Respiratory virus infections after marrow transplant: the Fred Hutchinson Cancer Research Center experience

Prognosis of hospitalized adult patients with respiratory syncytial virus infection: a multicenter retrospective cohort study

OBJECTIVES

Respiratory syncytial virus (RSV) is a common agent of viral respiratory infections with significant morbidity and mortality in adults. The objective of this study is to determine risk factors for mortality, invasive mechanical ventilation and to describe the characteristics of patients who received ribavirin.

METHODS

Retrospective multicenter observational cohort study conducted in Great Paris area hospitals, including patients hospitalized between January 1, 2015 and December 31, 2019 for documented RSV infection. Data were extracted from the AP-HP Health Data Warehouse. The primary endpoint was in-hospital mortality.

RESULTS

1168 patients were hospitalized for RSV infection, including 288 (24.6%) patients who required ICU admission. The median [interquartile range] age of patients was 75 [63-85] years, 54% (n=631/1168) of them were women. In-hospital mortality was 6.6% (n=77/1168) in the whole cohort and 12.8% (n=37/288) in ICU patients. Factors associated with hospital mortality were age>85 years (adjusted odds ratio (aOR)=6.29 95% confidence interval [2.47-15.98]), acute respiratory failure (aOR=2.83 [1.19-6.72]), non-invasive (aOR=12.60 [1.41-112.36]) and invasive mechanical ventilation support (aOR=30.13 [3.17-286.27]) and neutropenia (aOR=13.19 [3.27-53.27]). Factors associated with invasive mechanical ventilation were chronic heart (aOR=1.98 [1.20-3.26]) or respiratory failure (aOR=2.83 [1.67-4.80]), and co-infection (aOR=2.62 [1.60-4.30]). Patients who were treated with ribavirin were significantly younger than others (62 [55-69] vs 75 [63-86] years; p<0.001), more frequently males (n=34/48 (70.8%) vs n=503/1120 (44.9%); p=0.001), and almost exclusively immunocompromised (n=46/48 (95.8%) vs n=299/1120 (26.7%); p<0.001).

CONCLUSIONS

The mortality rate of patients hospitalized with RSV infections was 6.6%. Twenty-five percent of patients required ICU admission.

Therapeutic efficacy of monoclonal antibodies and antivirals against SARS-CoV-2 Omicron BA.1 in Syrian hamsters

The spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the major antigen stimulating the host's protective immune response. Here we assessed the efficacy of therapeutic monoclonal antibodies (mAbs) against Omicron variant (B.1.1.529) sublineage BA.1 variants in Syrian hamsters. Of the FDA-approved therapeutic mAbs tested (that is, REGN10987/REGN10933, COV2-2196/COV2-2130 and S309), only COV2-2196/COV2-2130 efficiently inhibited BA.1 replication in the lungs of hamsters, and this effect was diminished against a BA.1.1 variant possessing the S-R346K substitution. In addition, treatment of BA.1-infected hamsters with molnupiravir (a SARS-CoV-2 RNA-dependent RNA polymerase inhibitor) or S-217622 (a SARS-CoV-2 protease inhibitor) strongly reduced virus replication in the lungs. These findings suggest that the use of therapeutic mAbs in Omicron-infected patients should be carefully considered due to mutations that affect efficacy, and demonstrate that the antiviral compounds molnupiravir and S-217622 are effective against Omicron BA.1 variants.

Clinical experience of coronavirus disease 2019 in hematopoietic cell transplant and chimeric antigen receptor T-cell recipients

PURPOSE OF REVIEW

To discuss the clinical experience of coronavirus disease 2019 (COVID-19) in hematopoietic cell transplant and chimeric antigen receptor T-cell therapy recipients over the past year and to identify key knowledge gaps for future research.

RECENT FINDINGS

Immunocompromised individuals and those with chronic health conditions are especially susceptible to infections, which have had a disproportionate impact on health outcomes during the COVID-19 pandemic. Several studies have evaluated the clinical characteristics and outcomes of transplant and cellular therapy (TCT) recipients who developed COVID-19. Age, sex, comorbid conditions, and social determinants of health are important predictors of the risk of severe acute respiratory syndrome coronavirus 2 infection and of the eventual severity of the disease. Various treatment approaches have been investigated over the last year. The paradigm of management strategies continues to evolve as more experience is accumulated.

SUMMARY

In this review, we summarize some important findings as they relate to the clinical characteristics of TCT recipients who develop COVID-19. We also discuss some treatment approaches that are currently recommended and opine on vaccination in this population.

Clinical Effectiveness of Influenza Vaccination After Allogeneic Hematopoietic Stem Cell Transplantation: A Cross-sectional, Prospective, Observational Study

BACKGROUND

Vaccination is the primary method for preventing influenza respiratory virus infection (RVI). Although the influenza vaccine is able to achieve serological responses in some allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients, its clinical benefits are still uncertain.

METHODS

In this prospective, cross-sectional study, we retrospectively analyzed the effect of inactivated trivalent influenza vaccination on the prevalence of influenza RVI in a consecutive cohort of 136 allo-HSCT adult recipients who developed 161 RVI over 5 flu seasons (from 2013 to 2018). Respiratory viruses in upper- and/or lower-respiratory tract specimens were tested using multiplex polymerase chain reaction panel assays.

RESULTS

Overall, we diagnosed 74 episodes (46%) of influenza RVI in 70 allo-HSCT recipients. Influenza RVI occurred in 51% of the non-vaccinated compared to 36% of the vaccinated recipients (P = .036). A multivariate analysis showed that influenza vaccination was associated with a lower prevalence of influenza RVI (odds ratio [OR] 0.39, P = .01). A multivariate risk factor analysis of lower-respiratory tract disease (LRTD) identified 2 conditions associated with the probability of influenza RVI progression: influenza vaccination (OR 0.12, 95% confidence interval [CI] 0.014-1, P = .05) and a high-risk immunodeficiency score (OR 36, 95% CI 2.26-575, P = .011). Influenza vaccination was also associated with a lower likelihood of an influenza-related hospital admission (14% vs 2%, P = .04).

CONCLUSIONS

This study shows that influenza vaccination may have a clinical benefit in allo-HSCT recipients with virologically-confirmed RVI, in terms of a lower influenza RVI prevalence, slower LRTD progression, and lower likelihood of hospital admission.

Immunodeficiency risk score for prediction of mortality by parainfluenza virus infection in patients with hematologic malignancy

Parainfluenza virus (PIV) infection is a significant cause of morbidity and mortality, especially in hematologic malignancy patients including hematopoietic stem cell transplantation (HCT) recipients. However, limited information is available for risk stratification in PIV-infected patients with hematologic malignancy with or without HCT. Patients with hematologic malignancy diagnosed with PIV from January 2009 to December 2018 were retrospectively included in a tertiary care hospital in Seoul, South Korea. Upper respiratory tract infection (URTI) was defined as the detection of PIV in a nasopharyngeal sample with URTI symptoms without new pulmonary infiltrates. Lower respiratory tract infection (LRTI) was defined as detection of PIV in either upper or lower respiratory tract samples with new pulmonary infiltrates, with or without hypoxia. PIV-associated mortality was defined as death with respiratory failure and persistent LRTI within 90 days after diagnosis. The study included 143 adult patients. Of these, 55 (38%) progressed to or initially presented with LRTI. Among these, 22 (40%) died from PIV-associated mortality. An immunodeficiency risk score was developed from associated risk factors using a multivariable Cox regression model. Patients were stratified into low (0-2), moderate (3-5), and high risk (6-8) groups with PIV-associated mortalities of 0%, 9%, and 67%, respectively (p < 0.005, Harrell's C-index = 0.84). PIV infection can result in substantial mortality in patients with hematologic malignancy if it progresses to LRTI. The immunodeficiency risk score presented here may be useful for distinguishing moderate and high risk groups that might benefit from antiviral therapy.

Prevention of respiratory outbreaks in the rehabilitation setting

Background

Respiratory viral (RV) outbreaks in rehabilitation facilities can jeopardise patient safety, interfere with patient rehabilitation goals and cause unit closures that impede patient flow in referring facilities.

Problem

Despite education about infection prevention practices, frequent RV outbreaks were declared each year at our rehabilitation facility.

Methods

Before and after study design. The primary outcome was the number of bed closure days due to outbreak per overall bed days. Process measures included delays in initiation of transmission-based precautions, RV testing and reporting of staff to occupational health and safety (OHS). Balancing measures included the number of isolation days and staff missed work hours.

Interventions

Based on comprehensive analysis of prior outbreaks, the following changes were implemented: (1) clear criteria for initiation of transmission-based precautions, (2) communication to visitors to avoid visitation if infectious symptoms were present, (3) exemption of staff absences if documented due to infectious illness, (4) development of an electronic programme providing guidance to staff about whether they should be excluded from work due to infectious illness.

Results

The number of bed closure days due to outbreak per overall bed days dropped from 2.8% to 0.5% during the intervention season and sustained at 0.6% during the postintervention season (p<0.001). There were fewer delays in initiation of droplet and contact precautions (28.8% to 15.5%, p=0.005) and collection of RV testing (42.9% to 20.3%, p<0.001), better reporting to OHS (9 vs 28.8 reports per 100 employees; p<0.001) and fewer isolation days (7.8% vs 7.3%; p=0.02) without a significant increase in missed work hours per 100 hours worked (4.0 vs 3.9; p=0.12).

Conclusion

This Quality Improvement study highlights the process changes that can prevent respiratory outbreaks in the rehabilitation setting.

Refinement of estimates of mortality risk using the Radiologic Severity Index in hematologic malignancy patients with respiratory syncytial virus infection

BACKGROUND

Immunocompromised hematologic malignancy (HM) patients experience high mortality after respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI). We measured radiologic severity to determine whether it could improve the performance of 60-day mortality models based only upon immunodeficiency severity.

METHODS

We studied 155 HM patients, including 84 hematopoietic cell transplant recipients, who developed RSV LRTI from 2001 to 2013. We measured immunodeficiency using lymphopenia (lymphocyte count <200 cells/mm³ ), Immunodeficiency Severity Index (ISI), and Severe Immunodeficiency (SID) criteria. Radiologic severity was measured by the Radiologic Severity Index (RSI, range 0-72) at time of LRTI (baseline-RSI) and peak severity (peak-RSI). Delta-RSI was defined as the difference between baseline-RSI and peak-RSI. We used logistic regression models to measure the association of immunodeficiency and RSI with 60-day all-cause mortality, and measured model discrimination using areas under the receiver-operating characteristics curves, calibration using Brier scores, and explained variance using pseudo-R² values.

RESULTS

Forty-one patients died within 60 days of RSV LRTI. Severe immunodeficiency was associated with higher mortality. Peak-RSI (odds ratio [OR] 1.06/point, 95% confidence interval [CI] 1.04-1.08), and delta-RSI (OR 1.07/point, 95% CI 1.05-1.10) were associated with 60-day mortality after RSV LRTI, but not baseline-RSI. Addition of peak-RSI or delta-RSI to baseline immunodeficiency improved the discrimination, calibration, and explained variance (P < 0.001) of 60-day mortality models.

CONCLUSIONS

Although baseline immunodeficiency in HM patients helps predict 60-day mortality after RSV LRTI, mortality risk estimates can be further refined by also measuring LRTI progression using RSI. RSI is well-suited as a marker of LRTI severity in RSV infection.

[Prophylaxis of infections post-allogeneic transplantation: Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]

Allogeneic hematopoietic stem cell transplantation is a curative treatment for many hematological diseases. However, this procedure causes the patient to be susceptible to infection. Prophylactic treatments are administered in clinical practice even thought the level of evidence of their effectiveness is not always high. In addition, changes in the transplantation procedures - use of reduced intensity conditioning, development of alternative graft sources - must lead to a rethinking of attitudes towards prophylaxis. Our working group based its recommendations on a review of referential articles and publications on the subject found in the literature. These recommendations concern the prophylaxis of infections caused by HSV1, HSV2, varicella zoster, and hepatitis B, as well as anti-bacterial and digestive decontamination prophylaxis, prevention of pneumocystis, toxoplasmosis, tuberculosis, as well as prophylaxis of fungal infections. Other infectious agents usually involved in infections post-allotransplant have been the subject of another set of recommendations from the French Society of Bone Marrow Transplantation and Cellular Therapy.

Risk factors for mortality after respiratory syncytial virus lower respiratory tract infection in adults with hematologic malignancies

Background

Respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) is associated with high mortality in patients with hematologic malignancies (HM). We sought to determine whether allogeneic hematopoietic cell transplant (allo‐HCT) recipients would be at higher risk for 60‐day mortality.

Methods

We examined a retrospective cohort of adults with HM with or without HCT treated for RSV LRTI (n = 154) at our institution from 1996‐2013. We defined possible RSV LRTI as RSV detected only in the upper respiratory tract with new radiologic infiltrates and proven RSV LRTI as RSV detected in BAL fluid with new radiologic infiltrates. Immunodeficiency Scoring Index (ISI) and Severe Immunodeficiency (SID) criteria were calculated for HCT recipients. Multivariable logistic regression analyses were performed to identify independent risk factors associated with 60‐day all‐cause mortality.

Results

Mortality was high in HM patients (25%), but there was no difference between those without HCT, autologous or allo‐HCT recipients in logistic regression models. Separate multivariate models showed that at RSV diagnosis, neutropenia (OR 8.3, 95% CI 2.8‐24.2, P = 0.005) and lymphopenia (OR 3.7, 95% CI 1.7‐8.2, P = 0.001) were associated with 60‐day mortality. Proven LRTI was associated with higher 60‐day mortality (neutropenia model: OR 4.7, 95%CI 1.7‐13.5; lymphopenia model: OR 3.3, 95% CI 1.2‐8.8), and higher ICU admission. In HCT recipients, high ISI and very severe immunodeficiency by SID criteria were associated with higher 60‐day all‐cause mortality.

Conclusions

Mortality is similarly high among HM patients without HCT and HCT recipients. High‐grade immunodeficiency and detection of RSV from BAL fluid are associated with higher 60‐day mortality.

Unrecognised Outbreak: Human parainfluenza virus infections in a pediatric oncology unit. A new diagnostic PCR and virus monitoring system may allow early detection of future outbreaks

Background: Human parainfluenza viruses (HPIVs) are significant causes of both upper and lower respiratory tract infections with type 3 (HPIV3) causing the most severe disease in the immunocompromised cohorts.  The objective of this study was to analyse the epidemiological nature of a cluster of cases of HPIV3 in a pediatric oncology unit of a major teaching hospital. Methods: In order to determine whether the activity observed represented a deviation from the norm, seasonal trends of HPIV3 in the surrounding geographical area as well as on the ward in question were analysed.  The genetic link between cases was established by the phylogenetic analysis of the non-coding hypervariable region between the M (Matrix) and F (fusion) genes of HPIV3. The 15 cases involved and 15 unrelated cases were sequenced.  Transmission routes were subsequently inferred and visualized using Konstanz Information Miner (KNIME) 3.3.2. Results: Of the 15 cases identified, 14 were attributed to a point source outbreak. Two out of 14 outbreak cases were found to differ by a single mutation A182C. The outbreak strain was also seen in 1 out of 15 unrelated cases, indicating that it was introduced from the community. Transmission modeling was not able to link all the cases and establish a conclusive chain of transmission. No staff were tested during the outbreak period. No deaths occurred as a result of the outbreak. Conclusion: A point source outbreak of HPIV3 was recognized post factum on an oncology pediatric unit in a major teaching hospital. This raised concern about the possibility of a future more serious outbreak. Weaknesses in existing systems were identified and a new dedicated respiratory virus monitoring system introduced.  Pediatric oncology units require sophisticated systems for early identification of potentially life-threatening viral outbreaks.

A multifaceted approach to RSV vaccination

Respiratory Syncytial Virus (RSV) is the leading cause of pneumonia and bronchiolitis in infants, resulting in significant morbidity and mortality worldwide. In addition, RSV infections occur throughout different ages, thus, maintaining the virus in circulation, and increasing health risk to more susceptible populations such as infants, the elderly, and the immunocompromised. To date, there is no vaccine approved to prevent RSV infection or minimize symptoms of infection. Current clinical trials for vaccines against RSV are being carried out in four very different populations. There are vaccines that target two different pediatric populations, infants 2 to 6 month of age and seropositive children over 6 months of age, as well as women (non-pregnant or pregnant in their third trimester). There are vaccines that target adult and elderly populations. In this review, we will present and discuss RSV vaccine candidates currently in clinical trials. We will describe the preclinical studies instrumental for their advancement, with the goal of introducing new preclinical models that may more accurately predict the outcome of clinical vaccine studies.

A multicenter investigation of respiratory syncytial viral infection in children with hematopoietic cell transplantation

BACKGROUND

Hematopoietic cell transplant (HCT) may be a risk factor for morbidity and mortality from respiratory syncytial virus (RSV). Previous studies have been limited by small sample size. We took a multicenter approach with the goal of better understanding the epidemiology, risk factors, treatment, morbidity, and mortality associated with RSV infections among children with HCT in the United States.

METHODS

A retrospective, multicenter, cohort study of pediatric HCT recipients were diagnosed with RSV infection between January 2010 and December 2014.

RESULTS

Of the 1522 HCT, 47 (3%) patients were diagnosed with RSV. Of those with RSV, 9 (19.1%) were admitted to the pediatric intensive care unit (PICU), 6 (12.8%) received invasive mechanical ventilation, and 1 died. Prophylactic palivizumab was uncommon. All who required critical care received ribavirin vs 7.3% of those who did not (P = .004). Cobacterial infections were found in 16 patients and were not associated with the need for critical care. We examined potential risk factors for severity of RSV disease. In those who received invasive ventilation, 100% had one of the preidentified risk factors. Half of those requiring mechanical ventilation were diagnosed with RSV during their conditioning for transplant as opposed to only 2.4% of those that did not require invasive mechanical ventilation (P = .005).

CONCLUSIONS

In this multicenter cohort, RSV was not common in children following HCT. Few children infected with RSV required critical care and mortality was low. Those diagnosed with RSV during conditioning for transplant were at higher risk for invasive mechanical ventilation.

Pathogenicity and peramivir efficacy in immunocompromised murine models of influenza B virus infection

Influenza B viruses are important human pathogens that remain inadequately studied, largely because available animal models are poorly defined. Here, we developed an immunocompromised murine models for influenza B virus infection, which we subsequently used to study pathogenicity and to examine antiviral efficacy of the neuraminidase inhibitor peramivir. We studied three influenza B viruses that represent both the Yamagata (B/Massachusetts/2/2012 and B/Phuket/3073/2013) and Victoria (B/Brisbane/60/2008, BR/08) lineages. BR/08 was the most pathogenic in genetically modified immunocompromised mice [BALB scid and non-obese diabetic (NOD) scid strains] causing lethal infection without prior adaptation. The immunocompromised mice demonstrated prolonged virus shedding with modest induction of immune responses compared to BALB/c. Rather than severe virus burden, BR/08 virus-associated disease severity correlated with extensive virus spread and severe pulmonary pathology, stronger and persistent natural killer cell responses, and the extended induction of pro-inflammatory cytokines and chemokines. In contrast to a single-dose treatment (75 mg/kg/day), repeated doses of peramivir rescued BALB scid mice from lethal challenge with BR/08, but did not result in complete virus clearance. In summary, we have established immunocompromised murine models for influenza B virus infection that will facilitate evaluations of the efficacy of currently available and investigational anti-influenza drugs.

Viral Pneumonia in Patients with Hematologic Malignancy or Hematopoietic Stem Cell Transplantation

Viral pneumonias in patients with hematologic malignancies and recipients of hematopoietic stem cell transplantation cause significant morbidity and mortality. Advances in diagnostic techniques have enabled rapid identification of respiratory viral pathogens from upper and lower respiratory tract samples. Lymphopenia, myeloablative and T-cell depleting chemotherapy, graft-versus-host disease, and other factors increase the risk of developing life-threatening viral pneumonia. Chest imaging is often nonspecific but may aid in diagnoses. Bronchoscopy with bronchoalveolar lavage is recommended in those at high risk for viral pneumonia who have new infiltrates on chest imaging.

Respiratory Viral Infections and Coinfections in Children With Cancer, Fever and Neutropenia: Clinical Outcome of Infections Caused by Different Respiratory Viruses

BACKGROUND

Respiratory viral infections in episodes of fever and neutropenia (FN) in children with cancer are not well characterized. We compared the clinical outcome of infections caused by different respiratory viruses (RVs) and by RV coinfection in this population.

METHODS

Children with cancer and FN at 3 hospitals in Chile were prospectively evaluated by clinical examination, blood cultures and detection of 17 RVs using multiplex polymerase chain reaction (nasopharyngeal samples). Clinical characterization and outcome variables were determined and compared by the type of RV detected.

RESULTS

A total of 1044 episodes of FN in 525 children were included. At least 1 RV was detected in 46%. In 350 of 1044 (34%) episodes, we detected only RVs, of which 284 (81%) were classified as a single-RV infection and 66 (19%) as a viral coinfection. Respiratory symptoms were present at admission in 65% of the episodes with any detected RV. Median age was 6 years (interquartile range, 3-10), and 51% were women. The most common RVs detected were rhinovirus, respiratory syncytial virus, parainfluenza, influenza, adenovirus and human metapneumovirus. Episodes caused by different types of RVs had no differences in the clinical outcome (days of hospitalization, days of fever, O2 requirement, admission to the intensive care unit and death) and when comparing single and viral coinfection.

CONCLUSIONS

To our knowledge, this is the largest report comparing clinical outcome in FN episodes caused by different RVs in children with cancer. A positive polymerase chain reaction for RV at admission was significantly associated with the presence of respiratory symptoms. Our data showed a favorable outcome in all episodes with RV detection, including single and viral coinfections.

Respiratory Syncytial Virus and Human Metapneumovirus Infection in Transplant Recipients

Respiratory viral infections due to respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) cause infections in immunocompromised transplant patients ranging from mild upper respiratory infections to severe lower respiratory tract disease with respiratory failure. These viruses are more readily diagnosed due to improvements in sensitive molecular diagnostic methods. The epidemiology of RSV and hMPV is similarly becoming more readily appreciated in hematopoietic stem cell transplant (HSCT) patients of all ages as well as solid organ transplant (SOT) patients, with lung transplant recipients having evidence of more frequent and severe complications related to these viruses. RSV and hMPV infection typically but not always present with upper respiratory signs and symptoms that progress to lower respiratory tract disease. Treatment options for RSV are limited, with aerosolized, intravenous, and oral ribavirin all studied in HSCT and lung transplant patients. No antiviral therapy for the treatment of hMPV is available, although ribavirin has shown some effectiveness in vitro. New antiviral agents including RSV fusion inhibitors and nucleoside analogs are being developed, with some under clinical evaluation.

Rhinovirus, Coronavirus, Enterovirus, and Bocavirus After Hematopoietic Cell Transplantation or Solid Organ Transplantation

Respiratory viral infections represent a significant cause of morbidity and mortality in immunocompromised hosts. Newer molecular detection assays have allowed for the characterization of several respiratory viruses not previously recognized as having significant clinical impact in the immunocompromised population. Human rhinoviruses are the most common respiratory viruses detected in the upper respiratory tract of hematopoietic cell transplant and lung transplant recipients, and evidence on the impact on clinical outcomes is mounting. Other respiratory viruses including enteroviruses (EVs), coronaviruses (CoVs), and bocavirus may also contribute to pulmonary disease; however, data is limited in the immunocompromised population. Further studies are needed to define the epidemiology, risk factors, and clinical outcomes of these infections; this data will help inform decisions regarding development of antiviral therapy and infection prevention strategies.

Respiratory syncytial virus infections in pediatric transplant recipients: A Canadian Paediatric Surveillance Program study

The incidence and spectrum of severity of RSV infections in SOT or HSCT recipients is not known. From September 2010 through August 2013, pediatricians were surveyed monthly by the CPSP for SOT or HSCT recipients with RSV infection within two yr post-transplant. There were 24 completed case report forms that fit the inclusion criteria (10 HSCT and 14 SOT recipients). Six of 24 cases (25%) remained outpatients, and 11 (46%) were managed on an inpatient ward, while seven (29%) required intensive care of which five required mechanical ventilation and two died of RSV infection. Ten of 23 cases (43%) were nosocomial with these data not recorded for one case. Many transplant recipients recover uneventfully from RSV infection in the first two yr post-transplant. However, severe disease and death also occur. Larger studies are required to establish risk factors for poor outcomes. Prevention of nosocomial RSV should be a priority in transplant recipients.

Clinical disease due to enterovirus D68 in adult hematologic malignancy patients and hematopoietic cell transplant recipients

The United States Centers for Disease Control and Prevention reported over 1000 cases of severe respiratory disease in pediatric patients associated with enterovirus D68 (EV-D68) in the fall of 2014. We sought to identify and define the clinical burden of disease due to EV-D68 in adult patients with hematologic malignancy or undergoing hematopoietic cell transplant (HCT). Real-time reverse-transcriptase polymerase chain reaction (PCR) for EV-D68 was performed on all respiratory samples positive for human rhinovirus (HRV) or negative for all respiratory viruses by a laboratory-developed respiratory viral PCR panel from August 11, 2014, to November 7, 2014. Presumptive cases were defined as those with an EV-D68 PCR cycle threshold (CT) at least 4 cycles lower than the HRV CT for HRV-positive samples or any EV-D68 CT value for HRV-negative samples. Sequencing of a 150-bp fragment of the 5' noncoding region confirmed EV-D68 in 16 of 506 respiratory samples. Eight patients had a history of hematologic malignancy, and 6 of these had undergone HCT. Presentation ranged from mild upper respiratory symptoms to respiratory failure. EV-D68 can infect adult patients with hematologic malignancy and HCT recipients and may be associated with severe respiratory disease. Current commercial diagnostic assays cannot differentiate EV-D68 from other enteroviruses or HRV, and improved rapid diagnostic tools are needed.

Agents that increase AAM differentiation blunt RSV-mediated lung pathology

RSV is the most significant cause of serious lower respiratory tract infection in infants and young children worldwide. There is currently no vaccine for the virus, and antiviral therapy (e.g., ribavirin) has shown no efficacy against the disease. We reported that alternatively activated macrophages (AAMs) mediate resolution of RSV-induced pathology. AAM differentiation requires macrophage-derived IL-4 and -13, autocrine/paracrine signaling through the type I IL-4 receptor, and STAT6 activation. Based on these findings, we reasoned that it would be possible to intervene therapeutically in RSV disease by increasing AAM differentiation, thereby decreasing lung pathology. Mice treated with the IL-4/anti-IL-4 immune complexes, shown previously to sustain levels of circulating IL-4, increased the RSV-induced AAM markers arginase-1 and mannose receptor and decreased the lung pathology. Induction of PPARγ, shown to play a role in AAM development, by the PPARγ agonist rosiglitazone or treatment of mice with the macrolide antibiotic AZM, also reported to skew macrophage differentiation to an AAM phenotype, increased the AAM markers and mitigated RSV-induced lung pathology. Collectively, our data suggest that therapeutic manipulation of macrophage differentiation to enhance the AAM phenotype is a viable approach for ameliorating RSV-induced disease.

Clinical characteristics and outcomes of severe rhinovirus-associated pneumonia identified by bronchoscopic bronchoalveolar lavage in adults: comparison with severe influenza virus-associated pneumonia

BACKGROUND

Rhinoviruses (RVs) may cause pneumonia, but the characteristics of RV-associated pneumonia have not been adequately evaluated.

OBJECTIVE

We aimed to compare characteristics, complications, and outcomes between severe RV- and influenza virus (IFV)-associated pneumonia in adults.

STUDY DESIGN

We used prospective cohort data of adult patients with severe pneumonia who had been admitted to the medical intensive care unit of a tertiary care hospital over a 4-year period. The clinical features and outcomes of 27 patients with RV-positive bronchoscopic bronchoalveolar lavage (BAL) fluid were compared to those of 51 pneumonia patients with IFV-positive BAL fluid or IFV-positive nasopharyngeal specimens.

RESULTS

Of 356 patients who underwent bronchoscopic BAL and respiratory virus polymerase chain reaction (PCR), RV was the most commonly identified virus (8.1%) from BAL fluid. Patients with RV-associated pneumonia were more likely to be immunocompromised than patients with IFV-associated pneumonia (81.5% vs. 33.3%, p<0.001). Bacterial coinfection tended to be less common in the RV group (18.5% vs. 37.3%, p=0.09). Although septic shock was less common in the RV group (29.6% vs. 54.9%, p=0.03), other clinical manifestations, laboratory findings, and radiologic patterns were similar between the groups. The 28-day mortality of patients with severe RV- and IFV-associated pneumonia was similarly high (29.6% vs. 35.3% respectively, p=0.61).

CONCLUSIONS

Severe RV-associated pneumonia patients were more likely to be immunocompromised and less likely to present septic shock. Overall clinical features were similar and mortalities of both groups were comparably high. Studies of larger cohorts encompassing mild to moderate pneumonia patients are needed.

Acute respiratory viral infections in pediatric cancer patients undergoing chemotherapy

OBJECTIVE

to estimate the prevalence of infection by respiratory viruses in pediatric patients with cancer and acute respiratory infection (ARI) and/or fever.

METHODS

cross-sectional study, from January 2011 to December 2012. The secretions of nasopharyngeal aspirates were analyzed in children younger than 21 years with acute respiratory infections. Patients were treated at the Grupo em Defesa da Criança Com Câncer (Grendacc) and University Hospital (HU), Jundiaí, SP. The rapid test was used for detection of influenza virus (Kit Biotrin, Inc. Ireland), and real-time multiplex polymerase chain reaction (FTD, Respiratory pathogens, multiplex Fast Trade Kit, Malta) for detection of influenza virus (H1N1, B), rhinovirus, parainfluenza virus, adenovirus, respiratory syncytial virus, human parechovirus, bocavirus, metapneumovirus, and human coronavirus. The prevalence of viral infection was estimated and association tests were used (χ(2) or Fisher's exact test).

RESULTS

104 samples of nasopharyngeal aspirate and blood were analyzed. The median age was 12 ± 5.2 years, 51% males, 68% whites, 32% had repeated ARIs, 32% prior antibiotic use, 19.8% cough, and 8% contact with ARIs. A total of 94.3% were in good general status. Acute lymphocytic leukemia (42.3%) was the most prevalent neoplasia. Respiratory viruses were detected in 50 samples: rhinoviruses (23.1%), respiratory syncytial virus AB (8.7%), and coronavirus (6.8%). Co-detection occurred in 19% of cases with 2 viruses and in 3% of those with 3 viruses, and was more frequent between rhinovirus and coronavirus 43. Fever in neutropenic patients was observed in 13%, of which four (30.7) were positive for viruses. There were no deaths.

CONCLUSIONS

the prevalence of respiratory viruses was relevant in the infectious episode, with no increase in morbidity and mortality. Viral co-detection was frequent in patients with cancer and ARIs.

The FilmArray® respiratory panel: an automated, broadly multiplexed molecular test for the rapid and accurate detection of respiratory pathogens

The FilmArray Respiratory Panel (RP) (BioFire(™) Diagnostics, Inc., Salt Lake City, UT, USA) is the first multiplex molecular panel cleared by the US FDA for the detection of both bacterial and viral respiratory pathogens in nasopharygeal swabs. The FilmArray RP targets 20 pathogens including 17 viruses and subtypes and three bacteria, and is performed with minimal sample manipulation. The FilmArray RP has a fully automated sample-to-answer workflow with a turn-around-time of approximately 1 h. The reported sensitivity and specificity of the assay ranges from 80 to 100 and 100%, respectively, with the sensitivity for the adenovirus as low as 46%. A new version of the FilmArray RP assay (version 1.7) with improved sensitivity for the adenovirus was released in 2013. The performance characteristics and simplified workflow have allowed its implementation in a wide range of laboratories. The FilmArray RP has changed the diagnostic landscape and will have a significant impact on the care of patients with respiratory tract infection.

A recombinant anchorless respiratory syncytial virus (RSV) fusion (F) protein/monophosphoryl lipid A (MPL) vaccine protects against RSV-induced replication and lung pathology

We previously demonstrated that the severe cytokine storm and pathology associated with RSV infection following intramuscular vaccination of cotton rats with FI-RSV Lot 100 could be completely abolished by formulating the vaccine with the mild TLR4 agonist and adjuvant, monophosphoryl lipid A (MPL). Despite this significant improvement, the vaccine failed to blunt viral replication in the lungs. Since MPL is a weak TLR4 agonist, we hypothesized that its adjuvant activity was mediated by modulating the innate immune response of respiratory tract resident macrophages. Therefore, we developed a new vaccine preparation with purified, baculovirus expressed, partially purified, anchorless RSV F protein formulated with synthetic MPL that was administered to cotton rats intranasally, followed by an intradermal boost. This novel formulation and heterologous "prime/boost" route of administration resulted in decreased viral titers compared to that seen in animals vaccinated with F protein alone. Furthermore, animals vaccinated by this route showed no evidence of enhanced lung pathology upon RSV infection. This indicates that MPL acts as an immune modulator that protects the host from vaccine-enhanced pathology, and reduces RSV replication in the lower respiratory tract when administered by a heterologous prime/boost immunization regimen.

Advances in the management of viral infections

Viral infections are common in cancer patients. The risk and severity of infection are influenced by patient, disease, treatment, and viral factors. Severe viral infections are more likely to occur in treatment regimens that are more immunosuppressive. Historically, the most frequent severe infections have been due to herpesviruses, but more recently, other pathogens, especially community respiratory and hepatitis viruses, have received increasing attention as major viral pathogens in cancer patients. Because of the new diagnostic assays and the introduction of better therapeutic options, knowledge of viral infections is important in optimizing antineoplastic therapies.

Epidemiology of viral respiratory tract infections in an outpatient haematology facility

Viral respiratory tract infections (VRTI) are an important cause of morbidity and mortality in haematology patients, particularly after haematopoietic stem cell transplantation (HSCT). The incidence, clinical presentation and outcome of symptomatic and asymptomatic VRTI in HSCT outpatient unit were prospectively evaluated during a single influenza season (January–March 2011). Pharyngeal swabs were performed at the first visit and if new symptoms were present. Molecular multiplex assay for 12 respiratory viruses was performed by the regional reference laboratory. Among 264 swabs from 193 outpatients, 58 (22 %) resulted positive for 61 viruses (influenza, n = 20; respiratory syncytial virus [RSV], n = 21; rhinovirus, n = 12; coronavirus, n = 4; adenovirus, n = 3; parainfluenza, n = 1). VRTI were detected more frequently in the presence of symptoms than in asymptomatic patients: 49 out of 162 (30 %) vs. 9 out of 102 (9 %), p < 0.001. Influenza-like illness syndrome (ILI) was significantly associated with a VRTI if compared to other presentations (42 %), while the European Centre for Disease Prevention and Control definition was not (30 %). Positive predictive value (PPV) of ILI for influenza was 17 %. Influenza and RSV peak periods were contemporary. Influenza prophylaxis was given to 25 patients following exposure. Low rate of progression from upper to lower respiratory tract infection (approximately 5 % for influenza and RSV), no nosocomial epidemics and no VRTI-related deaths were observed. VRTI are very frequent in high-risk haematology outpatients, but symptoms are aspecific and PPV of ILI is low. Symptoms of influenza and RSV overlap. Thus, microbiological diagnosis and contact preventive measures are crucial. Rather than universal influenza prophylaxis, prompt diagnosis and treatment of only documented infections could be pursued.

Outcomes of hematopoietic SCT recipients with rhinovirus infection: a matched, case-control study

The impact of rhinovirus in hematopoietic SCT (HSCT) recipients is not well defined. A retrospective, matched, case–control study of HSCT recipients with rhinovirus was conducted between 2009 and 2011. Controls were matched for timing relative to transplant, malignancy, and stem cell source. There were 47 cases and 94 controls. The cases and controls did not differ with respect to age, gender, ethnicity, donor source, malignancy, conditioning regimen, immunosuppression, antimicrobial prophylaxis or significant comorbidities. There were no differences in need for intensive care unit care, 100 day mortality, hospice discharge, relapse of disease, GVHD or development of disease or infection due to CMV or EBV. Other infectious complications after rhinovirus diagnosis were also equal. However, there was an increased number of recurrent hospitalizations from any cause among the cases (46.8% vs 24.5%, P=0.007). Recurrent hospitalizations due to any infection were also more common in cases (34% vs 14.9%, P=0.015). For patients who were diagnosed with rhinovirus pre-transplant (n=13), there was no difference in outcome compared with matched controls. HSCT recipients with rhinovirus have an increased risk of hospital readmission. However, there was no difference in outcome compared with matched controls. Transplantation in patients with active rhinovirus infection appears to be safe.

Prophylactic and therapeutic testing of Nicotiana-derived RSV-neutralizing human monoclonal antibodies in the cotton rat model

Severe lower respiratory tract infection in infants and small children is commonly caused by respiratory syncytial virus (RSV). Palivizumab (Synagis(®)), a humanized IgG1 monoclonal antibody (mAb) approved for RSV immunoprophylaxis in at-risk neonates, is highly effective, but pharmacoeconomic analyses suggest its use may not be cost-effective. Previously described potent RSV neutralizers (human Fab R19 and F2-5; human IgG RF-1 and RF-2) were produced in IgG format in a rapid and inexpensive Nicotiana-based manufacturing system for comparison with palivizumab. Both plant-derived (palivizumab-N) and commercial palivizumab, which is produced in a mouse myeloma cell line, showed protection in prophylactic (p < 0.001 for both mAbs) and therapeutic protocols (p < 0.001 and p < 0.05 respectively). The additional plant-derived human mAbs directed against alternative epitopes displayed neutralizing activity, but conferred less protection in vivo than palivizumab-N or palivizumab. Palivizumab remains one of the most efficacious RSV mAbs described to date. Production in plants may reduce manufacturing costs and improve the pharmacoeconomics of RSV immunoprophylaxis and therapy.

Delayed RSV diagnosis in a stem cell transplant population due to mutations that result in negative polymerase chain reaction

Respiratory syncytial virus (RSV) is a serious cause of morbidity and mortality in the adult hematopoietic stem cell transplant (HSCT) population. The timely diagnosis of RSV infection in this population is important for initiating therapy and instituting appropriate infection prevention measures. Molecular multiplex assays now offer increased sensitivity for a more accurate diagnosis. This study presents 5 cases of RSV infection in HSCT patients in which diagnosis was delayed due to false-negative results from a multiplex polymerase chain reaction (PCR) assay. The false-negative result was due to a single base-pair mutation in the RSV strain. These false results delayed the appropriate treatment of patients. This study shows that a combination of a multiplex PCR assay, viral antigen, and/or culture should be used to detect variants of RSV in patients and that multiplex respiratory viral assays should develop a more robust design that includes multiple genetic target per virus to prevent missing viruses that continue to have genetic variances.

Clinical relevance of natural killer cells following hematopoietic stem cell transplantation

Natural killer (NK) cells are one of the first cells to recover following allogeneic hematopoietic stem cell transplantation (HSCT), and are believed to play an important role in facilitating engraftment or preventing post-transplant infection and tumor recurrence. Recent studies have provided novel insights into the mechanisms by which NK cells mediate these highly clinically relevant immunological functions. In particular, the ability of NK cells to reduce the risk of graft versus host disease (GVHD) and increase the graft versus leukemia effect (GVL) in the setting of human leukocyte antigen (HLA)-haploidentical HSCT highlights their clinical potentials. NK cells also mediate anti-viral protection, in particular against cytomegalovirus (CMV), an infection that causes significant morbidity and mortality following transplant. Another crucial function of NK cells is providing protection against bacterial infections at the mucosal barriers. NK cells achieve this by promoting anti-microbial defenses and regeneration of epithelial cells. These recent exciting findings provide a strong basis for the formulation of novel NK cell-based immunotherapies. In this review, we summarize the recent advances related to the mechanisms, functions, and future clinical prospects of NK cells that can impact post-transplant outcomes.

(S)-N-(2,5-Dimethylphenyl)-1-(quinoline-8-ylsulfonyl)pyrrolidine-2-carboxamide as a small molecule inhibitor probe for the study of respiratory syncytial virus infection

A high-throughput, cell-based screen was used to identify chemotypes as inhibitors for human respiratory syncytial virus (hRSV). Optimization of a sulfonylpyrrolidine scaffold resulted in compound 5o that inhibited a virus-induced cytopathic effect in the entry stage of infection (EC₅₀ = 2.3 ± 0.8 μM) with marginal cytotoxicity (CC₅₀ = 30.9 ± 1.1 μM) and reduced viral titer by 100-fold. Compared to ribavirin, sulfonylpyrrolidine 5o demonstrated an improved in vitro potency and selectivity index.

A randomized trial of one versus two doses of influenza vaccine after allogeneic transplantation

Influenza infection after allogeneic hematopoietic cell transplantation (allo-HCT) can result in severe complications. The effectiveness of the annual vaccine depends on age, immune competence, and the antigenic potential of the 3 strains included. We hypothesized that a second vaccine dose, the standard of care for vaccine-naïve children, might improve post hematopoietic cell transplantation (HCT) immune responses. Patients >60 days post-HCT were randomized to receive either 1 (n = 33) or 2 (n = 32) influenza vaccine doses separated by 1 month. The primary endpoint was whether 2 vaccinations induced superior immunity; however, we found no difference. Secondary endpoints were to identify variables associated with responses. Both hemagglutination inhibition (HI; P < .005) and ELISpot responses (P = .03) were greater for patients vaccinated ≥ 1 year posttransplantation. Umbilical cord blood (UCB) recipients showed less IFN-γ responses (P < .001). Interestingly, there was a positive correlation between the total number of CD19(+) cells before vaccination and seroconversion (P = .01) and an inverse correlation for IFN-γ responses (P = .05). Variables not associated with vaccine responses included prevaccine CD4(+) cell counts (total, naïve, or memory), steroid usage at vaccination, age, or conditioning intensity. Time from transplantation to vaccination and absolute CD19(+) cell counts were the strongest predictors of vaccine responses. Methods to improve influenza vaccine responses after allo-HCT are needed.

Molecular detection of respiratory viruses in immunocopromised ICU patients: incidence and meaning

Purpose

Prospective single-center study to assess the sensitivity and clinical relevance of molecular testing for respiratory viruses in critically ill immunocompromised patients with acute respiratory failure (ARF).

Methods

100 consecutive critically ill immunocompromised patients with ARF in 2007–2009. Among them, 65 had hematologic malignancies (including 14 hematopoietic stem cell transplant recipients), 22 had iatrogenic immunosuppression, and 13 had solid malignancies. A multiplex molecular assay (MMA) was added to the usual battery of tests performed to look for causes of ARF.

Results

Nasopharyngeal aspirates and/or bronchoalveolar lavage fluid were tested for respiratory viruses using both the MMA and immunofluorescence. A virus was detected in 47 (47%) patients using the MMA and 8 (8%) patients using immunofluorescence (P = 0.006). MMA-positive and MMA-negative patients had similar clinical and radiographic presentations and were not significantly different for the use of ventilatory support (58% vs. 76%, P = 0.09), occurrence of shock (43% vs. 53%, P = 0.41), use of renal replacement therapy (26% vs. 23%, P = 0.92), SAPS II (35 [26–44] vs. 38 [27–50], P = 0.36), time spent in the ICU (6 vs. 7 days, P = 0.35), or ICU mortality (17% vs. 28%, P = 0.27). Using MMA, a virus was found in 6 of the 12 patients with no diagnosis at the end of the etiologic investigations.

Conclusions

In critically ill immunocompromised patients, an MMA was far more sensitive than immunofluorescence for respiratory virus detection. Patients with RVs detected in the respiratory tract had the same clinical characteristics and outcomes as other patients.

Comparison of the Luminex xTAG RVP Fast assay and the Idaho Technology FilmArray RP assay for detection of respiratory viruses in pediatric patients at a cancer hospital

Respiratory viruses are increasingly recognized as serious causes of morbidity and mortality in immunocompromised patients. The rapid and sensitive detection of respiratory viruses is essential for the early diagnosis and administration of appropriate antiviral therapy, as well as for the effective implementation of infection control measures. We compared the performance of two commercial assays, xTAG RVP Fast (Luminex Diagnostics, Toronto, Canada) and FilmArray RVP (FA RVP; Idaho Technology, Salt Lake City, UT), in pediatric patients at Memorial Sloan-Kettering Cancer Center. These assays detect the following viruses: respiratory syncytial virus; influenza A and B viruses; parainfluenza viruses 1, 2, 3, and 4; human metapneumovirus; adenovirus; enterovirus-rhinovirus; coronaviruses NL63, HKU1, 229E, and OC43; and bocavirus. We tested a total of 358 respiratory specimens from 173 pediatric patients previously tested by direct fluorescence assay (DFA) and viral culture. The overall detection rate (number of positive specimens/total specimens) for viruses tested by all methods was 24% for DFA/culture, 45% for xTAG RVP Fast, and 51% for FA RVP. The agreement between the two multiplex assays was 84.5%, and the difference in detection rate was statistically significant (P < 0.0001). Overall, the FA RVP assay was more sensitive than the xTAG RVP Fast assay and had a turnaround time of approximately 1 h. The sensitivity, simplicity, and random-access platform make FA RVP an excellent choice for laboratory on-demand service with low to medium volume.

Prophylaxis and treatment of respiratory syncytial virus in adult immunocompromised patients

OBJECTIVE

To review the literature regarding current strategies and strategies under active development for the prevention and treatment of respiratory syncytial virus (RSV) infections in immunocompromised adults.

DATA SOURCES

The MEDLINE/PubMed, EMBASE, and Cochrane databases were queried from January 1980 to December 2011 for articles in English using these associated search terms: respiratory syncytial virus, ribavirin, intravenous immunoglobulin, IVIG, palivizumab, motavizumab, lung, pneumonia, transplantation, bone marrow, cancer, malignancy, and vaccine.

STUDY SELECTION AND DATA EXTRACTION

All relevant original studies, meta-analyses, systematic reviews, and review articles were assessed for inclusion. References from pertinent articles were examined for additional content not found during the initial search.

DATA SYNTHESIS

RSV in the immunocompromised adult can lead to significant morbidity and mortality. Treatment of RSV-infected adults is limited to antiviral therapy with ribavirin (aerosolized, oral, intravenous) and immunomodulation with intravenous immunoglobulins, corticosteroids, and palivizumab. Existing literature is predominantly case reports, small trials, and retrospective reviews of patients infected with RSV who have undergone lung or hematopoietic stem cell transplantation (HSCT). Palivizumab may be a viable option for prophylaxis against RSV in high-risk adults. Ribavirin is the most studied treatment option and should remain the backbone of multidrug regimens. Of the routes of administration, aerosolized ribavirin carries the preponderance of evidence and, though challenging, is preferred to limit systemic toxicities in the infected patient. Addition of an immunomodulator to ribavirin may provide a survival benefit over ribavirin alone; however, this has only been studied in a subset of HSCT patients with lower respiratory tract RSV infection.

CONCLUSIONS

Research most strongly supports the use of aerosolized ribavirin as the treatment strategy for immunocompromised adults with RSV. Addition of an immunomodulator may provide a survival benefit over ribavirin alone. Strategies and supportive data for the prevention of RSV infection in the high-risk adult are critically needed.

The Prophylaxis and Treatment with Antiviral Agents of Respiratory Syncytial Virus Infections

In this review, we consider recent advances in the discovery and development of antiviral agents for respiratory syncytial virus (RSV) infections. A background to the various manifestations of human RSV infection and current treatments is provided. The technical, clinical and commercial issues surrounding the development of such antiviral agents are discussed.

Respiratory viral infections in hematopoietic stem cell and solid organ transplant recipients

Respiratory viral infections (RVIs) are common causes of mild illness in immunocompetent children and adults with rare occurrences of significant morbidity or mortality. Complications are more common in the very young, very old, and those with underlying lung diseases. However, RVIs are increasingly recognized as a cause of morbidity and mortality in recipients of hematopoietic stem cell transplants (HSCT) and solid organ transplants (SOTs). Diagnostic techniques for respiratory syncytial virus (RSV), parainfluenza, influenza, and adenovirus have been clinically available for decades, and these infections are known to cause serious disease in transplant recipients. Modern molecular technology has now made it possible to detect other RVIs including human metapneumovirus, coronavirus, and bocavirus, and the role of these viruses in causing serious disease in transplant recipients is still being worked out. This article reviews the current information regarding epidemiology, pathogenesis, clinical presentation, diagnosis, and treatment of these infections, as well as the aspects of clinical significance of RVIs unique to HSCT or SOT.

Hematopoietic stem cell transplantation: an overview of infection risks and epidemiology

Hematopoietic stem cell transplantation (HSCT) is a treatment for multiple medical conditions that result in bone marrow failure and as an antineoplastic adoptive immunotherapy for hematologic malignancies. HSCT is associated with profound compromises in host barriers and all arms of innate and acquired immunity. The degree of immune compromise varies by type of transplant and over time. Immune reconstitution occurs within several months after autologous HSCT but takes up to a year or longer after allogeneic HSCT. In those patients who develop chronic graft-versus-host disease, immune reconstitution may take years or may never completely develop. Over time, with strengthening immune reconstitution and control of graft-versus-host disease, the risk for infection dissipates.

Management of RSV infections in adult recipients of hematopoietic stem cell transplantation

Respiratory syncytial virus (RSV) is a common cause of seasonal respiratory viral infection in patients who have undergone hematopoietic stem cell transplantation. RSV usually presents as an upper respiratory tract infection in this patient population but may progress rapidly to lower respiratory tract infection. Available therapies that have been used for the treatment of RSV infections are limited to ribavirin, intravenous immunoglobulin, and palivizumab. The use of aerosolized ribavirin, alone or in combination with either palivizumab or intravenous immunoglobulin, remains controversial. In this comprehensive review, we present and discuss the available literature on management of RSV infections in adult hematopoietic stem cell transplantation recipients with a focus on therapeutic modalities and outcomes.

Seroprotective titers against 2009 H1N1 influenza A virus after vaccination in allogeneic hematopoietic stem cell transplantation recipients

Little data are available regarding the safety and immunologic response to pandemic H1N1 influenza vaccine in recipients of allogeneic hematopoietic stem cell transplantation (HSCT). We measured serum antibody titers against A/California/7/2009 H1N1 using a hemagglutination inhibition assay in 82 allogeneic HSCT recipients who received the 2009 H1N1 vaccine between November 2009 and January 2010 after it became available at our institution. The median time between HSCT and vaccination was 19 months (range, 2.5-94 months), and the median time from vaccination to specimen collection was 56 days (range, 14-140 days). Seroprotective antibody titers (hemagglutination inhibition titer ≥1:40) against 2009 H1N1 influenza A virus were detected in 51% of patients. The presence of chronic graft-versus-host disease and type of conditioning regimen did not affect the rate of detection of seroprotective titers after vaccination. Patients were more likely to have a seroprotective titer the farther away from HSCT they were (adjusted odds ratio, 1.79 per year; 95% confidence interval, 1.12-2.85). Rituximab administration in the year before vaccination was associated with a lack of seroprotective titer (adjusted odds ratio, 0.11; 95% confidence interval, 0.01-0.97). The vaccine was safe and well tolerated. Strategies are needed to improve the influenza vaccine response in this population, especially those receiving immunotherapy.

Epidemiology of Acute Respiratory Failure in Patients with HM (ICU Only)

Pulmonary complications are common in hematological patients, particularly those receiving a hematological stem cell transplant (HSCT), and a significant percentage of them will require intensive care unit (ICU) admission. Acute respiratory failure in these patients is a threatening event, with a very poor outcome, particularly when mechanical ventilation (MV) is required. For many years, oncologists and intensivists had a pessimistic vision of the dismal outcome of those hematological patients requiring admission to the ICU. The bleak experience in this population led some authors to suggest early withdrawal of support, or even withholding the option of mechanical ventilation altogether. However, over the last years this vision seems to be changing. Great progress has been made in stem cell transplantation that can be ascribed to a better understanding of the human leukocyte antigen (HLA) system for donor selection, more effective and less toxic immunosupression for prevention and treatment of graft-versus host disease (GVHD), and significant advances in infectious disease therapy. Also improvements in ventilatory and supportive care, such as the early implantation of noninvasive ventilation (NIV), may avoid intubation in a significant percentage of patients suffering from acute respiratory failure. As a result of all this, the proportion of both hematological patients requiring management in the ICU and those requiring MV is decreasing. Also the survival rate of HSCT recipients admitted to the ICU has been steadily improving. In this chapter we will report on the epidemiology of acute respiratory failure in patients with hematological malignancies.

Infections in pediatric transplant recipients: not just small adults

Transplantation increasingly is being used as treatment for children with end-stage organ diseases, hematopoietic rescue from therapy used to treat malignancies, and as cure for primary immune deficiencies. This article reviews some of the major concepts regarding infections that complicate pediatric transplantation, highlighting differences in epidemiology, evaluation, treatment and prevention for children compared with adult recipients.

Hematopoietic stem cell transplantation: an overview of infection risks and epidemiology

Hematopoietic stem cell transplantation (HSCT) is a treatment for multiple medical conditions that result in bone marrow failure and as an antineoplastic adoptive immunotherapy for hematologic malignancies. HSCT is associated with profound compromises in host barriers and all arms of innate and acquired immunity. The degree of immune compromise varies by type of transplant and over time. Immune reconstitution occurs within several months after autologous HSCT but takes up to a year or longer after allogeneic HSCT. In those patients who develop chronic graft-versus-host disease, immune reconstitution may take years or may never completely develop. Over time, with strengthening immune reconstitution and control of graft-versus-host disease, the risk for infection dissipates.

New insights for development of a safe and protective RSV vaccine

Respiratory Syncytial Virus (RSV) is the leading cause of pneumonia and bronchiolitis in infants and children <1 year old, resulting in significant morbidity and mortality worldwide. There is currently no RSV vaccine. In the 1960s, a formalin-inactivated RSV (FI-RSV) vaccine trial led to exacerbated disease upon natural infection of vaccinees, including two deaths. The causes involved in the disastrous results of these vaccine trials are still unclear but they remain the engine for searching new avenues to develop a safe vaccine that can provide long-term protection against this important pathogen. This article reviews some of the early history of RSV vaccine development,as well as more recent information on the interaction between RSV and the host innate and adaptive immune responses. A safe and efficacious vaccine for RSV will require "re-education" of the host immune response against RSV to prevent vaccine-enhanced or severe RSV disease.