Varicella vaccination in children after bone marrow transplantation

An Immune Recovery-Based Revaccination Protocol for Pediatric Hematopoietic Stem Cell Transplant Recipients: Revaccination Outcomes Following Pediatric HSCT

Following hematopoietic stem cell transplant (HSCT), patients are at increased risk of vaccine-preventable diseases (VPDs) and experience worse outcomes of VPDs compared to immunocompetent patients. Therefore, patients are routinely vaccinated post-HSCT to restore VPD immunity. Published guidelines recommend revaccination based on time post-HSCT, although optimal revaccination timing and the value of using other clinical and laboratory variables to guide revaccination remain unclear. An institutional immune recovery-based protocol to guide timing of revaccination is used at Children's Hospital Colorado. This protocol incorporates time from transplant, time off immunosuppressive therapy and intravenous immunoglobulin replacement, absence of active graft-versus-host disease (GVHD), and minimum absolute CD4 count, absolute lymphocyte count (ALC), and immunoglobulin G (IgG) levels. The objective of this study is to evaluate the performance of this immune recovery-based revaccination protocol by determining rates of seroprotective vaccine responses achieved and describing demographic, clinical, and laboratory markers associated with protective antibody titers post-revaccination. Rates of seroprotection following revaccination were retrospectively determined for patients who received autologous or allogeneic HSCTs at Children's Hospital Colorado from 2007 to 2017. Percent seropositivity after revaccination was determined for ten VPDs: measles, mumps, rubella, varicella, tetanus, diphtheria, Haemophilus influenzae type B (Hib), poliovirus, hepatitis B virus (HBV), and Streptococcus pneumoniae. The impact of covariates, including post-HSCT vaccine timing, patient demographics, clinical features (diagnosis, donor and conditioning regimen data, GVHD, cytomegalovirus disease), and laboratory parameters (CD4 count, ALC, IgG level), on rates of seroprotection post-revaccination was determined using Wilcoxon rank sum, Fisher's exact, or chi-square tests, as appropriate. One hundred-twelve unique patients among 427 HSCT recipients had available data for both revaccination timing and vaccine titers. Among these, high rates of seroprotection were achieved after revaccination for rubella (100%), diphtheria (100%), tetanus (100%), and Hib (98%). More modest rates of seroprotection were achieved after revaccination with HBV (87%) and pneumococcal conjugate (85%) vaccines. Seroprotection was lower after revaccination with measles (76%), pneumococcal polysaccharide (72%), mumps (67%), and varicella (25%) vaccines. Greater rates of seroprotection were associated with younger age (hepatitis B vaccine, P = .04), lack of prior rituximab treatment (pneumococcal conjugate vaccine, P = .005), lack of total body irradiation (pneumococcal conjugate vaccine, P = .03), and receipt of a non-cord blood transplant (pneumococcal polysaccharide vaccine, P = .04). These results suggest that a revaccination protocol that incorporates both time post-HSCT and patient-specific indicators of immunologic recovery can achieve high rates of seroprotection against most VPDs. Seroprotection rates for HBV and PCV were notably among the highest reported in children post-HSCT, suggesting that an immune recovery-based protocol may improve seroprotection for some VPDs that frequently are associated with lower vaccine responses post-HSCT. Seroprotection rates for other VPDs remained suboptimal after revaccination. Therefore, evaluation of additional strategies, such as the use of novel markers of immune competence and new vaccines, to further optimize protection against VPDs in this population is warranted.

Late-onset visceral varicella-zoster virus infection presented as acute liver failure after allogeneic hematopoietic stem cell transplantation

Although much less common than localized zoster, initial presentation of varicella-zoster virus (VZV) as visceral infection can occur especially after allogeneic hematopoietic stem cell transplantation (HSCT). We herein report a case of post-transplant visceral VZV infection presenting as fatal acute liver failure. It developed 4 years after allogeneic HSCT when a long-term prophylactic anti-VZV agent administration was discontinued. VZV should be listed as a causative pathogen of acute liver failure even years after allogeneic HSCT. Indication for, and duration of anti-VZV prophylaxis should be further investigated.

Vaccine-preventable disease following allogeneic haematopoietic stem cell transplant in Western Australia

AIM

Infection is an important and frequent cause of mortality and morbidity following allogeneic haematopoietic stem cell transplantation (HSCT). This study was conducted to determine the epidemiology and clinical phenotype of vaccine-preventable disease in children who have undergone HSCT following the implementation of a standard revaccination programme.

METHODS

Children receiving first allogeneic HSCT in Western Australia between January 2005 and December 2014 were eligible for recruitment. Patients received standard antimicrobial prophylaxis and were vaccinated according to the West Australian post-HSCT immunisation schedule, commencing 6 months following HSCT. Children who developed any illness post-HSCT were reviewed, and investigations for infectious disease were undertaken as clinically indicated. Positive identification of vaccine-preventable disease was documented with the clinical course of the illness.

RESULTS

A total of 71 patients were enrolled in the study. The overall incidence of vaccine-preventable disease following HSCT was 19.7%; influenza accounted for 50% of all cases, herpes zoster for 42.9%. All episodes occurred late, beyond day 100 post-HSCT. Overall survival for matched-sibling donor transplants was 83.3 and 75.0% at 1 and 5 years, respectively, and was 72.3 and 63.3% for alternative donor transplants. Mortality due to vaccine-preventable disease was low, with one death from disseminated herpes zoster.

CONCLUSIONS

There is a high incidence of vaccine-preventable morbidity post-allogeneic HSCT in West Australian children. Viral aetiology constitutes the main burden, namely, influenza infection and varicella zoster virus reactivation. Further efforts are required to identify the most appropriate preventative strategies.

Vaccination of haemopoietic stem cell transplant recipients: guidelines of the 2017 European Conference on Infections in Leukaemia (ECIL 7)

Infection is a main concern after haemopoietic stem cell transplantation (HSCT) and a major cause of transplant-related mortality. Some of these infections are preventable by vaccination. Most HSCT recipients lose their immunity to various pathogens as soon as the first months after transplant, irrespective of the pre-transplant donor or recipient vaccinations. Vaccination with inactivated vaccines is safe after transplantation and is an effective way to reinstate protection from various pathogens (eg, influenza virus and Streptococcus pneumoniae), especially for pathogens whose risk of infection is increased by the transplant procedure. The response to vaccines in patients with transplants is usually lower than that in healthy individuals of the same age during the first months or years after transplant, but it improves over time to become close to normal 2-3 years after the procedure. However, because immunogenic vaccines have been found to induce a response in a substantial proportion of the patients as early as 3 months after transplant, we recommend to start crucial vaccinations with inactivated vaccines from 3 months after transplant, irrespectively of whether the patient has or has not developed graft-versus-host disease (GvHD) or received immunosuppressants. Patients with GvHD have higher risk of infection and are likely to benefit from vaccination. Another challenge is to provide HSCT recipients the same level of vaccine protection as healthy individuals of the same age in a given country. The use of live attenuated vaccines should be limited to specific situations because of the risk of vaccine-induced disease.

Vaccines in pediatric transplant recipients-Past, present, and future

Infections significantly impact outcomes for solid organ and hematopoietic stem cell transplantation in children. Vaccine-preventable diseases contribute to morbidity and mortality in both early and late posttransplant time periods. Several infectious diseases and transplantation societies have published recommendations and guidelines that address immunization in adult and pediatric transplant recipients. In many cases, pediatric-specific studies are limited in size or quality, leading to recommendations being based on adult data or mixed adult-pediatric studies. We therefore review the current state of evidence for selected immunizations in pediatric transplant recipients and highlight areas for future investigation. Specific attention is given to studies that enrolled only children.

Adherence and immune response to revaccination following hematopoietic stem cell transplantation at a pediatric onco-hematology reference center

BACKGROUND

Revaccination after hematopoietic stem cell transplantation (HSCT) is necessary to compensate for the loss of immunological memory. The aims of this study were to evaluate the adherence to revaccination schedule and the humoral immune response to different vaccine antigens in HSCT pediatric and young adult patients.

METHODS

Patients submitted to HSCT for over 3 years were recruited. After written informed consent, a questionnaire was filled in, the vaccination card was analyzed, a blood sample was collected and tested by ELISA for diphtheria, Haemophilus influenzae type b (Hib), hepatitis A, hepatitis B, tetanus, measles, rubella, and varicella antibodies.

RESULTS

Sixty-three patients (mean age at HSCT, 10.7 years) were evaluated. Forty-one (65%) were male; 34 (54%) had allogeneic and 29 (46%), autologous HSCT. Complete adherence to diphtheria revaccination was found in 79.4% patients and seropositivity was found in 92% of those who completed the revaccination schedule; for Hib, 68.3% adherence and 95.3% seropositivity were observed; for hepatitis A, 63.5% adherence and 92.5% seropositivity; for 3 doses of hepatitis B, 86.8% adherence and 79.2% seropositivity; for tetanus, 79.4% adherence and 100% seropositivity; for measles and rubella, 17.5% adherence and 100% seropositivity; for varicella, 7.9% adherence and 100% seropositivity. The existence of a Vaccination Center for Special Immunobiologicals in patients' municipality was positively associated with completed vaccine schedule; on the other hand, chronic GVHD was negatively associated with revaccination adherence.

CONCLUSION

Hematopoietic stem cell transplantation patients showed good seropositivity rates after complete vaccination schedule. However, a low coverage rate was observed for live attenuated antigens.

Vaccinations in immunosuppressive-dependent pediatric inflammatory bowel disease

AIM

To determine the vaccination rates in pediatric immunosuppression-dependent inflammatory bowel disease (IBD) and review the safety and efficacy of vaccinations in this population.

METHODS

The electronic medical records from October 2009 to December 2015 of patients diagnosed with IBD at 10 years of age or younger and prescribed anti-tumor necrosis factor alpha (anti-TNF-α) therapy were reviewed for clinical history, medication history, vaccination history, and hepatitis B and varicella titers. Literature discussing vaccination response in IBD patients were identified through search of the MEDLINE database and reviewed using the key words “inflammatory bowel disease”, “immunization”, “vaccination”, “pneumococcal”, “varicella”, and “hepatitis B”. Non-human and non-English language studies were excluded. Search results were reviewed by authors to select articles that addressed safety and efficacy of immunizations in inflammatory bowel disease.

RESULTS

A total of 51 patients diagnosed with IBD prior to the age of 10 and receiving anti-TNF-α therapy were identified. Thirty-three percent of patients (17/51) had incomplete or no documentation of vaccinations. Sixteen case reports, cohort studies, cross-sectional studies, and randomized trials were determined through review of the literature to describe the safety and efficacy of hepatitis B, pneumococcal, and varicella immunizations in adult and pediatric patients with IBD. These studies showed that patients safely tolerated the vaccines without significant adverse effects. Importantly, IBD patients receiving immunosuppressive medications, particularly anti-TNF-α treatment, have decreased vaccine response compared to controls. However, the majority of patients are still able to achieve protective levels of specific antibodies.

CONCLUSION

Immunizations have been shown to be well-tolerated and protective immunity can be achieved in patients with IBD requiring immunosuppressive therapy.

Studies with herpes zoster vaccines in immune compromised patients

INTRODUCTION

The active component of the herpes zoster vaccine (ZVL), licensed for people ≥50 years of age, is a live attenuated varicella-zoster virus. ZVL is contraindicated for immune compromised individuals, with limited regard to the degree of immunosuppression. Areas covered: This review evaluates phase I and II and observational studies for ZVL, and published reports of the off-label use of ZVL, for conditions and therapies for which investigators considered the risk-benefit for using ZVL to be favorable. It also discusses exploratory trials of ZVL for additional immune compromising conditions, and summarizes clinical guidelines from many countries and professional societies that are based upon recent investigations. Studies in immune compromised patients of investigational vaccines that do not contain live virus are reviewed. Expert commentary: It is likely that past and ongoing research with ZVL will define immune compromising diseases and/or therapies for which the risk-benefit for using ZVL vaccine is favorable. The main variables to consider in this assessment in immune compromised patients are safety, immunogenicity, protection against herpes zoster, and persistence of protection. Vaccination against herpes zoster prior to suppressing immunity is an important clinical strategy, although efficacy of this approach has not been evaluated in a clinical trial.

The Successful Treatment of a Cord Blood Transplant Recipient with Varicella Zoster Virus Meningitis, Radiculitis and Myelitis with Foscarnet

Infections of the central nervous system (CNS) with varicella zoster virus (VZV) is a rare occurrence after allogeneic hematopoietic stem cell transplantation. We herein report a case of VZV meningitis, radiculitis and myelitis that developed 8 months after cord blood transplantation, shortly after the cessation of cyclosporine and low-dose acyclovir. Although treatment with acyclovir did not achieve a satisfactory response, the patient was successfully treated with foscarnet. Our report indicates that VZV infection should be considered in allo-hematopoietic stem cell transplantation (HSCT) patients with CNS symptoms and that foscarnet may be effective for the treatment of acyclovir-resistant VZV infections of the CNS. The development of optimal prophylactic strategies and vaccination schedules may eradicate post-transplant VZV disease.

Zoster prophylaxis after allogeneic hematopoietic cell transplantation using acyclovir/valacyclovir followed by vaccination

Varicella zoster virus (VZV) disease (usually cutaneous zoster) occurs frequently after hematopoietic cell transplantation (HCT), and postherpetic neuralgia (PHN) results in poor quality of life. The optimal prophylaxis of VZV disease/PHN has not been established. At our center, before 2008, VZV prophylaxis consisted of ∼1 year of post-HCT acyclovir/valacyclovir ("old strategy"), whereas post-2008 prophylaxis consisted of 2 years of acyclovir/valacyclovir followed by immunization using varicella vaccine ("new strategy"). We performed a retrospective study comparing the cumulative incidence of VZV disease and PHN among patients who completed the old strategy (n = 153) vs the new strategy (n = 125). Patients who completed the old strategy had a significantly higher cumulative incidence of VZV disease (33% vs 17% at 5 years, P ≤ .01) and PHN (8% vs 0% at 5 years, P = .02). In conclusion, VZV prophylaxis with 2 years of acyclovir/valacyclovir followed by vaccination appears to result in a low incidence of VZV disease and may eliminate PHN.

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.

Autoimmune disease and vaccination: impact on infectious disease prevention and a look at future applications

Vaccines hold promise both for the prevention of infections and as potential immunologic therapy for patients with autoimmune disease (AD). These patients are at high risk for both common and opportunistic infections, but this risk can be significantly reduced and even obviated with the use of recommended available vaccines. Unfortunately, patients with ADs are not routinely offered or provided indicated vaccinations and have higher rates of complications from vaccine-preventable illnesses than patients without ADs. In addition, vaccine therapy is currently under study for the treatment of autoimmune disorders, with early studies demonstrating immunomodulatory effects that may counter undesired immune activation and alleviate disease activity.

Live virus vaccines in transplantation: friend or foe?

Solid organ and hematopoietic stem cell transplant recipients may be exposed to diseases which may be prevented through live attenuated virus vaccines (LAVV). Because of their immunosuppression, these diseases can lead to severe complications in transplant recipients. Despite increasing evidence regarding the safety and effectiveness of certain LAVV, these vaccines are still contraindicated for immunocompromised patients, such as transplant recipients. We review the available studies on LAVV, such as varicella zoster, measles-mumps-rubella, influenza, yellow fever, polio, and Japanese encephalitis vaccines in transplant patients. We discuss the current recommendations and the potential risks, as well as the expected benefits of LAVV immunization in this population.

Conjugation of a brain-penetrant peptide with neurotensin provides antinociceptive properties

Neurotensin (NT) has emerged as an important modulator of nociceptive transmission and exerts its biological effects through interactions with 2 distinct GPCRs, NTS1 and NTS2. NT provides strong analgesia when administered directly into the brain; however, the blood-brain barrier (BBB) is a major obstacle for effective delivery of potential analgesics to the brain. To overcome this challenge, we synthesized chemical conjugates that are transported across the BBB via receptor-mediated transcytosis using the brain-penetrant peptide Angiopep-2 (An2), which targets LDL receptor-related protein-1 (LRP1). Using in situ brain perfusion in mice, we found that the compound ANG2002, a conjugate of An2 and NT, was transported at least 10 times more efficiently across the BBB than native NT. In vitro, ANG2002 bound NTS1 and NTS2 receptors and maintained NT-associated biological activity. In rats, i.v. ANG2002 induced a dose-dependent analgesia in the formalin model of persistent pain. At a dose of 0.05 mg/kg, ANG2002 effectively reversed pain behaviors induced by the development of neuropathic and bone cancer pain in animal models. The analgesic properties of ANG2002 demonstrated in this study suggest that this compound is effective for clinical management of persistent and chronic pain and establish the benefits of this technology for the development of neurotherapeutics.

2013 IDSA clinical practice guideline for vaccination of the immunocompromised host

An international panel of experts prepared an evidenced-based guideline for vaccination of immunocompromised adults and children. These guidelines are intended for use by primary care and subspecialty providers who care for immunocompromised patients. Evidence was often limited. Areas that warrant future investigation are highlighted.

Vaccination of immunocompromised patients

Vaccination of immunocompromised patients is challenging both regarding efficacy and safety. True efficacy data are lacking so existing recommendations are based on immune responses and safety data. Inactivated vaccines can generally be used without risk but the patients who are most at risk for infectious morbidity and mortality as a result of their severely immunosuppressed state are also those least likely to respond to vaccination. However, vaccination against pneumococci, Haemophilus influenzae and influenza are generally recommended. Live vaccines must be used with care because the risk for vaccine-associated disease exists.

Clinical practice implications of immunizations after pediatric bone marrow transplant: a literature review

The number of pediatric bone marrow transplants is increasing for malignant and nonmalignant diseases. The number of survivors is also increasing, and their long-term health and protection from infection is increasingly important. To prevent infections, it is standard practice to re-immunize pediatric patients after bone marrow transplant (BMT) using the Centers for Disease Control and Prevention immunization guidelines; however, surveys in the United States and other parts of the world indicate that many BMT patients do not receive all the recommended immunizations. A literature review was conducted to identify research based on evidence for immunization following BMT and to recognize barriers to the process. Also, the immunization clinical guidelines from 2000 and 2011 for patients following BMT were compared and an updated clinical protocol and immunization schedule was developed to reflect the current evidence, encourage a change in practice, and discourage fragmented care.

Dynamics in children and adolescents who experience varicella zoster virus infections after haematopoietic stem cell transplantation: a case-control study

We evaluated the incidence of varicella-zoster virus (VZV) infections, including herpes zoster (HZ), and investigated the associated risk factors for HZ and compared lymphocyte subsets of these patients at 1, 3 and 6 months following haematopoietic stem cell transplantation (HSCT) in a case-control study in children and adolescents. The incidence of HZ infection at the first year after HSCT was 17/125 (13·6%). The cumulative incidence of HZ infection was 22/125 (17·6%). Sixteen (73%) cases with HZ and 11 (32%) cases in the control group had a diagnosis of malignant disorder. No significant difference was noted between the HZ group and the control group in absolute lymphocyte number and subsets (except WBC) at the pre-transplant evaluation. Pre-transplant WBC count was statistically lower in the HZ group (P<0·05). The CD4/CD8 ratios were lower in the HZ group during the first 6 months after HSCT, and the decrease was statistically significant at 6 months compared to the control group. In conclusion, patients undergoing HSCT for a malignant disorder had a significantly higher risk of VZV infection than those with non-malignant disorders and pretransplant donor characteristics were not helpful in predicting risk of post-transplant VZV infection.

NCI, NHLBI/PBMTC first international conference on late effects after pediatric hematopoietic cell transplantation: persistent immune deficiency in pediatric transplant survivors

Defective immune reconstitution is a major barrier to successful hematopoietic cell transplantation (HCT), and has important implications in the pediatric population. There are many factors that affect immune recovery, including stem cell source and graft-versus-host disease (GVHD). Complete assessment of immune recovery, including T and B lymphocyte evaluation, innate immunity, and response to neoantigens, may provide insight as to infection risk and optimal time for immunizations. The increasing use of cord blood grafts requires additional study regarding early reconstitution and impact upon survival. Immunization schedules may require modification based upon stem cell source and immune reconstitution, and this is of particular importance as many children have been incompletely immunized, or not at all, before school entry. Additional studies are needed in children post-HCT to evaluate the impact of differing stem cell sources upon immune reconstitution, infectious risks, and immunization responses.

The epidemiology of herpes zoster in 226 children with acute lymphoblastic leukemia

BACKGROUND

Herpes zoster (HZ) is rare in healthy children, but may occur frequently and take a complicated course in children receiving chemotherapy. We determined the morbidity related to HZ in children with acute lymphoblastic leukaemia (ALL).

PROCEDURE

Medical records of 226 children diagnosed with ALL were reviewed. Of these, 160 were seropositive at the time of diagnosis. HZ eruptions during primary chemotherapy, during therapy for relapse and following bone marrow transplantation (BMT) were registered.

RESULTS

A total of 90 eruptions were recorded: 63 first-time attacks and 27 recurrent episodes among 14 children. All eruptions were treated with acyclovir (ACV) and in 60% it was given intravenously. Cutaneous dissemination occurred in 11 cases, post herpetic neuralgia in five, visceral dissemination in none. During primary chemotherapy 47 children (29%) had HZ. The eruption rate was significantly higher in children on high risk protocols compared to children on standard/intermediate risk protocols (0.36 vs. 0.07/0.09 per year) and was related to intensity of chemotherapy. During therapy for relapse 7 of 29 (24%) had a total of 13 eruptions. Following BMT 9 of 26 (35%) had a total of 10 eruptions.

CONCLUSION

Almost one third of the seropositive children had HZ during primary chemotherapy. Of those treated on high risk protocols more than half had one or more eruptions during the course of treatment. The risk of complicated HZ is small, but prolonged intensive chemotherapy can lead to considerable morbidity from repeated eruptions. Attempts to improve immunity by vaccination after attaining remission seem warranted.

Safety and immunogenicity of the live attenuated varicella vaccine following T replete or T cell-depleted related and unrelated allogeneic hematopoietic cell transplantation (alloHCT)

There are limited studies assessing the live attenuated varicella vaccine following allogeneic hematopoietic cell transplantation (alloHCT). Because of the morbidity of varicella acquired after childhood, we immunized and retrospectively analyzed the safety and immunogenicity of this vaccine in 46 varicella zoster virus (VZV) seronegative patients <20 years old at HCT who achieved a CD4 cell count ≥200/μL, were off immunosuppression, and responded to ≥1 post-HCT vaccines. Two vaccinated patients lacking follow-up titers were excluded from analysis. Stem cells were derived from an HLA-matched sibling (n = 18) or an alternative (HLA mismatched related or unrelated) donor (n = 26). Median time to vaccination was 4 years. Sixty-four percent of patients seroconverted following 1 immunization. There was no significant difference in response between recipients of a matched related or alternative donor graft (P = .2) or between those given a T cell-depleted or T-replete alternative donor graft (P = .27). Three of 44 patients developed a self-limited varicella-like rash within 2.5 weeks of immunization. With a median follow-up of 29.1 (range: 6.9-167.1) months, there were no subsequent cases of varicella-like rashes. No patient developed shingles. This study suggests that this vaccine is safe and immunogenic when given according to preset clinical and immunologic milestones, warranting larger prospective studies in patients ≥24 months following HCT as outlined in current post-HCT vaccine guidelines.

Immunization of hematopoietic stem cell transplant recipients against vaccine-preventable diseases

Worldwide, over 40,000 hematopoietic cell transplants (HCT) are carried out each year, with the majority of patients surviving long term. Owing to their new immune systems, these patients are susceptible to a variety of preventable infectious diseases. The 2009 influenza pandemic, the increase in pertussis and antibiotic-resistant pneumococcus, as well as recent outbreaks of measles and mumps in immunocompetent individuals further highlight the need for effective revaccination of HCT recipients. Post-transplant vaccine guidelines, including those published in 2009, recommend immunization of all patient groups at fixed times post-HCT. Although early vaccination to protect against vaccine-preventable diseases is desirable, there are still limited data on whether this approach is efficacious in patient groups whose immune recovery differs from recipients of an unmodified HLA-matched sibling transplant. In the absence of such data, prospective trials are needed to better define the optimal timing for immunizing recipients of alternative donors. Ideally, such trials should be designed to identify biological markers that will predict an optimal and durable vaccine response.

Herpes viruses in transplant recipients: HSV, VZV, human herpes viruses, and EBV

The herpes viruses are responsible for a wide range of diseases in patients following transplant, resulting from direct viral effects and indirect effects, including tumor promotion. Effective treatments and prophylaxis exist for the neurotropic herpes viruses HSV-1, HSV-2, varicella zoster virus, and possibly HHV-6. Antivirals seem to be less effective at prevention of the tumor-promoting effects of Epstein-Barr virus and HHV-8. Reduction in immunosuppression is the cornerstone to treatment of many diseases associated with herpes virus infections.

Post-hematopoietic stem cell transplant immunization practices in the Pediatric Blood and Marrow Transplant Consortium

BACKGROUND

A survey of National Marrow Donor Program transplant centers in 1995 demonstrated a wide range of immunization practices in post-hematopoietic stem cell transplant (HSCT) recipients, which led to the 2000 Centers for Disease Control and Prevention (CDC) recommendations for vaccination after HSCT. We surveyed the principal investigators of the Pediatric Blood and Marrow Transplant Consortium (PBMTC) to identify immunization practice patterns after HSCT and assess compliance with the 2000 CDC guidelines.

PROCEDURE

Approval was obtained from the Medical University of South Carolina Institutional Review Board. A 33 question survey using surveymonkey.com was distributed by email to principal investigators in the PBMTC.

RESULTS

Forty-one (40%) of the 102 pediatric HSCT centers participating in the PBMTC responded. Thirty of the responding centers completed the entire survey. For individual vaccines, compliance with the CDC guidelines ranged from 22% to 93%. Less than 20% of the centers reported schedules consistent with the 2000 CDC recommendations for both allogeneic and autologous HSCT recipients.

CONCLUSION

Despite the 2000 CDC guidelines, wide variation in post-HSCT immunization practices still exists. Updated guidelines have been needed, particularly to address the use of the pneumococcal conjugate vaccine. In conjunction with multiple other groups, the CDC recently released new immunization guidelines in October 2009. Additional data are still needed to adequately address the utility of incorporating immunologic parameters with the timing of vaccination after HSCT.

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.

Varicella vaccination of immunocompromised children

BACKGROUND

Exposure of immunocompromised children to varicella often requires postexposure prophylaxis. Exposures requiring this management are often not recognized. Varicella can be a severe disease when it occurs in immunocompromised children, in spite of antiviral therapy. Varicella exposure and varicella in these children can also disrupt scheduled therapy for their underlying illness. Both postexposure prophylaxis and treatment of varicella are likely to be expensive and use significant medical resources. Numerous trials have been undertaken to vaccinate children who are immunocompromised by a variety of conditions and therapies that depress their immune function.

METHODS

Clinical trials of varicella vaccine administration to immunocompromised children that were reported since 1975 were identified in the Ovid medical database. Reports were selected for analysis and discussion on the basis of their completeness and the utility of their conclusions.

RESULTS

Vaccination before immune compromise is discussed as a strategy for some settings. The obstacles, potential opportunities, and success in varicella vaccination for immunocompromised children are separately analyzed for (1) children with leukemia and other malignancies, (2) human immunodeficiency virus-infected children, and (3) children with hematopoietic stem cell or solid-organ transplantation.

CONCLUSIONS

Vaccination before immune compromise is often successful, and the vaccine-induced response is usually partially or fully protective. In many treatment settings, it is possible to safely vaccinate once the level of immune suppression has been reduced. Targets for future research are outlined. A consensus conference should be undertaken to develop guidelines for the use of varicella vaccine in immunocompromised children.

Reimmunization after hematopoietic stem cell transplantation

Hematopoietic stem cell transplant recipients lose immune memory of exposure to infectious agents and vaccines accumulated through a lifetime, and therefore need to be revaccinated. Reimmunization protocols vary greatly among hematopoietic stem cell transplant centers. Diphtheria and tetanus toxoids, pertussis vaccine, Haemophilus influenza type B conjugate, 23-valent pneumococcal polysaccharide, inactivated influenza and polio vaccine and live attenuated measles-mumps-rubella vaccine are the currently recommended vaccines to be included in a vaccination program after hematopoietic stem cell transplant. Other variables, such as stem cell source, new adjuvants, T-cell depleted transplants, nonmyeloablative conditioning and donor immunization have recently been introduced and a constant update of current recommendations are needed. Studies recently published, the use of other vaccines and the perspectives for different vaccination protocols are discussed in this review.

Herpes zoster infection in the post-hematopoietic stem cell transplant pediatric population may be preceded by transaminitis: an institutional experience

Herpes zoster (HZ), a varicella-zoster virus reactivation, frequently complicates hematopoietic stem cell transplantation (HSCT). Its incidence, complications, and associated risk factors in 310 children undergoing HSCT were reviewed. In all, 61 of 201(32%) patients who had undergone allogeneic and 10 of 109 (9%) patients who had undergone autologous HSCT developed HZ. Of 90 VZV seropositive allogeneic patients, 50 (53%) developed HZ. Seven (17%) of 41 VZV seropositive autologous patients developed HZ. Although a substantial number of patients develop HZ in the early post-HSCT period, risk for HZ persists and HZ can occur up to 5 years post-HSCT. Risk factors for HZ included age >10 years (P<0.0001), allogeneic HSCT (P<0.001), and total body irradiation (TBI) (P<0.059) in allogeneic recipients. Of 37, 22 (59%) patients experienced an elevated alanine aminotransferase (ALT), unassociated with GVHD, in the month preceding HZ. Of the 48/64 patients (75%) hospitalized for treatment (median stay, 6 days; range, 2-39), length of stay was unaffected by donor type but increased by cutaneous dissemination and visceral involvement (P=0.023 and 0.034, respectively) in allogeneic patients. Consideration of HZ infection particularly in patients >10 years of age with elevated ALT after TBI-conditioned allogeneic HSCT may permit earlier diagnosis and therapeutic intervention.

[Immunisation against varicella]

Two vaccines against varicella are now being licensed in France, both deriving from the Oka strain. Seroconversion has been obtained in almost 100% of the cases after one dose in toddlers and children, and two doses in adolescents and adults. Efficacy has been mainly established from the US experience, where a universal immunisation programme of children aged > 12 months with a catch-up for susceptible adolescents and adults was begun in 1995. The incidence of varicella has decreased by about 85% over all age groups. The safety of the vaccine is good, and most adverse events are represented by fever, reactions at the injection site and varicella-like rashes. For the time being, France has adopted restrictive recommendations for the use of this vaccine because of uncertainties with respect to the duration of protection, a shift of the disease towards older age and the potential increase of the incidence of herpes-zoster.