The controversy of varicella vaccination in children with acute lymphoblastic leukemia

Lymphocyte counts predict optimal timing of chemotherapy reinitiation after antivirus treatment for herpes zoster in children with leukemia

Herpes zoster (HZ) is rare in healthy children, but more prevalent in those with leukemia. Optimal timing of chemotherapy reinitiation after HZ treatment is challenging because chemotherapy suppresses immunity and increases risk of HZ relapse. We aimed to optimize the timing of chemotherapy reinitiation after HZ therapy in children with leukemia. The study included 31 children with acute leukemia and HZ infection. General information, clinical symptoms, laboratory test results, duration of HZ treatment, and prognosis were compared with those of children with leukemia alone. Correlation analysis was performed for 20 children who restarted chemotherapy after HZ treatment. Of 31 children with leukemia and HZ, 67.74% had lesions at multiple sites. The median time from chemotherapy initiation to HZ onset was 14.1 (1.5-29.5) months. Among 27 children included in the follow-up, there was one case of HZ relapse. After excluding children who did not continue chemotherapy after HZ treatment, the median interval between completion of HZ therapy and chemotherapy reinitiation in the remaining 20 children was 8.00 (- 3 to 27) days. Lymphocyte counts (LY#) on restarting chemotherapy correlated inversely with HZ lesion healing time (p < 0.05). LY# at the time of HZ onset were lower than those pre- and post-onset, and lower than those in the control group (p < 0.05). In conclusion, children with leukemia have a good HZ prognosis, but an increased risk of HZ recurrence. LY# at the time of chemotherapy reinitiation may be a useful indicator for selecting the optimal interval between antiviral therapy completion and chemotherapy reinitiation.

A prospective multicenter study on varicella-zoster virus infection in children with acute lymphoblastic leukemia

BACKGROUND AND METHODS

The study evaluated prognostic factors associated with varicella-zoster virus (VZV) infection and mortality in children with acute lymphoblastic leukemia (ALL) using data from the multicenter Chinese Children's Cancer Group ALL-2015 trial.

RESULTS

In total, 7,640 patients were recruited, and 138 cases of VZV infection were identified. The incidence of VZV infection was higher in patients aged ≥ 10 years (22.5%) and in patients with the E2A/PBX1 fusion gene (11.6%) compared to those aged < 10 years (13.25%, P = 0.003) or with other fusion genes (4.9%, P = 0.001). Of the 10 deaths in children with ALL and VZV infection, 4 resulted from VZV complications. The differences between groups in the 5-year overall survival, event-free survival, cumulative recurrence, and death in remission were not statistically significant. The proportion of complex infection was higher in children with a history of exposure to someone with VZV infection (17.9% vs. 3.6%, P = 0.022).

CONCLUSION

VZV exposure was associated with an increased incidence of complex VZV infection and contributed to VZV-associated death in children with ALL.

[Practical management during maintenance therapy of pediatric acute lymphoblastic leukemia: Recommendations of the French Society for Childhood and Adolescent Cancer and Leukemia (SFCE)]

Maintenance therapy is the last phase of treatment for acute lymphoblastic leukemia in children and adolescents. Although maintenance therapy is associated with toxicities and specific management issues, it is an essential phase of treatment that reduces the risk of relapse. The objective of this work is to propose a guide for the initiation, administration, and monitoring of maintenance therapy, and for the management of food, schooling, leisure, community life, risk of infection and links with family medicine.

Varicella post-exposure management for pediatric oncology patients

INTRODUCTION

The objective was to evaluate health care providers' (HCP) adherence to and efficacy of varicella post-exposure prophylaxis (PEP) recommendations. It was an observational, prospective, multicenter study set in Ile-de-France, France.

METHODS

All children under 18 with a cancer diagnosis, currently or within 3months of receiving cancer treatment, regardless of varicella zoster virus (VZV) serostatus or previous personal history of varicella, were eligible. Study participants with significant exposure were reviewed prospectively for PEP indications. Main outcome measures were the percentage of exposure situations for which HCP were guideline-compliant, the proportion of available VZV serostatuses and the incidence of breakthrough varicella after different PEP approaches.

RESULTS

A total of 51 patients from 15 centers were enrolled after 52 exposure episodes. Median age at exposure was 5 years (range, 1-15). Exposure within the household led to 38% of episodes. Prophylactic treatment consisted in specific anti-VZV immunoglobulins (V-ZIG) (n=19) or in oral aciclovir (n=15). No prophylactic treatment was given for 18 patients (in compliance, n=16). In compliance with guidelines, 17 patients received V-ZIG, 11 did not develop varicella (65%, [95% CI, 39-90%]); 15 received aciclovir, 13 did not develop varicella (87%, [95% CI, 67-100%]). Breakthrough varicella occurred in 11 patients, with simple clinical course in all cases; in 8/47 (17%) episodes when PEP was guideline-compliant versus 3/5 (60%) when not.

DISCUSSION

Recommendations have been respected and are efficient. PEP needs to be standardized and a study carried out to define the optimal approach. Anti-VZV immunization of seronegative family members should be encouraged.

Different Clinical Presentations and Outcomes of Disseminated Varicella in Children With Primary and Acquired Immunodeficiencies

Primary infection with varicella-zoster virus (VZV) causes chickenpox, a benign and self-limited disease in healthy children. In patients with primary or acquired immunodeficiencies, primary infection can be life-threatening, due to rapid dissemination of the virus to various organs [lung, gastrointestinal tract, liver, eye, central nervous system (CNS)]. We retrospectively described and compared the clinical presentations and outcomes of disseminated varicella infection (DV) in patients with acquired (AID) (n= 7) and primary (PID) (n= 12) immunodeficiencies. Patients with AID were on immunosuppression (mostly steroids) for nephrotic syndrome, solid organ transplantation or the treatment of hemopathies, whereas those with PID had combined immunodeficiency (CID) or severe CID (SCID). The course of the disease was severe and fulminant in patients with AID, with multiple organ failure, no rash or a delayed rash, whereas patients with CID and SICD presented typical signs of chickenpox, including a rash, with dissemination to other organs, including the lungs and CNS. In the PID group, antiviral treatment was prolonged until immune reconstitution after bone marrow transplantation, which was performed in 10/12 patients. Four patients died, and three experienced neurological sequelae. SCID patients had the worst outcome. Our findings highlight substantial differences in the clinical presentation and course of DV between children with AID and PID, suggesting differences in pathophysiology. Prevention, early diagnosis and treatment are required to improve outcome.

Varicella-zoster virus infection in the pediatric population with acute lymphoblastic leukemia in Poland

Varicella-zoster virus (VZV) infection in pediatric hemato-oncology patients can be a therapeutic problem when children are exposed to immunosuppression. The aim of this study is to evaluate the incidence of VZV infection, antiviral therapy and outcome in children with ALL treated in polish hemato-oncological centers between 2012 and 2019 years. This study included medical records of 1874 patients, aged 1 to 18 years, with newly diagnosed acute lymphoblastic leukemia. During chemotherapy, 406 children out of 1874 (21.6%) experienced viral infections. The incidence of VZV infection in the whole group children with ALL was 1.8%. Among them, 34 (8.4%) patients were diagnosed with VZV infection. Thirty-five episodes of viral infections were identified. The median time of VCV therapy was 12 days. Herpes zoster infection occurred in 24 (70.6%) children, and varicella in 10 (29.4%) ones. The average time from the start of chemotherapy to the appearance of herpes zoster was 7.26 ± 4.05 months. VZV infection occurred mainly during the maintenance therapy, the reinduction and induction phases. There was no correlation between steroid dosage or type and subsequent zoster. The total lymphocyte count of these patients on the first day of zoster was reduced. No serious complications were observed due to this infection. All patients survived. In conclusion, a low incidence of VZV infection was observed among pediatric patients with ALL in Poland. This analysis indicates that currently used therapeutic methods are effective in children with cancer and VZV infection. The main focus should be on the prevention of delayed chemotherapy.

Systemic viral infection in children receiving chemotherapy for acute leukemia

Systemic viral diseases frequently occur in allogeneic hematopoietic stem cell transplantation, but data in children receiving chemotherapy for acute leukemia are scarce. We therefore collected and analyzed the published data on symptomatic infection from cytomegalovirus, herpes simplex virus, varicella zoster virus, parvovirus B19, or adenovirus in pediatric acute leukemia. Reports on 68 children were identified, of whom 16 patients have died from the infection. Further studies have to (1) evaluate the true incidence of these infections in pediatric acute leukemia, (2) their impact on outcome, and (3) whether a subpopulation of patients could benefit from screening and prophylactic strategies.

Vaccination of patients with haematological malignancies who did not have transplantations: guidelines from the 2017 European Conference on Infections in Leukaemia (ECIL 7)

Patients with haematological malignancies are at high risk of infection because of various mechanisms of humoral and cell-mediated immune deficiencies, which mainly depend on underlying disease and specific therapies. Some of these infections are vaccine preventable. However, these malignancies are different from each other, and the treatment approaches are diverse and rapidly evolving, so it is difficult to have a common programme for vaccination in a haematology ward. Additionally, because of insufficient training about the topic, vaccination is an area often neglected by haematologists, and influenced by cultural differences, even among health-care workers, in compliance to vaccines. Several issues are encountered when addressing vaccination in haematology: the small size of the cohorts that makes it difficult to show the clinical benefits of vaccination, the subsequent need to rely on biological parameters, their clinical pertinence not being established in immunocompromised patients, scarcity of clarity on the optimal timing of vaccination in complex treatment schedules, and the scarcity of data on long-term protection in patients receiving treatments. Moreover, the risk of vaccine-induced disease with live-attenuated vaccines strongly limits their use. Here we summarise guidelines for patients without transplantations, and address the issue by the haematological group-myeloid and lymphoid-of diseases, with a special consideration for children with acute leukaemia.

Varicella Vaccination of Children With Leukemia Without Interruption of Maintenance Therapy: A Danish Experience

BACKGROUND

Varicella-zoster virus (VZV) can be fatal or cause severe complications in children with acute lymphoblastic leukemia (ALL). This analysis set out to investigate the morbidity and mortality of VZV vaccination without interruption of maintenance therapy in children with ALL.

METHODS

Files of 73 seronegative children with ALL were examined for data regarding VZV vaccination and infection, and long-term seroconversion was measured. Criteria before VZV vaccination were (1) seronegative, (2) in complete remission, (3) age ≥ 1.0 year, (4) lymphocyte count ≥ 0.6 × 10/L at time of vaccination and (5) receiving maintenance therapy.

RESULTS

Forty-five children were vaccinated. No child died or experienced serious adverse events due to VZV vaccination. Nine children developed late chickenpox despite vaccination. Long-term protection was found in 86% of children not receiving acyclovir and 78% of the entire population. Long-term seroconversion was found in 52% of the children. There were no severe cases of varicella infection. Acyclovir prophylaxis postvaccination was associated with an increased risk of late chickenpox [hazard ratio = 5.40 (1.43, 20.41), P = 0.01]. In contrast, a vaccine-induced rash reduced the risk of late chickenpox [hazard ratio = 0.08 (0.01, 0.66), P = 0.02]. No child had interruption of maintenance therapy at the time of vaccination, but 33% experienced discontinuation of therapy due to vaccine-induced rash. Dexamethasone was associated with an increased risk of vaccine-induced rash [hazard ratio = 2.9 (1.21, 6.90), P = 0.02].

CONCLUSIONS

This analysis indicates that VZV vaccination is feasible and justified in seronegative children with ALL, in countries where VZV vaccination is not part of the national vaccination program.

Varicella in pediatric oncology patients in the post-vaccine era-Analysis of routine hospital data from Bavaria (Germany), 2005-2011

Varicella in oncology patients can result in serious complications. We analyzed trends in hospitalization rates and characteristics of pediatric oncology and non-oncology patients hospitalized with varicella during the first 7 years after introduction of routine varicella vaccination. Our data included children <17 years of age with an International Classification of Diseases and Related Health Problems, 10th Revision (ICD-10) main or secondary discharge diagnosis of varicella identified by annual database queries in 22-29 pediatric hospitals in Bavaria (Germany) in 2005-2011. Of a total of 1,245 varicella-associated hospitalizations, 42 children (median age 4 years, interquartile range 3-5) had an underlying malignancy (67% with acute lymphoblastic leukemia). Overall, additional diagnoses potentially associated with varicella were reported less often in oncology than in non-oncology varicella patients (62% vs. 77%, p = 0.041), suggesting earlier hospitalization of high-risk patients. Acute hematological diagnoses (29% vs. 3%, p < 0.001) and coinfections (invasive 12% vs. 2%, p = 0.001; noninvasive 19% vs. 8%, p = 0.019) were more frequent, whereas neurological (5% vs. 19%, p = 0.023) and upper respiratory tract diagnoses (2% vs. 16%, p = 0.014) were less frequent in oncology compared to non-oncology varicella patients. Oncology varicella patients showed a longer hospital stay (median 5 vs. 3 days, p < 0.001). Hospitalization rates in non-oncology varicella patients declined constantly since 2006, from 114.8 (2006) to 30.5 (2011) per 1,000 pediatric beds. The rates of varicella-associated hospitalizations in oncology patients indicated an overall decreasing trend (3.8, 1.9, 4.6, 3.5, 0.4, 2.1 and 0.6 cases per 1,000 pediatric beds in 2005-2011). Thus, pediatric oncology patients potentially profit from herd protection effects, resulting from increasing vaccine coverage in the general population.

Incidence and case-fatality of varicella-zoster virus infection among pediatric cancer patients in developing countries

Limited evidence is available about varicella-zoster virus (VZV) infection among pediatric cancer patients in developing countries, which raises questions about the generalizability of VZV vaccine recommendations for pediatric cancer patients (derived from developed countries) to these settings. We assessed the incidence and case-fatality of VZV infection at three institutions in developing countries (Argentina, Mexico, and Nicaragua). Individuals eligible for our study were aged <20 years and actively receiving cancer-directed therapy. We estimated a summary incidence rate (IR) and case-fatality risk with corresponding 95 % confidence limits (CL) of VZV infection across sites using random-effects models. Our study population comprised 511 pediatric cancer patients, of whom 64 % were aged <10 years, 58 % were male, and 58 % were diagnosed with leukemia. We observed a total of 10 infections during 44,401 person-days of follow-up across the 3 sites (IR = 2.3, 95 % CL 1.2, 4.2). The summary case-fatality risk was 10 % (95 % CL 1.4, 47 %) based on one death.

CONCLUSION

Our results suggest low incidence and case-fatality of VZV infections among pediatric cancer patients in three developing countries. VZV vaccine recommendations for pediatric cancer patients in developed countries may be generalizable to developing countries.

WHAT IS KNOWN

• Current recommendations, based on evidence from pediatric cancer patients in developed countries, contraindicate varicella-zoster virus (VZV) vaccination until completion of cancer-directed therapy and recovery of immune function. • The generalizability of these VZV vaccine recommendations to pediatric cancer patients in developing countries is unknown because of limited information about the incidence and case-fatality of VZV in these settings. What is New: • Our results suggest low incidence and case-fatality of VZV infections among pediatric cancer patients in three developing countries. • VZV vaccine recommendations based on evidence from pediatric cancer patients in developed countries may be generalizable to pediatric cancer patients in developing countries.

Varicella vaccination in pediatric oncology patients without interruption of chemotherapy

BACKGROUND

Morbidity and mortality from primary varicella-zoster virus (VZV) infection is increased in immunocompromised children. Vaccination of VZV-seronegative cancer patients with live-attenuated varicella vaccine is safe when chemotherapy is interrupted. However, VZV vaccination without interruption of chemotherapy would be preferable.

OBJECTIVE

To vaccinate VZV-seronegative pediatric oncology patients with live-attenuated VZV vaccine without interrupting their chemotherapy.

STUDY-DESIGN

We performed a single-center prospective cohort study.

RESULTS

Thirty-one patients with either a hematological malignancy (n=24) or a solid tumor (n=7) were vaccinated early during their course of chemotherapy. VZV IgG seroconversion occurred in 14 of the 31 patients (45%) after one vaccination. Only 20 patients were revaccinated after 3 months. These were patients who did not seroconvert (5 patients) and patients who serocoverted (15 patients) to induce or sustain seropositivity. Of these 20 patients the final seroconversion rate was 70%. Seven out of the 31 patients (23%) developed a mild rash of which 5 were treated with antivirals and recovered completely without interrupting chemotherapy, and 2 recovered untreated. Of these 31 immunized patients 26 were available for cellular testing. After one vaccination 20 of 26 patients (77%) tested positive for VZV-specific CD4(+) T cells, of which 7 patients had remained VZV-seronegative. After the second vaccination 11 of 11 patients showed VZV-specific CD4(+) T cells to sustain positivity, although 4 remained VZV-seronegative.

CONCLUSIONS

This study indicates that live-attenuated VZV vaccine can be safely administered to closely monitored pediatric oncology patients without interruption of chemotherapy and adaptive immunity was induced despite incomplete seroconversion.

Vaccinations in patients with hematological malignancies

Patients with hematological malignancies are at risk for a number of infections that are potentially preventable by vaccinations such as pneumococcal infections and influenza. Treatment, especially with anti-B-cell antibodies and hematopoietic stem cell transplantation (HSCT), negatively impacts the response to vaccination for several months. It is therefore recommended that patients be vaccinated before initiating immunosuppressive therapy if possible. The risk of side-effects with inactivated vaccines is low, but care has to be taken with live vaccines, such as varicella-zoster virus vaccine, since severe and fatal complications have been reported. HSCT patients require repeated doses of most vaccines to achieve long-lasting immune responses. New therapeutic options for patients with hematological malignancies that are rapidly being introduced into clinical practice will require additional research regarding the efficacy of vaccinations. New vaccines are also in development that will require well-designed studies to ascertain efficacy and safety.

Vaccination in patients with primary immune deficiency, secondary immune deficiency and autoimmunity with immune regulatory abnormalities

Vaccination has been an important healthcare measure in preventing infectious diseases. The response to vaccination is reduced in immunocompromised patients, primary immune deficiency (PID) and secondary immune deficiency (SID), but vaccination studies still demonstrated a protective effect resulting in reducing complications, hospitalization, treatment costs and even mortality. The primary physician and the specialist directing patient care are responsible for vaccination. Live vaccines are contraindicated in patients with severe immune impairment, killed vaccines are highly recommended in PID and SID. Criteria have been defined to distinguish high- or low-level immune impairment in the different disease entities among PID and SID patients. For patients who do not respond to diagnostic vaccination as characterized by antibody failure immunoglobulin replacement is the mainstay of therapy.

Infectious complications in children with acute lymphoblastic leukemia treated in low-middle-income countries

Infections are the most important cause of morbidity and mortality in children treated for acute lymphoblastic leukemia (ALL). The rates of infection-associated mortality are up to 10-times higher in low- and middle-income countries (LMIC) than in high-income countries. The prevention, early recognition and management of infectious complications is especially challenging in LMIC because of disease and poverty-related factors, as well as the shortage of trained personnel, supplies, diagnostic tools and adequate organizational infrastructure. Children in LMIC with ALL, who are frequently underweight, are at increased risk of community-acquired pathogens, nosocomial multidrug-resistant pathogens and opportunistic microorganisms. This review summarizes the challenges of managing the major categories of infections in children receiving treatment for ALL and provides updated practical recommendations for preventing and managing these infections in LMIC.

Practical review of immunizations in adult patients with cancer

Compared with the general population, patients with cancer in general are more susceptible to vaccine-preventable infections, either by an increased risk due to the malignancy itself or immunosuppressive treatment. The goal of immunizations in these patients is therefore to provide protection against these infections, and to decrease the number of vulnerable patients who can disseminate these organisms. The proper timing of immunization with cancer treatment is key to achieving better vaccine protection. As the oncology field continues to advance, leading to better quality of life and longer survival, immunization and other aspects of preventive medicine ought to move to the frontline in the care of these patients. Herein, we review the vaccines most clinically relevant to patients with cancer, as well as special cases including vaccines after splenectomy, travel immunization and recommendations for family members.

Varicella zoster immune status in children treated for acute leukemia

Children treated for acute leukemia are at increased risk of severe infection with varicella zoster virus (VZV). We studied the VZV sero-status of children with acute leukemia prior to starting chemotherapy and after completion of chemotherapy. VZV sero-status was assessed using time resolved fluorescence immunoassay (TRFIA) before starting treatment and 6 months after completion of treatment. Prior to starting treatment for acute leukemia, a significant proportion of children (35%) are VZV seronegative. On completion of treatment most patients maintained protective VZV antibody levels; however, 35% had reduced/loss VZV antibody to a level considered non-protective and susceptible to VZV infection.

Guidelines on vaccinations in paediatric haematology and oncology patients

OBJECTIVE

Vaccinations are the most important tool to prevent infectious diseases. Chemotherapy-induced immune depression may impact the efficacy of vaccinations in children.

PATIENTS AND METHODS

A panel of experts of the supportive care working group of the Italian Association Paediatric Haematology Oncology (AIEOP) addressed this issue by guidelines on vaccinations in paediatric cancer patients. The literature published between 1980 and 2013 was reviewed.

RESULTS AND CONCLUSION

During intensive chemotherapy, vaccination turned out to be effective for hepatitis A and B, whilst vaccinations with toxoid, protein subunits, or bacterial antigens should be postponed to the less intensive phases, to achieve an adequate immune response. Apart from varicella, the administration of live-attenuated-virus vaccines is not recommended during this phase. Family members should remain on recommended vaccination schedules, including toxoid, inactivated vaccine (also poliomyelitis), and live-attenuated vaccines (varicella, measles, mumps, and rubella). By the time of completion of chemotherapy, insufficient serum antibody levels for vaccine-preventable diseases have been reported, while immunological memory appears to be preserved. Once immunological recovery is completed, usually after 6 months, response to booster or vaccination is generally good and allows patients to be protected and also to contribute to herd immunity.

The host immune response to varicella zoster virus

Varicella zoster virus (VZV) is a highly successful human pathogen, which is never completely eliminated from the host. VZV causes two clinically distinct diseases, varicella (chickenpox) during primary infection and herpes zoster (shingles) following virus reactivation from latency. Throughout its lifecycle the virus encounters the innate and adaptive immune response, and in order to prevent eradication it has developed many mechanisms to evade and overcome these responses. This review will provide a comprehensive overview of the host immune response to VZV infection, during the multiple stages of the virus lifecycle and at key sites of VZV infection. We will also briefly describe some of the strategies employed by the virus to overcome the host immune response and the ongoing challenges in further elucidating the interplay between VZV and the host immune response in an attempt to lead to better therapies and a ‘second generation’ vaccine for VZV disease.

Epidemiology and potential preventative measures for viral infections in children with malignancy and those undergoing hematopoietic cell transplantation

In pediatric patients with malignancy and those receiving hematopoietic stem cell transplants, bacterial and fungal infections have been the focus of fever and neutropenia episodes for decades. However, improved diagnostic capabilities have revealed viral pathogens as a significant cause of morbidity and mortality. Because of limited effective antiviral therapies, prevention of viral infections is paramount. Pre-exposure and post-exposure prophylaxis and antiviral suppressive therapeutic approaches are reviewed. Additionally, infection control practices specific to this patient population are discussed. A comprehensive approach utilizing each of these can be effective at reducing the negative impact of viral infections.

Vaccination in children with cancer: a debate

Children with malignancy present an important alteration of the immune system functionality caused by the illness itself and by the therapy they undergo. Therefore, they are at high risk of contracting vaccine-preventable diseases and of developing important complications. Vaccinations represent valid devices against these infections but this condition involves two main problems: are vaccines safe in these patients? Are vaccines effective in these patients? The aim of this review is to discuss the principles of vaccination management in children with cancer.

How to manage vaccinations in children with cancer

The optimal use of routine childhood immunizations in children with malignancy is still a matter of debate. Despite their higher risk of contracting vaccine preventable diseases and of suffering important complications, there is little understanding of the magnitude of the possible benefit of administering active immunization in this population due to a paucity of clinical trial data. Our review focuses on the management of children with cancer and offers some suggestions regarding their vaccination schedules.