclovir and varicella-zoster-immunoglobulin in solid-organ transplant recipients

Clear recommendations for the management of acute varicella-zoster virus (VZV) infections for cases of significant exposure and the use of prophylactic drugs after solid-organ transplantation are missing due to the lack of evidence by prospective studies. Heterogeneity in patient groups, patient numbers, age groups, immunosuppressive regimens, timing, and dosage of aciclovir and/or varicella-zoster immunoglobulin (VZIG), pre-transplant vaccination or VZV wild-type infection and inconsistency of data make comparability of different studies impossible. Although the benefit of aciclovir and/or VZIG is uncertain in immunosuppressed children, prospective controlled double-blind studies are not feasible for ethical considerations as fatal cases with disseminating varicella disease are well known in these patient groups despite the use of aciclovir and/or VZIG, whereas severe side-effects of these drugs are rare. However, a reporting bias is likely as mainly severe or fatal cases might have been predominantly published or cases of successfully used aciclovir and/or VZIG in mild cases or in cases of breakthrough infections after vaccination. As neither VZIG prophylaxis nor treatment with intravenous aciclovir offers complete protection against severe VZV infection to immunosuppressed pediatric solid-organ transplant recipients, high priority should be given to vaccination against VZV prior to transplantation, and, most importantly, in their close contact persons. Clinical observations suggest that only assessment of humoral immunity together with cellular immunity may allow predication about protection in exposed patients.

Shingles vaccine

IMPORTANCE OF THE FIELD

Herpes zoster or shingles is a condition with the potential to result in severe debilitation. It affects approximately 10 - 30% of the population. Until recently there were only treatments to shorten the duration and lessen the symptoms of herpes zoster, but no practical or approved method of prevention for susceptible immunocompetent adults. The live attenuated zoster vaccine (Zostavax, Merck & Co., Inc.) is effective in preventing shingles in individuals 60 years of age and older and recommended by the Center for Disease Control's (CDC) Advisory Committee for Immunization Practices (ACIP).

AREAS COVERED IN THIS REVIEW

Literature related to the live attenuated zoster vaccine is reviewed from its beginnings in the early 1970s through to the present.

WHAT THE READER WILL GAIN

Background information on herpes zoster and up to date information on the live attenuated zoster vaccine including pharmacology, efficacy and safety are covered. New areas of research in zoster vaccination are also discussed.

TAKE HOME MESSAGE

The live attenuated zoster vaccine is an effective and well-tolerated method of preventing zoster and the potentially debilitating sequelae and is recommended for immunocompetent patients 60 years of age and older. Ongoing clinical trials are investigating new means of effective prevention.