Respiratory syncytial virus infection outbreak among pediatric patients with oncologic diseases and/or BMT

Approach to hematopoietic cell transplant candidates with respiratory viral detection

The management of respiratory viruses prior to hematopoietic cell transplant (HCT) can be controversial and requires special consideration of host factors, transplant parameters, and the specific respiratory virus (RV). In the setting of adenovirus (ADV), human metapneumovirus (HMPV), influenza, parainfluenza virus (PIV), and respiratory syncytial virus (RSV) detection prior to hematopoietic cell transplant (HCT), clinical practice guidelines recommend transplant delay when possible; however, there is much more ambiguity when other respiratory viruses, such as seasonal coronaviruses (CoVs), human rhinovirus (HRV), and SARS-CoV-2, are detected. Our aims for this review include detailing clinical practical guidelines and reviewing current literature on pre-transplant respiratory viral infections (RVIs), including antiviral therapies and prevention strategies, when available. We will center our discussion on three representative clinical scenarios, with the goal of providing practical guidance to clinicians.

Exploring Viral Metagenomics in Pediatric Patients with Acute Respiratory Infections: Unveiling Pathogens beyond SARS-CoV-2

The emergence of SARS-CoV-2 and the subsequent pandemic have prompted extensive diagnostic and clinical efforts to mitigate viral spread. However, these strategies have largely overlooked the presence of other respiratory viruses. Acute respiratory diseases in pediatric patients can be caused by a diverse range of viral agents, and metagenomics represents a powerful tool for their characterization. This study aimed to investigate the viral abundance in pediatric patients with acute respiratory symptoms who tested negative for SARS-CoV-2 during the Omicron pandemic wave. To achieve this, viral metagenomics and next-generation sequencing were employed on 96 nasopharyngeal swab samples, which were organized into 12 pools, with each pool consisting of eight individual samples. Metagenomic analysis revealed that the most prevalent viruses associated with acute disease in pediatric patients were respiratory syncytial virus (detected in all pools) and enteroviruses, which are known to cause significant morbidity and mortality in children. Additionally, clinically significant viruses such as mumps orthorubulavirus, human metapneumovirus, influenza A, and a wide array of human herpesviruses (1, 3-7) were identified. These findings highlight the extensive potential of viral metagenomics in identifying viruses other than SARS-CoV-2 that contribute to acute infections in children. Consequently, this methodology should garner clinical attention in terms of differential diagnosis and the development of public policies to address such conditions in the global pediatric population.

Development and qualification of cell-based relative potency assay for a human respiratory syncytial virus (RSV) mRNA vaccine

Respiratory syncytial virus (RSV) is a leading cause of severe lower respiratory tract infections worldwide. A safe and effective RSV vaccine has been an elusive goal but recent advances in vaccine technology have improved the likelihood that a vaccine for the prevention of RSV could be licensed in near future. We have developed an RSV vaccine V171 consisting of four lipids and messenger ribonucleic acid (mRNA) encoding an engineered form of the RSV F protein stabilized in its prefusion conformation. The lipids form lipid nanoparticles (LNP) with mRNA encapsulated during process, which protects the mRNA from degradation and enables the mRNA to be delivered into mammalian cells. Once inside the cells, the mRNA then can be translated into RSV F protein and elicit both humoral and cellular immune responses. Preclinical results and Phase I clinical trial results indicate that this mRNA vaccine targeting RSV F protein is a promising RSV vaccine approach and should be further evaluated in clinical trials. We have developed a cell-based relative potency assay to support the Phase II development of this vaccine. Test articles and a reference standard are tested with serial dilutions in a 96-well plate pre-seeded with Hep G2 cells. Cells were incubated for 16-18 h after transfection and then permeabilized and stained with a human monoclonal antibody specific to RSV F protein, followed by a fluorophore-conjugated secondary antibody. The plate is then analyzed for percentage of transfected cells and relative potency of the test article is calculated by comparing its EC50 to that of a reference standard. This assay takes advantage of the fact that due to the inherent variability in biological test systems an absolute measure of potency is more variable than a measure of activity relative to a standard. Targeting testing relative potency range 25-250 %, our assay showed an R2 close to 1 for linearity, relative bias of 1.05-5.41 %, and intermediate precision of 11.0 %. The assay has been used for testing of process development samples, formulation development samples, as well as drug product intermediate (DPI) and drug product (DP) in support of Phase II development of our RSV mRNA vaccine.

Review of the Safety, Efficacy and Tolerability of Palivizumab in the Prevention of Severe Respiratory Syncytial Virus (RSV) Disease

Respiratory Syncytial Virus (RSV) is a major global cause of childhood morbidity and mortality. Palivizumab, a monoclonal antibody that provides passive immunity against RSV, is currently licensed for prophylactic use in specific "high-risk" populations, including congenital heart disease, bronchopulmonary dysplasia and prematurity. Available research suggests palivizumab use in these high-risk populations can lead to a reduction in RSV-related hospitalization. However, palivizumab has not been demonstrated to reduce mortality, adverse events or length of hospital stay related to RSV. In this article, we review the management of RSV, indications for palivizumab prophylaxis, the safety, cost-effectiveness and efficacy of this preventative medication, and emerging therapeutics that could revolutionize future prevention of this significant pathogen.

Challenges in the prevention or treatment of RSV with emerging new agents in children from low- and middle-income countries

INTRODUCTION

Respiratory syncytial virus (RSV) causes approximately 120,000 deaths annually in children <5 years, with 99% of fatalities occurring in low- and middle-income countries (LMICs).

AREAS COVERED

There are numerous RSV interventions in development, including long-acting monoclonal antibodies, vaccines (maternal and child) and treatments which are expected to become available soon. We reviewed the key challenges and issues that need to be addressed to maximize the impact of these interventions in LMICs. The epidemiology of RSV in LMICs was reviewed (PubMed search to 30 June 2020 inclusive) and the need for more and better-quality data, encompassing hospital admissions, community contacts, and longer-term respiratory morbidity, emphasized. The requirement for an agreed clinical definition of RSV lower respiratory tract infection was proposed. The pros and cons of the new RSV interventions are reviewed from the perspective of LMICs.

EXPERT OPINION

We believe that a vaccine (or combination of vaccines, if practicable) is the only viable solution to the burden of RSV in LMICs. A coordinated program, analogous to that with polio, involving governments, non-governmental organizations, the World Health Organization, the manufacturers and the healthcare community is required to realize the full potential of vaccine(s) and end the devastation of RSV in LMICs.

Antigenic Site-Specific Competitive Antibody Responses to the Fusion Protein of Respiratory Syncytial Virus Were Associated With Viral Clearance in Hematopoietic Cell Transplantation Adults

Background: Recent studies of human sera showed that the majority of the respiratory syncytial virus (RSV) neutralizing antibodies are directed against pre-fusion conformation of the fusion (F) protein of RSV and revealed the importance of pre-fusion antigenic site Ø specific antibodies. However, detailed analysis of multiple antigenic site-specific competitive antibody responses to RSV F protein and their contribution to virus clearance in humans are lacking. Methods: We prospectively enrolled a cohort of RSV infected hematopoietic cell transplantation (HCT) adults (n = 40). Serum samples were collected at enrollment (acute, n = 40) and 14 to 60 days post-enrollment (convalescent, n = 40). Antigenic site-specific F protein antibodies were measured against pre-fusion site Ø, post-fusion site I, and sites II and IV present in both the pre-fusion and post-fusion F protein conformations utilizing four different competitive antibody assays developed with biotinylated monoclonal antibodies (mAb) D25, 131-2A, palivizumab, and 101F, respectively. The lower limit of detection were 7.8 and 1.0 μg/mL for the competitive antibody assays that measured site Ø specific response, as well as sites I, II, and IV specific responses, respectively. Neutralizing antibody titers to RSV A and B subgroups was determined by microneutralization assays. Results: The overall findings in RSV infected HCT adults revealed: (1) a significant increase in antigenic site-specific competitive antibodies in convalescent sera except for site Ø competitive antibody (p < 0.01); (2) comparable concentrations in the acute and convalescent serum samples of antigenic site-specific competitive antibodies between RSV/A and RSV/B infected HCT adults (p > 0.05); (3) significantly increased concentrations of the antigenic site-specific competitive antibodies in HCT adults who had genomic RSV detected in the upper respiratory tract for <14 days compared to those for ≥14 days (p < 0.01); and (4) statistically significant correlation between the antigenic site-specific competitive antibody concentrations and neutralizing antibody titers against RSV/A and RSV/B (r ranged from 0.33 to 0.83 for acute sera, and 0.50-0.88 for convalescent sera; p < 0.05). Conclusions: In RSV infected HCT adults, antigenic site-specific antibody responses were induced against multiple antigenic sites found in both the pre-fusion and post-fusion F conformations, and were associated with a more rapid viral clearance and neutralizing antibody activity. However, the association is not necessarily the cause and the consequence.

Risk stratification of immunocompromised children, including pediatric transplant recipients at risk of severe respiratory syncytial virus disease

BACKGROUND

Respiratory syncytial virus (RSV) infection is associated with increased morbidity and mortality in immunocompromised patients. Our goal was to develop a framework for risk stratifying immunocompromised patients, including transplant patients, for RSV prophylaxis.

METHODS

Risk factors for severe RSV disease in immunocompromised patients were identified in the literature and by an expert panel via survey. Experts assigned a probability of developing severe disease (0 to 100 scale) to the risk factors for each immunocompromised population. The results were validated using a clinical dataset. Linear mixed models adjusted for within-expert clustering of ranks were used to estimate average scores, and differences were tested using paired t tests. Logistic regression was utilized to identify important determinants of severe RSV disease.

RESULTS

The survey was emailed to twenty-seven experts and thirteen responded (48%). Across all transplant groups, age <2 years (mean 77.1, 95% CI 71.7, 82.5) and day care attendance (mean 72.8, 95% CI 67.3, 78.3) were assigned the highest risk of severe disease. The highest risk groups were lung transplant recipients (mean 73.2, 95% CI 67.6, 78.8), combined lung and heart transplant recipients (mean 75.2, 95% CI 69.6, 80.7), allogeneic stem cell transplant (mean 76.0, 95% CI 70.4, 81.6), and severe combined immunodeficiency (mean 74.7, 95% CI 69.1, 80.3).

CONCLUSION

The results provide a logical validity to current practice and provide guidance for prioritizing patients to receive prophylactic agents to prevent severe RSV disease. The results will facilitate the development of a risk stratification tool for RSV prophylaxis for immunocompromised patients.

Oral ribavirin for paramyxovirus infection after alemtuzumab-containing reduced-intensity conditioning HCT regimen

Aerosolized ribavirin has been used in pediatric immunocompromised patients to treat acute respiratory viral infections, but oral ribavirin may be a less expensive alternative that allows for outpatient therapy. Oral ribavirin has compared favorably to aerosolized ribavirin in adult studies, but data on safety are lacking in pediatric populations. Four cases are described in which oral ribavirin was used to treat viral respiratory infections in recipients of allogeneic hematopoietic stem cell transplants at a Children's Hospital, demonstrating safety and feasibility.

Active prophylaxis for respiratory syncytial virus: current knowledge and future perspectives

Respiratory syncytial virus (RSV) is the most common respiratory pathogen in infants and young children but represents also an important cause of morbidity in adults, particularly in the elderly and immunocompromised persons. Despite its global impact on human health, no effective treatment is available except for supportive care and no safe vaccine has been licensed yet. Vaccine development has been hindered by several factors including vaccine enhanced disease associated with formalin-inactivated RSV vaccine, ethical concerns and lack of consensus concerning the most appropriate target antigen. In this review, we analyze history of RSV vaccine and current approaches for preventing RSV including live-attenuated, vector-based, subunit, nucleic acid-based, particle-based vaccines and we debate about concerns on target population, correlates of protection and obstacles that are slowing the progress toward a successful RSV vaccination strategy.

Comparative effectiveness of aerosolized versus oral ribavirin for the treatment of respiratory syncytial virus infections: A single-center retrospective cohort study and review of the literature

BACKGROUND

Respiratory syncytial virus (RSV) is a leading cause of viral infections in immunocompromised hosts and is associated with significant morbidity and mortality. In January 2015, our institution switched from aerosolized to oral ribavirin (RBV) for primary treatment of RSV infection among high-risk immunocompromised adult patients. The objective of the study was to evaluate the clinical and economic outcomes associated with this switch.

METHODS

Retrospective cohort analysis of adult patients diagnosed with RSV infection and treated with RBV between January 1, 2013, and May 31, 2016.

RESULTS

Of 46 patients, 20 (43%) patients received oral RBV and 26 (57%) received aerosolized RBV. Underlying conditions included lung transplant (n = 22), hematopoietic cell transplant (n = 16), hematological malignancy (n = 5), and structural lung diseases (n = 4). At the time of RSV diagnosis, 42 (91%) were hospitalized, 36 (78%) had clinical and radiographic evidence of lower respiratory tract infection (RTI), 9 (20%) were admitted to the ICU, and 4 (9%) required intubation. There were no differences in clinical outcomes between the 2 groups with regard to adverse events, progression from upper to lower RTI, escalation of care, or 30-day mortality. Three (15%) in the oral group and 1 (4%) in the aerosolized group died within 30 days (P = .33). The cost avoidance attributable to the switch in therapy over 1 year is $1.2 million.

CONCLUSION

Oral RBV appears to be a safe and cost-effective alternative to aerosolized RBV for the management of RSV infection in immunocompromised patients. Larger studies are needed to validate the safety and efficacy of this approach.

Past, Present and Future Approaches to the Prevention and Treatment of Respiratory Syncytial Virus Infection in Children

INTRODUCTION

The REGAL (RSV Evidence - A Geographical Archive of the Literature) series has provided a comprehensive review of the published evidence in the field of respiratory syncytial virus (RSV) in Western countries over the last 20 years. This seventh and final publication covers the past, present and future approaches to the prevention and treatment of RSV infection among infants and children.

METHODS

A systematic review was undertaken of publications between January 1, 1995 and December 31, 2017 across PubMed, Embase and The Cochrane Library. Studies reporting data on the effectiveness and tolerability of prophylactic and therapeutic agents for RSV infection were included. Study quality and strength of evidence (SOE) were graded using recognized criteria. A further nonsystematic search of the published literature and Clinicaltrials.gov on antiviral therapies and RSV vaccines currently in development was also undertaken.

RESULTS

The systematic review identified 1441 studies of which 161 were included. Management of RSV remains centered around prophylaxis with the monoclonal antibody palivizumab, which has proven effective in reducing RSV hospitalization (RSVH) in preterm infants < 36 weeks' gestational age (72% reduction), children with bronchopulmonary dysplasia (65% reduction), and infants with hemodynamically significant congenital heart disease (53% reduction) (high SOE). Palivizumab has also shown to be effective in reducing recurrent wheezing following RSVH (high SOE). Treatment of RSV with ribavirin has conflicting success (moderate SOE). Antibodies with increased potency and extended half-life are currently entering phase 3 trials. There are approximately 15 RSV vaccines in clinical development targeting the infant directly or indirectly via the mother.

CONCLUSION

Palivizumab remains the only product licensed for RSV prophylaxis, and only available for high-risk infants. For the general population, there are several promising vaccines and monoclonal antibodies in various stages of clinical development, with the aim to significantly reduce the global healthcare impact of this common viral infection.

FUNDING

AbbVie.

Molecular characteristics and successful management of a respiratory syncytial virus outbreak among pediatric patients with hemato-oncological disease

Background

Respiratory syncytial virus (RSV) is responsible for upper and lower respiratory tract infection in adults and children. Especially immunocompromised patients are at high risk for a severe course of infection, and mortality is increased. Moreover RSV can spread in healthcare settings and can cause outbreaks. Herein we demonstrate the successful control and characteristics of a RSV outbreak that included 8 patients in our Department of Pediatric Hematology and Oncology.

Methods

We performed an epidemiologic investigation and a molecular analysis of the outbreak strains. Moreover we present the outbreak control bundle and our concept for RSV screening in the winter season.

Results

RSV A and B strains caused the outbreak. RSV B strains affected 3 patients, 2 of whom were co-infected with RSV A. Exactly this RSV A strain was detected in another 5 patients. Our multimodal infection control bundle including prophylactic RSV screening was able to rapidly stop the outbreak.

Conclusion

An infection control bundle in RSV outbreaks should address all potential transmission pathways. In pediatric settings the restriction of social activities might have a temporal negative impact on quality of life but helps to limit transmission opportunities. Molecular analysis allows better understanding of RSV outbreaks and, if done in a timely manner, might be helpful for guidance of infection control measures.

Respiratory syncytial virus elicits enriched CD8+ T lymphocyte responses in lung compared with blood in African green monkeys

Respiratory syncytial virus (RSV) is a leading cause of serious lower respiratory tract disease in young children and older adults throughout the world. Prevention of severe RSV disease through active immunization is optimal but no RSV vaccine has been licensed so far. Immune mechanisms of protection against RSV infection in humans have not been fully established, thus a comprehensive characterization of virus-specific immune responses in a relevant animal model will be beneficial in defining correlates of protection. In this study, we infected juvenile naive AGMs with RSV A2 strain and longitudinally assessed virus-specific humoral and cellular immune responses in both peripheral blood and the respiratory tract. RSV viral loads at nasopharyngeal surfaces and in the lung peaked at around day 5 following infection, and then largely resolved by day 10. Low levels of neutralizing antibody titers were detected in serum, with similar kinetics as RSV fusion (F) protein-binding IgG antibodies. RSV infection induced CD8+, but very little CD4+, T lymphocyte responses in peripheral blood. Virus-specific CD8+ T cell frequencies were ~10 fold higher in bronchoaveolar lavage (BAL) compared to peripheral blood and exhibited effector memory (CD95+CD28-) / tissue resident memory (CD69+CD103+) T (TRM) cell phenotypes. The kinetics of virus-specific CD8+ T cells emerging in peripheral blood and BAL correlated with declining viral titers, suggesting that virus-specific cellular responses contribute to the clearance of RSV infection. RSV-experienced AGMs were protected from subsequent exposure to RSV infection. Additional studies are underway to understand protective correlates in these seropositive monkeys.

Defining the Incidence and Associated Morbidity and Mortality of Severe Respiratory Syncytial Virus Infection Among Children with Chronic Diseases

INTRODUCTION

REGAL (RSV Evidence-a Geographical Archive of the Literature) has provided a comprehensive review of the published evidence in the field of respiratory syncytial virus (RSV) in Western countries over the last 20 years. This review covers the risk and burden of RSV infection in children with underlying medical conditions or chronic diseases (excluding prematurity and congenital heart disease).

METHODS

A systematic review of publications between January 1, 1995 and December 31, 2015 across PubMed, Embase, The Cochrane Library, and Clinicaltrials.gov was supplemented by papers identified by the authors through March 2017. Studies reporting data for hospital visits/admissions for RSV infection as well as studies reporting RSV-associated morbidity and mortality were included. Study quality and strength of evidence (SOE) were graded.

RESULTS

A total of 2703 studies were identified and 58 were included. Down syndrome, irrespective of prematurity and congenital heart disease (moderate SOE), immunocompromised children (low SOE), cystic fibrosis (low SOE), and neurologic conditions (low SOE) were associated with a significantly increased risk of RSV hospitalization. A number of other congenital malformations and chronic conditions were also associated with severe RSV disease (low SOE). In general, pre-existing disease was also a predisposing factor for RSV-related mortality (low SOE).

CONCLUSION

Severe RSV infection in infants and young children with underlying medical conditions or chronic diseases poses a significant health burden. Further studies are needed to fully quantify the epidemiology, burden and outcomes in these populations, in particular RSV-attributable mortality.

Risk of nosocomial respiratory syncytial virus infection and effectiveness of control measures to prevent transmission events: a systematic review

Respiratory syncytial virus (RSV) causes a significant public health burden, and outbreaks among vulnerable patients in hospital settings are of particular concern. We reviewed published and unpublished literature from hospital settings to assess: (i) nosocomial RSV transmission risk (attack rate) during outbreaks, (ii) effectiveness of infection control measures. We searched the following databases: MEDLINE, EMBASE, CINAHL, Cochrane Library, together with key websites, journals and grey literature, to end of 2012. Risk of bias was assessed using the Cochrane risk of bias tool or Newcastle–Ottawa scale. A narrative synthesis was conducted. Forty studies were included (19 addressing research question one, 21 addressing question two). RSV transmission risk varied by hospital setting; 6–56% (median: 28·5%) in neonatal/paediatric settings (n = 14), 6–12% (median: 7%) in adult haematology and transplant units (n = 3), and 30–32% in other adult settings (n = 2). For question two, most studies (n = 13) employed multi‐component interventions (e.g. cohort nursing, personal protective equipment (PPE), isolation), and these were largely reported to be effective in reducing nosocomial transmission. Four studies examined staff PPE; eye protection appeared more effective than gowns and masks. One study reported on RSV prophylaxis for patients (RSV‐Ig/palivizumab); there was no statistical evidence of effectiveness although the sample size was small. Overall, risk of bias for included studies tended to be high. We conclude that RSV transmission risk varies widely during hospital outbreaks. Although multi‐component control strategies appear broadly successful, further research is required to disaggregate the effectiveness of individual components including the potential role of palivizumab prophylaxis.

Respiratory syncytial virus infection in infants with acute leukemia: a retrospective survey of the Japanese Pediatric Leukemia/Lymphoma Study Group

Respiratory syncytial virus (RSV) can cause life-threatening complications of lower respiratory tract infection (LRTI) in young children with malignancies, but reports remain limited. We performed a retrospective nationwide survey to clarify the current status of RSV disease among infants with hematological malignancies. Clinical course, treatment, and outcome of patients with hematological malignancies who suffered from RSV infections at the age of <24 months during anti-tumor therapy from April 2006 to March 2009 were investigated by sending a questionnaire to all member institutions of the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG). Twelve patients with acute leukemia were identified as having experienced RSV disease. The primary diseases were acute myeloid leukemia (n = 8) and acute lymphoblastic leukemia (n = 4). RSV infection occurred pre- or during induction therapy (n = 8) and during consolidation therapy (n = 4). Eight patients developed LRTI, four of whom had severe pneumonia or acute respiratory distress syndrome; these four patients died despite receiving intensive care. In our survey, the prognosis of RSV disease in pediatric hematological malignancies was poor, and progression of LRTI in particular was associated with high mortality. In the absence of RSV-specific therapy, effective prevention and treatment strategies for severe RSV disease must be investigated.

Oral Ribavirin for the Treatment of Noninfluenza Respiratory Viral Infections: A Systematic Review

OBJECTIVE

To review clinical outcomes data for patients treated with oral ribavirin for noninfluenza respiratory viral infections (NIRVIs).

DATA SOURCES

MEDLINE, EMBASE, and PubMed Central (1972 to June 1, 2015) were queried with the following search term combinations: "Oral" AND "ribavirin" AND ("respiratory syncytial virus" OR "metapneumovirus" OR "parainfluenza" OR "coronavirus" OR "rhinovirus" OR "enterovirus" OR "adenovirus").

STUDY SELECTION AND DATA EXTRACTION

Included studies must have characterized the clinical outcomes of a cohort of patients treated with oral ribavirin for symptomatic NIRVIs. Case reports and series with <5 cases, conference abstracts, and articles written in languages other than English were excluded.

DATA SYNTHESIS

Of the 1256 unique reports, 15 met inclusion criteria: 12 retrospective, 3 prospective, and 3 comparative with untreated control groups. All studies except for 2 Middle East respiratory syndrome coronavirus (MERS-CoV) studies were in immunocompromised patients (9 malignancy/stem cell transplant, 4 lung transplant). The mortality rate ranged from 0% to 31% in malignancy/stem cell transplant recipients treated with oral ribavirin, and 1/108 (0.9%) ribavirin-treated lung transplant recipients died at 30 days. Three studies (one each for malignancy, lung transplant, and MERS-CoV) suggested a clinical outcomes benefit with oral ribavirin compared with supportive care alone; however, the nonrandomized design precludes efficacy determination. Hemolysis was the most common adverse reaction, occurring in 14% (54/375) of patients. Ribavirin was discontinued in 4% of patients secondary to adverse reactions.

CONCLUSIONS

Oral ribavirin should be considered for the treatment of NIRVI in immunocompromised adults (malignancy/stem cell transplant or lung transplant) or adults with MERS-CoV.

Translational sciences approach to RSV vaccine development

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants and the elderly. Despite its relatively low degree of antigenic variation, it causes frequent reinfection throughout life. Clinical manifestations of RSV disease and the immune response to infection differ in infants and the elderly, suggesting that vaccines designed to protect these two populations may require different attributes. Here, the authors describe the translational approach of utilizing data from epidemiology studies performed in these populations, the use of RSV diagnostics in clinical practice, lessons learned from previous vaccine clinical trials and the success of palivizumab in prevention of RSV disease in premature and high-risk infants to aid the development of safe and effective RSV vaccines.

Detection, control, and management of a respiratory syncytial virus outbreak in a pediatric hematology-oncology department

BACKGROUND

Immunocompromised patients are at increased risk for severe respiratory syncytial virus (RSV) infection. Palivizumab is approved for prevention of RSV in specific populations but not for treatment. Few studies demonstrated the safety and successful treatment with intravenous (IV) palivizumab. We describe our experience with IV palivizumab treatment for RSV in a pediatric hematology-oncology department during an outbreak.

METHODS

During a short period of renovations, oncology patients were placed in a general pediatric ward. After a case of severe fatal RSV pneumonia in a 2-year-old male patient with acute myeloid leukemia, all patients were actively screened twice weekly regardless of symptoms. Respiratory samples were tested for RSV using rapid immunochromatography detection, immunofluorescence, or reverse transcriptase polymerase chain reaction. A single dose of palivizumab (15 mg/kg) was given to children below 3 years of age who tested positive for RSV.

RESULTS

Over a 6-week period, 12 patients tested positive for RSV. Seven patients were treated with palivizumab. Five patients had respiratory symptoms, and 2 were asymptomatic. No adverse events were attributed to IV palivizumab treatment. Early-treated patients had no complications attributed to RSV.

CONCLUSIONS

Containment of RSV outbreak in high-risk children is difficult. Screening with reverse transcriptase polymerase chain reaction and the early use of IV palivizumab is safe and may prevent complications of RSV infection among these patients.

Respiratory syncytial virus lower respiratory tract infection in a pediatric liver transplant recipient treated with oral ribavirin

The mainstay of therapy for RSV disease is supportive care, although aerosolized ribavirin has been used to treat infants and young children with severe lower respiratory tract infections. Aerosolized ribavirin has adverse effects, high cost and teratogenic potential. We report the case of a pediatric liver transplant recipient diagnosed with lower respiratory RSV infection, who was successfully treated with oral ribavirin.

Intravenous ribavirin for respiratory syncytial viral infections in pediatric hematopoietic SCT recipients

Respiratory syncytial virus (RSV) is a potential cause of serious morbidity and even mortality among children undergoing hematopoietic SCT (HSCT). Contrary to the available information regarding the aerosolized formulation of ribavirin, there is a paucity of published studies using i.v. ribavirin in adults, and very few single reports on pediatric patients. Aerosolized drug administration has been limited by potential toxicity and special air-flow requirements. In this regard, i.v. ribavirin could prevent these disadvantages, but its efficacy and safety remain controversial in the pediatric HSCT setting. The present study describes the outcome of six pediatric patients undergoing HSCT with nine episodes of proven RSV. Four episodes corresponded to lower respiratory tract infection (LRTI) and five presented with upper respiratory tract infection (URTI). All LRTI patients showed favorable clinical responses, with 100% survival and no progression to LRTI in the remaining five URTI. No side effects were documented during ribavirin administration. We conclude that ribavirin was well tolerated intravenously, without associated side effects, and was effective in the treatment of RSV in this limited number of pediatric HSCT patients. The role and efficacy of i.v. ribavirin needs to be further clarified by prospective controlled trials in pediatric populations.

Multiple viral infections after haploidentical hematopoietic stem cell transplantation in a child with acute lymphoblastic leukemia

After allogeneic hematopoietic stem cell transplantation (HSCT), viral infections/reactivations are a frequent complication, sometimes with fatal outcome. Thus, early diagnosis is recommended by screening of whole blood or plasma preparations using highly sensitive molecular techniques that test for the most common viral pathogens, such as Epstein-Barr virus, cytomegalovirus, and adenoviruses (ADVs). Despite this approach, not every reactivation/infection can be adequately detected or excluded, even with highly sensitive polymerase chain reaction. Particularly after toxic treatment, uncommon infections or infections resistant to first-line treatment can occur, even in unusual locations. Herein, we present the case of a child with Philadelphia chromosome-positive acute lymphoblastic leukemia after allogeneic HSCT who suffered from 5 different viral reactivations/infections, including acyclovir-resistant herpes simplex virus type 1 esophagitis, human herpesvirus 6 encephalitis, rotavirus gastroenteritis, respiratory syncytial virus pneumonia, and ADV esophagitis, despite routinely performed blood examinations for viral pathogens remaining unrevealing at all times.

Prevalence and clinical course of viral upper respiratory tract infections in immunocompromised pediatric patients with malignancies or after hematopoietic stem cell transplantation

BACKGROUND

Respiratory tract infections (RTI) in immunosuppressed pediatric patients with malignancies or after hematopoietic stem cell transplantation (HSCT) are associated with significant morbidity and mortality. Prospective data on the incidence and clinical role of infections by respiratory viruses in this population have been lacking.

METHODS

In this prospective study, 191 children between 0 and 18 years of age were investigated by real-time polymerase chain reaction for the presence of 8 common respiratory virus types in transnasal aspirations. The study included 110 children with leukemia, lymphoma, or solid tumors (subgroup 1); 31 children after HSCT (subgroup 2); and 50 immunocompetent control patients.

RESULTS

In comparison with the control group, immunocompromised children showed a significantly higher incidence of positive virus tests (subgroup 1: 53%; subgroup 2: 81%; controls: 24%; P<0.0001), and more frequently experienced ensuing viral infections in the lower respiratory tract (subgroup 1: 74%; subgroup 2: 88%; controls: 25%; P<0.0001). Sixteen percent of these children had coinfections by 2 or more viruses and revealed more severe respiratory illness.

CONCLUSIONS

The present epidemiologic study on viral upper RTI in immunocompromised children revealed a high virus-associated morbidity which was particularly prominent in HSCT recipients. In these children, detection of viral coinfections was identified as a risk factor for a severe course of lower RTI.

Antibody response and avidity of respiratory syncytial virus-specific total IgG, IgG1, and IgG3 in young children

Respiratory syncytial virus (RSV) is a major cause of acute respiratory disease in infants and young children. Considering that several aspects of the humoral immune response to RSV infection remain unclear, this study aimed to investigate the occurrence, levels, and avidity of total IgG, IgG1, and IgG3 antibodies against RSV in serum samples from children ≤5 years old. In addition, a possible association between antibody avidity and severity of illness was examined. The occurrence and levels of RSV-specific IgG depended on age, with infants <3 months old displaying high levels of antibodies, which were probably acquired from the mother. Children ≥24 months old also showed frequent occurrence and high levels of IgG, which was produced actively during infection. In addition, the avidity assay showed that the avidity of RSV-specific total IgG and IgG1 was lower in infants <3 months old who had acute respiratory disease than in age-matched controls. The avidity of RSV-specific IgG detected in children ≥24 months old with lower respiratory infection was lower than that in children with upper respiratory infection. These results indicate that the presence of high avidity RSV-specific IgG antibodies may lead to better protection against RSV infection in children <3 months old, who may have a lower probability of developing disease of increased severity. In addition, children ≥24 months old with RSV-specific IgG antibodies of low avidity tended to develop more severe RSV illness. These findings may be helpful in establishing vaccination schedules when a vaccine becomes available.

[Children with cancer and respiratory viral infection: epidemiology, diagnosis and treatment options]

Community-adquired respiratory viral infection is the most common cause of febrile infection in children, and an important cause of infection to consider in children with cancer. Nevertheless, there are few well-designed, controlled studies in this population, which makes it difficult to understand the importance, behaviour and management of these viruses in immunocompromised children. New diagnostic techniques in PCR-based microbiology, could provide many opportunities for early diagnosis, preventing the spread of the virus and to implement the correct therapy. It is important to design appropriate prospective studies to assess these types of infections in children with cancer. In this review we analyse the main studies published in the literature, evaluating the epidemiology, diagnosis and management of children with cancer and respiratory viral infection.