Effect of oral acyclovir against primary and secondary viraemia in incubation period of varicella

A quick algorithmic review on management of viral infectious diseases in pediatric solid organ transplant recipients

Pediatric solid organ transplant is a life-saving procedure for children with end-stage organ failure. Viral infections are a common complication following pediatric solid organ transplantation (SOT), which can lead to increased morbidity and mortality. Pediatric solid organ transplant recipients are at an increased risk of viral infections due to their immunosuppressed state. The most commonly encountered viruses include cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus (HSV), varicella-zoster virus (VZV), adenoviruses, and BK polyomavirus. Prevention strategies include vaccination prior to transplantation, post-transplant prophylaxis with antiviral agents, and preemptive therapy. Treatment options vary depending on the virus and may include antiviral therapy and sometimes immunosuppression modification. This review provides a Quick Algorithmic overview of prevention and treatment strategies for viral infectious diseases in pediatric solid organ transplant recipient.

PEPtalk 3: oral aciclovir is equivalent to varicella zoster immunoglobulin as postexposure prophylaxis against chickenpox in children with cancer - results of a multicentre UK evaluation

OBJECTIVE

To compare the occurrence of chickenpox in children with cancer who received varicella immunoglobulin (VZIG) or aciclovir as postexposure prophylaxis (PEP).

DESIGN

Prospective multicentre service evaluation of children with cancer who received either VZIG or aciclovir as PEP following significant exposure to varicella zoster virus (VZV) over a 24-month period from May 2018.

SETTING

Data were collected from 9 UK Paediatric Oncology Primary Treatment Centres.

PATIENTS

Children under 16 years old with a diagnosis of cancer and/or previous haematopoietic stem cell transplant who were VZV seronegative at exposure and/or diagnosis and received PEP following significant VZV exposure.

MAIN OUTCOME MEASURES

The primary outcome was the incidence of breakthrough varicella within 6 weeks of VZV exposure and treatment with PEP.

RESULTS

A total of 105 eligible patients were registered with a median age of 4.9 years (range 1.1-10.5 years). Underlying diagnoses were acute leukaemia (64), solid tumours (22), Langerhans cell histiocytosis (9), central nervous system (CNS) tumours (8) and other (2). Aciclovir was received by 86 patients (81.9%), 18 received VZIG (17.1%) and 1 valaciclovir (0.9%). There were seven reported break-through VZV infections in 103 patients at follow-up (7/103, 6.8%). Clinical VZV developed in 5/84 of the aciclovir group (6.0%, 95% CI 2.0 to 13.3) and 2/18 of VZIG group (11.1%, 95% CI 1.4 to 34.7). All breakthrough infections were either mild (5/7) or moderate (2/7) in severity.

CONCLUSION

Aciclovir is a safe and effective alternative to VZIG as VZV PEP in children with cancer and should be considered as standard of care.

Antiviral therapy for COVID-19: Derivation of optimal strategy based on past antiviral and favipiravir experiences

Favipiravir, a broad-spectrum RNA-dependent RNA polymerase inhibitor, inhibits the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at significantly lower concentrations than the plasma trough levels achieved by the dosage adopted for influenza treatment and exhibits efficacy against coronavirus disease 2019 (COVID-19) pneumonia. Although high doses of favipiravir are required due to the molecule being a purine analog, its conversion into the active form in infected cells with active viral RNA synthesis enhances the antiviral specificity and selectivity as a chain terminator with lethal mutagenesis. Another characteristic feature is the lack of generation of favipiravir-resistant virus. COVID-19 pneumonia is caused by strong cell-mediated immunity against virus-infected cells, and the inflammatory response induced by adaptive immunity continues to peak for 3 to 5 days despite antiviral treatment. This has also been observed in herpes zoster (HZ) and cytomegalovirus (CMV) pneumonia. Inflammation due to an immune response may mask the effectiveness of favipiravir against COVID-19 pneumonia. Favipiravir significantly shortened the recovery time in patients with mild COVID-19 pneumonia by 3 days with the start of treatment by the 5th day of symptom onset. Since both CMV and COVID-19 pneumonia are caused by adaptive immunity and prevention of cytomegalovirus pneumonia is the standard treatment due to difficulties in treating refractory CMV pneumonia, COVID-19 pneumonia should be prevented with early treatment as well. In the present study, we have comprehensively reviewed the optimal antiviral therapy for COVID-19 based on clinical trials of favipiravir for the treatment of COVID-19 pneumonia and the concurrently established therapies for other viral infections, particularly HZ and CMV pneumonia. Optimally, antivirals should be administered immediately after COVID-19 diagnosis, similar to that after influenza diagnosis, to prevent COVID-19 pneumonia and complications resulting from microangiopathy.

Effectiveness of oral aciclovir in preventing maternal chickenpox: A comparison with VZIG

OBJECTIVES

Although often presenting as a self-limiting childhood disease, chickenpox can have serious consequences if acquired in pregnancy. Until April 2022, the UK recommendations were that varicella immunoglobulin (VZIG) should be administered intramuscularly to susceptible pregnant women exposed to chickenpox prior to 20 weeks gestation. Oral aciclovir or VZIG was recommended if exposure occurred at 20+ weeks gestation. Our objective was to compare the effectiveness of oral aciclovir to VZIG in preventing maternal and neonatal chickenpox.

METHODS

We identified and followed up 186 pregnant women who were exposed to chickenpox and compared their outcomes.

RESULTS

171/186 (91.9%) of these women received either VZIG or oral aciclovir. Of the 145 women who received VZIG, 53/145 (36.6%) went on to develop chickenpox compared to 8 of the 26 (30.8%) women who received oral aciclovir (p=0.32). No statistical difference was found between the oral aciclovir and VZIG groups even after controlling for maternal age, gestational stage, type of exposure and IgG titre (adjusted OR:0.83; 95%CI:0.26-2.65; p=0.75).

CONCLUSIONS

These findings support the use of oral aciclovir as first-line prophylaxis in pregnant women exposed to varicella as they suggest its effectiveness at preventing maternal chickenpox is either better or equal to VZIG.

Prevention of viral infections in solid organ transplant recipients in the era of COVID-19: a narrative review

INTRODUCTION

In solid organ transplant (SOT) recipients, viral infections are associated with direct morbidity and mortality and may influence long-term allograft outcomes. Prevention of viral infections by vaccination, antiviral prophylaxis, and behavioral measures is therefore of paramount importance.

AREAS COVERED

We searched Pubmed to select publications to review current preventive strategies against the most important viral infections in SOT recipients, including SARS-CoV-2, influenza, CMV, and other herpesvirus, viral hepatitis, measles, mumps, rubella, and BK virus.

EXPERT OPINION

The clinical significance of the reduced humoral response following mRNA SARS-CoV-2 vaccines in SOT recipients still needs to be better clarified, in particular with regard to the vaccines' efficacy in preventing severe disease. Although a third dose improves immunogenicity and is already integrated into routine practice in several countries, further research is still needed to explore additional interventions. In the upcoming years, further data are expected to better delineate the role of virus-specific cell mediated immune monitoring for the prevention of CMV and potentially other viral diseases, and the role of the letermovir in the prevention of CMV in SOT recipients. Future studies including clinical endpoints will hopefully facilitate the integration of successful new influenza vaccination strategies into clinical practice.

Amenamevir, a Helicase-Primase Inhibitor, for the Optimal Treatment of Herpes Zoster

Acyclovir, valacyclovir, and famciclovir are used for the treatment of herpes simplex virus (HSV) and varicella-zoster virus (VZV) infections. Helicase-primase inhibitors (HPIs) inhibit replication fork progression that separates double DNA strands into two single strands during DNA synthesis. The HPIs amenamevir and pritelivir have novel mechanisms of anti-herpetic action, and their once-daily administration has clinical efficacy for genital herpes. Among HPIs, amenamevir has anti-VZV activity. The concentrations of HSV-1 and VZV required for the 50% plaque reduction of amenamevir were 0.036 and 0.047 μM, respectively. We characterized the features of amenamevir regarding its mechanism, resistance, and synergism with acyclovir. Its antiviral activity was not influenced by the viral replication cycle, in contrast to acyclovir. A clinical trial of amenamevir for herpes zoster demonstrated its non-inferiority to valacyclovir. To date, amenamevir has been successfully used in over 1,240,000 patients with herpes zoster in Japan. Post-marketing surveillance of amenamevir in Japan reported side effects with significant potential risk identified by the Japanese Risk Management Plan, including thrombocytopenia, gingival bleeding, and palpitations, although none of these were serious. The clinical efficacy and safety profiles of amenamevir were established in patients with herpes zoster. Therefore, amenamevir as an HPI opens a new era of anti-herpes therapy.

Emergence of varicella-zoster virus resistance to acyclovir: epidemiology, prevention, and treatment

Introduction: Acyclovir has led to the development of successful systemic therapy for herpes simplex virus and varicella-zoster virus (VZV) infection, and the use of valacyclovir and famciclovir has improved treatment. Additionally, the use of a helicase-primase (HP) inhibitor (HPI), amenamevir, is changing the treatment of herpes zoster (HZ).Area covered: VZV infection is prevented by vaccines and is treated with antiviral agents. Acyclovir and penciclovir are phosphorylated by viral thymidine kinase and work as chain terminators. Improvements in the management of immunocompromised patients have reduced severe and prolonged immunosuppression and chronic VZV infection with acyclovir-resistant mutants has become rarer. The HP is involved in the initial step of DNA synthesis and amenamevir has novel mechanisms of action, efficacy to acyclovir-resistant mutants, and pharmacokinetic characteristics. The literature search for PUBMED was conducted on 10 April 2020 and updated on 4 November 2020.Expert opinion: Amenamevir has been used to treat HZ in Japan. Although the number of patients with VZV infection will decrease owing to the use of vaccines, the addition of HPI will improve treatment and treatment options for resistant viruses. The clinical use of HPIs in addition to current nucleoside analogs opens a new era of antiherpes therapy.

Varicella zoster immune globulin (human) (VARIZIG) in immunocompromised patients: a subgroup analysis for safety and outcomes from a large, expanded-access program

Background

Immunocompromised children and adults are at increased risk for severe disease and death following varicella zoster virus infection. Varicella zoster immune globulin (human) (VARIZIG) is recommended for post-exposure prophylaxis to prevent or attenuate varicella infection in high-risk individuals.

Methods

An open-label, expanded-access program provided VARIZIG to high-risk individuals exposed to varicella or herpes zoster. Immunocompromised participants were stratified by type of immunocompromising condition (“oncologic immunodeficiency”, “primary immunodeficiency”, “solid organ transplant” [SOT], “hematopoietic cell transplant” [HCT], and “other”). Patient characteristics, type of exposure and varicella outcome, and safety data were assessed.

Results

This analysis included 40 adults (primary [n = 6] or oncologic [n = 10] immunodeficiencies, history of SOT [n = 5] or HCT [n = 6], and other [n = 13]), and 263 children (primary [n = 13] or oncologic [n = 152] immunodeficiencies, history of SOT [n = 36] or HCT [n = 17], and other [n = 45]). Among adults and children, 48% vs 72% were exposed to varicella, 38% vs 16% were exposed to herpes zoster, and 15% vs 12% had an unspecified exposure. Overall incidence of varicella infection in adults after VARIZIG use was 6%; incidence of varicella infection in children after VARIZIG use was 7%. Similar rates were noted in each subgroup. Most cases of varicella were mild, with two children developing > 100 lesions and no cases of varicella-related pneumonia or encephalitis. Varicella-related hospitalizations occurred primarily in children with oncologic immunodeficiencies. One serious adverse event (serum sickness) was considered related to VARIZIG and occurred in a child with oncologic immunodeficiency. There were no varicella- or VARIZIG-related deaths.

Conclusions

These data indicate that VARIZIG may reduce severity of varicella in immunocompromised children and adults.

Trial registration

This study was retrospectively registered with the public clinical trial identification NCT00338442 at https://www.clinicaltrials.gov on 20 June 2006.

Antiviraux chez l’enfant en pratique de ville : infections herpétiques, varicelle, grippe

Les infections liées à l’herpès virus humain (HSV), au virus de la varicelle et du zona (VZV) et au virus de la grippe (Influenza A et B) sont très fréquentes en pédiatrie et sont le plus souvent bénignes avec une guérison spontanée. L’utilisation des antiviraux antigrippaux (inhibiteurs de neuraminidase) a été étudiée dans de larges essais randomisés et fait l’objet de recommandations nationales et internationales. Celle des anti-HSV et anti-VZV n’a pas fait l’objet d’études de la même ampleur et de ce fait, leur prescription est plus discutée avec des bénéfices moins bien définis et variables (à l’exception des infections néonatales et/ou neuro-méningées). L’objectif de cette mise au point est donc de proposer une synthèse des données disponibles dans la littérature concernant les indications des antiviraux en pratique de ville pour les infections liées à l’HSV (gingivostomatite, herpès récurrent, faux panaris herpétique), au VZV (varicelle, zona) et à la grippe.

Safety and Varicella Outcomes in In Utero-Exposed Newborns and Preterm Infants Treated With Varicella Zoster Immune Globulin (VARIZIG): A Subgroup Analysis of an Expanded-Access Program

BACKGROUND

Infants exposed to varicella zoster virus (VZV) in utero ≤5 days before or ≤48 hours after delivery and preterm infants are at high risk for varicella complications. An expanded-access program assessed varicella outcomes after administration of varicella zoster immune globulin (human) (VARIZIG) in a real-world setting.

METHODS

In this open-label, expanded-access program, high-risk infants received ≤125 IU/10 kg of VARIZIG (NCT00338442). VZV outcomes and safety were assessed.

RESULTS

There were 43 newborns exposed to VZV in utero and 80 preterm infants exposed to VZV; >80% received VARIZIG within 96 hours of reported exposure. When varicella outcomes were available, varicella occurred in 7 of 38 (18%) in utero-exposed newborns and zero of 65 preterm infants. Varicella-related complications were reported in 3 in utero-exposed newborns (3 with >100 lesions, 1 each with encephalitis and pneumonia). Adverse events were reported for 16% of in utero-exposed newborns and 25% of preterm infants, but few were considered related to VARIZIG. There were no deaths attributable to varicella or VARIZIG.

CONCLUSIONS

Varicella incidence and morbidity were low in in utero-exposed infants and zero in preterm infants who received prophylactic VARIZIG. There were few VARIZIG-related safety concerns.

Varicella zoster virus in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the American Society of Transplantation Infectious Diseases Community of Practice review the diagnosis, prevention, and management of varicella zoster virus (VZV) in the pre- and post-transplant period. Primary varicella is an uncommon complication post-solid-organ transplant (SOT), except among pediatric transplant patients and those seronegative for VZV. As the majority of SOT recipients are seropositive for VZV, herpes zoster (HZ) occurs frequently following SOT, particularly among recipients who are older (≥65 years of age) and those receiving more intensive immunosuppression. Transplant providers should aware of the increased risk for HZ-related complications such as dissemination, organ-specific involvement, and post-herpetic neuralgia. Treatment for localized zoster is primarily given as oral regimens, but those with more complicated presentations or those at risk for dissemination should be treated initially with IV therapy. Available antiviral prophylaxis regimens and vaccination strategies for varicella and HZ among these immunosuppressed patients remain a mainstay for prevention in the pre-and post-transplant periods. Finally, we discuss important approaches to addressing post-exposure prophylaxis and infection control practices for those SOT patients with documented VZV infections.

Varicella zoster immune globulin (VARIZIG) administration up to 10 days after varicella exposure in pregnant women, immunocompromised participants, and infants: Varicella outcomes and safety results from a large, open-label, expanded-access program

Introduction

Despite vaccination, there were more than 100,000 annual cases of varicella in the United States in 2013–2014. Individuals at highest risk of developing severe or complicated varicella include immunocompromised people, preterm infants, and pregnant women. Varicella zoster immune globulin (human) (VARIZIG) is recommended by the CDC for postexposure prophylaxis to prevent or attenuate varicella-zoster virus infection in high-risk individuals. Contemporary information on administration of VARIZIG is limited.

Methods

This open-label, expanded-access program provided VARIZIG to physician-identified, high-risk participants exposed to varicella. Participants included immunocompromised children/adults, infants (preterm, newborns whose mothers had varicella onset within 5 days before or 2 days after delivery, and those aged <1 year), and pregnant women. VARIZIG (125 IU/10 kg [up to 625 IU]) was administered intramuscularly, ideally within 96 hours, but up to 10 days, postexposure. Incidence of varicella rash and severity (>100 pox, pneumonia, or encephalitis) were assessed up to 42 days after administration.

Results

The varicella outcome population (n = 507) included 263 immunocompromised participants (32 adults, 231 children), 137 pregnant women, 105 infants, and 2 healthy adults with no history of varicella. Varicella incidence was 4.5% in immunocompromised participants, 7.3% in pregnant women, and 11.5% in infants. The incidence of varicella was similar when comparing VARIZIG administration ≤ 96 hours vs > 96 hours (up to 10 days) postexposure in the entire population (6.2% vs. 9.4%, respectively), and also in each subgroup. Of 34 participants with varicella, 5 developed > 100 pox and 1 developed pneumonia and encephalitis. There were no product-related deaths and only 1 serious adverse event (serum sickness) considered probably related to VARIZIG.

Conclusion

Postexposure administration of VARIZIG was associated with low rates of varicella in high-risk participants, regardless of when administered within 10 days postexposure. VARIZIG was well-tolerated and safe in high-risk participants.

Vaccinations in kidney transplant recipients: Clearing the muddy waters

Vaccine preventable diseases account for a significant proportion of morbidity and mortality in transplant recipients and cause adverse outcomes to the patient and allograft. Patients should be screened for vaccination history at the time of pre-transplant evaluation and vaccinated at least four weeks prior to transplantation. For non-immune patients, dead-vaccines can be administered starting at six months post-transplant. Live attenuated vaccines are contraindicated after transplant due to concern for infectious complications from the vaccine and every effort should be made to vaccinate prior to transplant. Since transplant recipients are on life-long immunosuppression, these patients may have lower rates of serological conversion, lower mean antibody titers and waning of protective immunity over shorter period as compared to general population. Recommendations regarding booster dose in kidney transplant recipients with sub-optimal serological response are lacking. Travel plans should be part of routine post-transplant assessment and pre-travel vaccines and counseling should be provided. More studies are needed on vaccination schedules, serological response, need for booster doses and safety of live attenuated vaccines in this special population.

PEPtalk2: results of a pilot randomised controlled trial to compare VZIG and aciclovir as postexposure prophylaxis (PEP) against chickenpox in children with cancer

OBJECTIVE

To determine the likely rate of patient randomisation and to facilitate sample size calculation for a full-scale phase III trial of varicella zoster immunoglobulin (VZIG) and aciclovir as postexposure prophylaxis against chickenpox in children with cancer.

DESIGN

Multicentre pilot randomised controlled trial of VZIG and oral aciclovir.

SETTING

England, UK.

PATIENTS

Children under 16 years of age with a diagnosis of cancer: currently or within 6 months of receiving cancer treatment and with negative varicella zoster virus (VZV) serostatus at diagnosis or within the last 3 months.

INTERVENTIONS

Study participants who have a significant VZV exposure were randomised to receive PEP in the form of VZIG or aciclovir after the exposure.

MAIN OUTCOME MEASURES

Number of patients registered and randomised within 12 months of the trial opening to recruitment and incidence of breakthrough varicella.

RESULTS

The study opened in six sites over a 13-month period. 482 patients were screened for eligibility, 32 patients were registered and 3 patients were randomised following VZV exposure. All three were randomised to receive aciclovir and there were no cases of breakthrough varicella.

CONCLUSIONS

Given the limited recruitment to the PEPtalk2 pilot, it is unlikely that the necessary sample size would be achievable using this strategy in a full-scale trial. The study identified factors that could be used to modify the design of a definitive trial but other options for defining the best means to protect such children against VZV should be explored.

TRIAL REGISTRATION NUMBER

ISRCTN48257441, EudraCT number: 2013-001332-22, sponsor: University of Birmingham.

Microbiology laboratory and the management of mother-child varicella-zoster virus infection

Varicella-zoster virus, which is responsible for varicella (chickenpox) and herpes zoster (shingles), is ubiquitous and causes an acute infection among children, especially those aged less than six years. As 90% of adults have had varicella in childhood, it is unusual to encounter an infected pregnant woman but, if the disease does appear, it can lead to complications for both the mother and fetus or newborn. The major maternal complications include pneumonia, which can lead to death if not treated. If the virus passes to the fetus, congenital varicella syndrome, neonatal varicella (particularly serious if maternal rash appears in the days immediately before or after childbirth) or herpes zoster in the early years of life may occur depending on the time of infection. A Microbiology laboratory can help in the diagnosis and management of mother-child infection at four main times: (1) when a pregnant woman has been exposed to varicella or herpes zoster, a prompt search for specific antibodies can determine whether she is susceptible to, or protected against infection; (2) when a pregnant woman develops clinical symptoms consistent with varicella, the diagnosis is usually clinical, but a laboratory can be crucial if the symptoms are doubtful or otherwise unclear (atypical patterns in immunocompromised subjects, patients with post-vaccination varicella, or subjects who have received immunoglobulins), or if there is a need for a differential diagnosis between varicella and other types of dermatoses with vesicle formation; (3) when a prenatal diagnosis of uterine infection is required in order to detect cases of congenital varicella syndrome after the onset of varicella in the mother; and (4) when the baby is born and it is necessary to confirm a diagnosis of varicella (and its complications), make a differential diagnosis between varicella and other diseases with similar symptoms, or confirm a causal relationship between maternal varicella and malformations in a newborn.

Incidence and consequences of varicella in children treated for cancer in Guatemala

BACKGROUND

Varicella-zoster virus infection is associated with significant morbidity and mortality in immune-compromised children, despite treatment with antiviral agents. Universal varicella vaccine programs have significantly decreased this risk in many highincome countries, but in most low-income and middleincome countries, the burden of varicella in children treated for malignancy is poorly defined.

METHODS

We retrospectively reviewed records of children at the National Unit of Pediatric Oncology (UNOP) in Guatemala diagnosed with varicella between January 2009 and March 2013 in order to calculate incidence of varicella and evaluate morbidity, mortality, treatment interruption, and cost.

RESULTS

Fifty-nine cases of varicella were identified. Incidence was 23.4 cases per 1000 person-years (p-y). 66.1% of cases occurred in children with leukemia (median age 5.2 years; interquantile range 3.4-7 years) and 41.0% of these occurred during maintenance therapy. Source of exposure was identified for 14/59 (23.7%) children. Most were hospitalized (71.2%) and given intravenous acyclovir (64.4%). Eight (13.6%) children required critical care, and two (3.4%) died from disseminated varicella with multiorgan failure. Chemotherapy was delayed or omitted due to varicella in 50%. No significant differences in outcomes based on nutritional and immunologic status were detected. The minimum average cost of treatment per episode was 598.75 USD.

CONCLUSIONS

Varicella is a significant problem in children treated for cancer in Guatemala, where effective post-exposure prophylaxis is limited. In the absence of universal varicella vaccination, strategies to improve recognition of exposure and the future use of novel inactivated vaccines currently under investigation in clinical trials could mitigate this burden.

Travel vaccination recommendations and endemic infection risks in solid organ transplantation recipients

BACKGROUND

Solid organ transplant (SOT) recipients are often heavily immunosuppressed and consequently at risk of serious illness from vaccine preventable viral and bacterial infections or with endemic fungal and parasitic infections. We review the literature to provide guidance regarding the timing and appropriateness of vaccination and pathogen avoidance related to the immunological status of SOT recipients.

METHODS

A PUBMED search ([Vaccination OR vaccine] AND/OR ["specific vaccine"] AND/OR [immunology OR immune response OR cytokine OR T lymphocyte] AND transplant was performed. A review of the literature was performed in order to develop recommendations on vaccination for SOT recipients travelling to high-risk destinations.

RESULTS

Whilst immunological failure of vaccination in SOT is primarily the result of impaired B-cell responses, the role of T-cells in vaccine failure and success remains unknown. Vaccination should be initiated at least 4 weeks prior to SOT or more than 6 months post-SOT. Avoidance of live vaccination is generally recommended, although some live vaccines may be considered in the specific situations (e.g. yellow fever). The practicing physician requires a detailed understanding of region-specific endemic pathogen risks.

CONCLUSIONS

We provide a vaccination and endemic pathogen guide for physicians and travel clinics involved in the care of SOT recipients. In addition, recommendations based on timing of anticipated immunological recovery and available evidence regarding vaccine immunogenicity in SOT recipients are provided to help guide pre-travel consultations.

Postexposure Prophylaxis Against Varicella-Zoster Virus Infection Among Recipients of Hematopoietic Stem Cell Transplant: Unresolved Issues

Recent guidelines for the prevention of opportunistic infections have addressed a variety of issues germane to recipients of hematopoietic stem cell transplant. However, there are several issues regarding postexposure prophylaxis against varicella-zoster virus that remain unresolved. We address these questions and offer several consensus recommendations.

Molecular diagnosis and management of viral infections in hematopoietic stem cell transplant recipients

Viral infections after allogeneic hematopoietic stem cell transplantation (HSCT) are important complications associated with high morbidity and mortality. In this setting, reactivations of persisting latent viral pathogens from donor and/or recipient cells play a central role whereas the sterile environment of transplant units renders new infections less likely. The viruses currently regarded as most relevant in the HSCT setting include particularly the herpes virus family--specifically cytomegalovirus (CMV), Epstein-Barr virus (EBV), and human herpesvirus 6 (HHV-6)--as well as human adenoviruses (AdVs) and the polyoma virus BK (BKV). Timely detection and monitoring of virus copy numbers are prerequisites for successful preemptive treatment approaches. Pre- and post-transplant surveillance by sensitive and quantitative molecular methods has therefore become an essential part of the diagnostic routine. In this review, we discuss diagnostic aspects and the clinical management of the most important viral infections in HSCT recipients, with a focus on pediatric patients.

Varicella-zoster virus (chickenpox) infection in pregnancy

Congenital varicella syndrome, maternal varicella-zoster virus pneumonia and neonatal varicella infection are associated with serious fetomaternal morbidity and, not infrequently, mortality. Vaccination against varicella-zoster virus can prevent the disease, and outbreak control limits the exposure of pregnant women to the infectious agent. Maternal varicella-zoster immunoglobulin administration before rash development, with or without antiviral medication, can modify the progression of the disease.

Immunisation practices of paediatric oncology and shared care oncology consultants: a United Kingdom survey

BACKGROUND

In March 2002, the Royal College of Paediatrics and Child Health (RCPCH) introduced guidelines for re-immunisation of children after completion of standard-dose chemotherapy and after haematopoietic stem cell transplant (HSCT).

AIMS

To ascertain whether these guidelines form standard unit policy by undertaking a survey of UK paediatric principal treatment centre (PTC) consultants and shared care (SC) consultants.

PROCEDURES

In October 2008, a link to an on-line anonymised survey was sent by e-mail to all UK PTC consultants in Children's Cancer and Leukaemia Group (CCLG) centres and to SC consultants linked to eight of these centres.

RESULTS

Responses were received from 55 PTC consultants (representing all 21 CCLG centres) and 54 SC consultants. In accordance with the RCPCH guidelines, most PTC and SC consultants recommend initiating re-immunisation at 6 months after completion of standard-dose chemotherapy (99/105, 94.3%). Re-immunisation at the recommended time after HSCT for each transplant type was reported by 93-100% of respondents. Pneumococcal conjugate vaccine (PCV) was recommended after chemotherapy by 58.3% (35/60) of respondents and by 51.7% (30/58) after HSCT. There were distinct differences between PTC and SC consultants in their choice of varicella (VZV) post-exposure prophylaxis.

CONCLUSIONS

There is a high level of stated compliance with RCPCH guidelines. Recommendations for PCV after chemotherapy and HSCT were lower than expected. This may reflect the absence of specific guidelines after chemotherapy but not in HSCT patients where guidelines do exist. Variation in VZV post-exposure prophylaxis suggests further studies are required.

Management of HSV, VZV and EBV infections in patients with hematological malignancies and after SCT: guidelines from the Second European Conference on Infections in Leukemia

These guidelines on the management of HSV, VZV and EBV infection in patients with hematological malignancies and after SCT were prepared by the European Conference on Infections in Leukemia following a predefined methodology. A PubMed search was conducted using the appropriate key words to identify studies pertinent to management of HSV, VZV and EBV infections. References of relevant articles and abstracts from recent hematology and SCT scientific meetings were also reviewed. Prospective and retrospective studies identified from the data sources were evaluated, and all data deemed relevant were included in this analysis. The clinical and scientific background was described and discussed, and the quality of evidence and level of recommendation were graded according to the Centers for Disease Control criteria.

Acyclovir for treating varicella in otherwise healthy children and adolescents

BACKGROUND

Acyclovir has the potential to shorten the course of illness which may result in reduced costs and morbidity associated with chickenpox.

OBJECTIVES

1) To examine the evidence evaluating the efficacy of acyclovir in alleviating symptoms of chickenpox and shortening the duration of illness. 2) To examine complications of chickenpox and adverse effects associated with acyclovir as reported in the relevant trials.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 2, 2005), MEDLINE (January 1966 to June 2005), and EMBASE (1988 to June 2005). The reference lists of all relevant articles were reviewed. The primary author of relevant studies and the pharmaceutical company that manufactures acyclovir were contacted.

SELECTION CRITERIA

Randomized controlled trials that evaluated otherwise healthy children zero to 18 years of age, with chickenpox.

DATA COLLECTION AND ANALYSIS

Two authors independently reviewed the studies for eligibility. Two authors independently assessed methodological quality of the relevant studies using the Jadad scale and allocation concealment. Differences were resolved by consensus. Data were extracted by one author using a structured form and checked by a second. Continuous data were converted to the weighted mean difference (WMD). Weighted mean differences were combined into an overall estimate using random effects. There were too few studies to consider exploring statistical heterogeneity between studies (i.e., differences in reported effects), formally, or to assess for publication bias.

MAIN RESULTS

Three studies were included. Study quality was three (n = 2) and four (n = 1) on the Jadad scale. Acyclovir was associated with a reduction in the number of days with fever (-1.1 days, 95% CI -1.3 to -0.9) and in reducing the maximum number of lesions (-76 lesions, -145 to -8). Results were less supportive with respect to the number of days to no new lesions and the number of days to the relief of itching. There were no clinically important differences between acyclovir and placebo with respect to complications associated with chickenpox or adverse effects associated with the treatment.

AUTHORS' CONCLUSIONS

Acyclovir appears to be effective in reducing the number of days with fever and the maximum number of lesions among otherwise healthy children with chickenpox. The results were less convincing with respect to the number of days to no new lesions and relief of itchiness. The clinical importance of acyclovir treatment in otherwise healthy children remains uncertain.

Human herpes viruses in pregnancy: cytomegalovirus, Epstein-Barr virus, and varicella zoster virus

Viruses of the human herpesvirus family can have profound effects on pregnancy. Primary maternal infection with cytomegalovirus (CMV) and varicella during pregnancy has been associated with fetal abnormalities and neonatal disease. Public awareness of the role of cytomegalovirus in the etiology of developmental disorders and chronic disabilities needs to increase. With time, we may see new interventions for treatment of infected pregnant women and prevention of long-term effects. Attention must be focused on development of a safe and effective vaccine. With the introduction of an efficacious varicella vaccine, the rate of varicella in pregnancy is expected to decrease dramatically. Physicians caring for women have the opportunity to prevent the complications of varicella by identifying and vaccinating susceptible women.

Acyclovir for treating varicella in otherwise healthy children and adolescents

BACKGROUND

Acyclovir has the potential to shorten the course of illness which may result in reduced costs and morbidity associated with chickenpox.

OBJECTIVES

1) To examine the evidence evaluating the efficacy of acyclovir in alleviating symptoms of chickenpox and shortening the duration of illness. 2) To examine complications of chickenpox and adverse effects associated with acyclovir as reported in the relevant trials.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1, 2003), MEDLINE (January 1966 to May 2003), and EMBASE (1988 to April 2003). The reference lists of all relevant articles were reviewed. The primary author of relevant studies and the pharmaceutical company that manufactures acyclovir were contacted.

SELECTION CRITERIA

Randomized controlled trials that evaluated otherwise healthy children zero to 18 years of age, with chickenpox.

DATA COLLECTION AND ANALYSIS

Two reviewers independently reviewed the studies for eligibility. Two reviewers independently assessed methodological quality of the relevant studies using the Jadad scale and allocation concealment. Differences were resolved by consensus. Data were extracted by one reviewer using a structured form and checked by a second.Continuous data were converted to the weighted mean difference (WMD). Weighted mean differences were combined into an overall estimate using random effects. There were too few studies to consider exploring statistical heterogeneity between studies (i.e., differences in reported effects), formally, or to assess for publication bias.

MAIN RESULTS

Three studies were included. Study quality was three (n = 2) and four (n = 1) on the Jadad scale. Acyclovir was associated with a reduction in the number of days with fever (-1.1 days, 95% CI -1.3 to -0.9) and in reducing the maximum number of lesions (-76 lesions, -145 to -8). Results were less supportive with respect to the number of days to no new lesions and the number of days to the relief of itching. There were no clinically important differences between acyclovir and placebo with respect to complications associated with chickenpox or adverse effects associated with the treatment.

REVIEWERS' CONCLUSIONS

Acyclovir appears to be effective in reducing the number of days with fever and the maximum number of lesions among otherwise healthy children with chickenpox. The results were less convincing with respect to the number of days to no new lesions and relief of itchiness. The clinical importance of acyclovir treatment in otherwise healthy children remains controversial.

Acyclovir for treating varicella in otherwise healthy children and adolescents: a systematic review of randomised controlled trials

BACKGROUND

Acyclovir has the potential to shorten the course of chickenpox which may result in reduced costs and morbidity. We conducted a systematic review of randomised controlled trials that evaluated acyclovir for the treatment of chickenpox in otherwise healthy children.

METHODS

MEDLINE, EMBASE, and the Cochrane Library were searched. The reference lists of relevant articles were examined and primary authors and Glaxo Wellcome were contacted to identify additional trials. Two reviewers independently screened studies for inclusion, assessed study quality using the Jadad scale and allocation concealment, and extracted data. Continuous data were converted to a weighted mean difference (WMD). Overall estimates were not calculated due to differences in the age groups studied.

RESULTS

Three studies were included. Methodological quality was 3 (n = 2) and 4 (n = 1) on the Jadad scale. Acyclovir was associated with a significant reduction in the number of days with fever, from -1.0 (95% CI -1.5,-0.5) to -1.3 (95% CI -2.0,-0.6). Results were inconsistent with respect to the number of days to no new lesions, the maximum number of lesions and relief of pruritus. There were no clinically important differences between acyclovir and placebo with respect to complications or adverse effects.

CONCLUSION

Acyclovir appears to be effective in reducing the number of days with fever among otherwise healthy children with chickenpox. The results were inconsistent with respect to the number of days to no new lesions, the maximum number of lesions and the relief of itchiness. The clinical importance of acyclovir treatment in otherwise healthy children remains controversial.

Antiviral prophylaxis and treatment in chickenpox. A review prepared for the UK Advisory Group on Chickenpox on behalf of the British Society for the Study of Infection

Prophylactic intervention with varicella-zoster immunoglobulin early in the incubation period can prevent or attenuate the disease manifestations of varicella in susceptible contacts at high risk from this infection. Detailed guidelines are issued in the UK Department of Health publication on Immunization against Infectious Disease. Sensitive immunoassays are available for investigation of antibody status and subclinical seroconversion. Live attenuated varicella vaccine, which has been used successfully post-exposure as well as electively elsewhere, is at present not generally available in the UK. Effective protocols for prophylaxis against varicella with the antiviral agent aciclovir are not yet established. The nucleoside analogue aciclovir (syn: acyclovir, Zovirax) is effective in inhibiting replication of VZV when given at a dosage higher than that required for treatment of HSV, and is currently the only available and approved treatment for varicella in the U.K. Intravenous aciclovir therapy for 5-10 days is effective for varicella in neonates and the immunocompromised, and for varicella pneumonia or other complications in adults and children, if begun early. Oral aciclovir is only effective if begun with 24 h of onset of rash. With that proviso. it is recommended for treatment of varicella in otherwise healthy adults and adolescents, but not for routine use in children under 13 years of age unless they are sibling contacts or have other medical conditions. Aciclovir has a high therapeutic index and good safety profile, but caution is advised with use in pregnancy.

Persistence of protective immunity after postexposure prophylaxis of varicella with oral aciclovir in the family setting

The persistence of protective immunity after postexposure prophylaxis against varicella using oral aciclovir was evaluated in the family setting. Sixty one of 78 recipients of oral aciclovir were assessed by questionnaire, and 13 of 61 were evaluated for serum antibody to varicella zoster virus (VZV) using the fluorescent antibody to membrane antigen method. The observation period ranged from 33 to 50 months. None of those (n = 44) who had initially seroconverted to VZV after aciclovir prophylaxis developed breakthrough varicella. All 13 who had serology repeated still had titres > or = 4. Antibody titres in those who had histories of re-exposure to the virus were significantly higher than in those who had not (p < 0.01).

Oral acyclovir prophylaxis of varicella after intimate contact

OBJECTIVES

Whether oral acyclovir (ACV) given in late incubation can prevent clinical varicella or not.

MATERIALS AND METHODS

Twenty-seven healthy infants and children susceptible to varicella received oral ACV (40 mg/kg daily in four divided doses) for 5 days, starting 9 or 11 days after exposure from the index case in the family (2 in the classroom). The clinical features were compared with 13 control children who did not receive ACV. Enzyme-linked immunoassay was used to detect varicella-zoster virus (VZV) antibody and, in follow-up immunologic studies, lymphocyte proliferative response was added. In some cases, blood culture and polymerase chain reaction with Southern hybridization were used for detection of viremia.

RESULTS

Among the 27 children in the treatment group, two (7.4%) developed the disease and seroconversion was observed in 17 subjects (63%). Follow-up immunologic studies in 12 of these 17 seroconverted subjects 30 months later showed persistent cellular and/or humoral immunity to VZV. Only one subject, bled 11 days after exposure, had positive VZV DNA and blood culture for VZV. On the other hand 10 of 13 (77%) control subjects developed clinical varicella.

CONCLUSIONS

Oral ACV administration to healthy susceptible subjects at the beginning of secondary viremia in the late incubation period (9 days after exposure) can effectively prevent or modify clinical varicella.

Control of varicella-zoster infection on renal and other specialist units

The introduction of chickenpox onto our renal unit recently raised several issues surrounding the management of patient and staff contracts. This paper describes the action taken and makes various recommendations for future management of similar cases. Guidelines are proposed for the management of patients and staff as well as the role of the infection control team in handling a chickenpox problem. Future developments, including the use of VZ vaccine for patient and staff, are also discussed.

Comparison of specific immunities to varicella-zoster virus following post-exposure prophylaxis of varicella by oral acyclovir observed in a family

An otherwise healthy 3-year-old girl developed severe varicella complicated by aseptic meningitis and received intravenous acyclovir (ACV) therapy. Her two siblings who were susceptible to varicella-zoster virus (VZV) and closely exposed to VZV in the family received oral ACV (45 or 54 mg/kg per day in four divided doses for 7 days) starting 8 days after onset of the index case for post-exposure prophylaxis of varicella. They showed only five or seven papules over the body without fever 12 days after onset of the index case, while they had one-third or half the level of antibody titer and equal sized skin reactions to VZV antigen of the index case 2.5 months later.