Respiratory syncytial virus infection in 406 hospitalized premature infants: results from a prospective German multicentre database

Improvement in Palivizumab Administration Prior to Discharge for Hospitalized Infants with Hemodynamically Significant Congenital Heart Disease: A Quality Improvement Initiative

In this quality improvement initiative, we aimed to increase provider adherence with palivizumab administration guidelines for hospitalized infants with hemodynamically significant congenital heart disease. We included 470 infants over four respiratory syncytial virus (RSV) seasons from 11/2017 to 03/2021 (baseline season: 11/2017-03/2018). Interventions included the following: education, including palivizumab in the sign-out template, identifying a pharmacy expert, and a text alert (seasons 1 and 2: 11/2018-03/2020) that was replaced by an electronic health record (EHR) best practice alert (BPA) in season 3 (11/2020-03/2021). The text alert and BPA prompted providers to add "Need for RSV immunoprophylaxis" to the EHR problem list. The outcome metric was the percentage of eligible patients administered palivizumab prior to discharge. The process metric was the percentage of eligible patients with "Need for RSV immunoprophylaxis" on the EHR problem list. The balancing metric was the percentage of palivizumab doses administered to ineligible patients. A statistical process control P-chart was used to analyze the outcome metric. The mean percentage of eligible patients who received palivizumab prior to hospital discharge increased significantly from 70.1% (82/117) to 90.0% (86/96) in season 1 and to 97.9% (140/143) in season 3. Palivizumab guideline adherence was as high or higher for those with "Need for RSV immunoprophylaxis" on the problem list than for those without it in most time periods. The percentage of inappropriate palivizumab doses decreased from 5.7% (n = 5) at baseline to 4.4% (n = 4) in season 1 and 0.0% (n = 0) in season 3. Through this initiative, we improved adherence with palivizumab administration guidelines for eligible infants prior to hospital discharge.

Burden of respiratory syncytial virus (RSV) infection in Germany: a systematic review

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of acute lower respiratory infection and hospitalizations among infants, young children, and the elderly. This systematic literature review aimed to summarize the epidemiological and economic burden estimates of RSV infection at any age in Germany.

METHODS

We conducted a systematic literature search to identify full-text articles published from 2003 to 2023 and reporting data on the epidemiological or economic burden of RSV in Germany. Based on pre-specified eligibility criteria, data on incidence, rates of hospital and intensive care unit (ICU) admission, clinical manifestation, underlying conditions, seasonality, health care resource use and costs were extracted.

RESULTS

After screening 315 full-text articles, we included 42 articles in the review. The characteristics of the included studies were heterogenous regarding study population, setting, age groups and RSV-related outcome measures. The most frequently reported epidemiological outcome measures were RSV detection rate (n = 33), followed by clinical manifestation (n = 19), seasonality (n = 18), and underlying conditions of RSV infection (n = 13). RSV detection rates were reported across heterogenous study populations, ranging from 5.2 to 55.4% in pediatric inpatient cases and from 2.9 to 14% in adult inpatient cases. All articles that reported RSV detection rates across several age groups demonstrated the highest burden in infants and young children. Few articles reported RSV-related outcome measures distinctively for the outpatient setting. Health care resource use, such as hospital length of stay, ICU admission rate and treatment of patients with RSV infection were described in 23 articles, of which only one study quantified associated costs from 1999 to 2003 for children ≤ 3 years. In-hospital ICU admission rates varied between 3.6 and 45%, depending on population characteristics as age and underlying conditions.

CONCLUSIONS

This systematic review revealed that RSV imposes substantial disease burden in infants, young children, and the elderly in Germany, whereby infants are particularly affected. To date, there has been limited exploration of the impact of RSV infection on healthy children or the elderly in Germany. Given their notably high reported burden in studies, the medical and economic RSV burden in these groups should move more into focus.

Occurrence of Central Nervous System Complications of Respiratory Syncytial Virus Infections: A Systematic Review with Meta-Analysis

An increasing base of evidence suggests that respiratory syncytial virus (RSV) infections may be associated with neurological complications. In accord with the PRISMA statement, we performed a systematic review and meta-analysis on the occurrence of encephalitis and encephalopathy associated with documented RSV infections. PubMed, Embase, and Scopus databases were searched for eligible observational studies published up to 10 April 2024. Raw data included the occurrence of RSV infections among cases of encephalitis and/or encephalopathy and cases of encephalitis and/or encephalopathy among series of RSV infections. Data were pooled in a random effects model. Case reports were also collected, and their data pooled as a cumulative series. Heterogeneity was assessed using the I2 measure, while reporting bias was assessed by means of funnel plots and regression analysis. A total of 15 studies for a total of 7719 RSV infections and 1631 cases of encephalitis were analyzed. Moreover, 27 case reports and case series were retrieved, for a total of 84 individual cases of encephalitis/encephalopathy occurring during a documented RSV infection. A pooled prevalence of 2.20 cases of encephalitis/encephalopathy per 100 RSV cases (I2 = 99%) was calculated, while a prevalence of RSV infections among cases of encephalitis/encephalopathy was estimated to 3.53 per 100 cases for studies on respiratory specimens (I2 = 48%) and 0.37 per cases on central nervous system (CNS) specimens (I2 = 0%). Detection of RSV within the CNS was relatively rare (17.86% of pooled case reports), being associated with male gender (adjusted odds ratio [aOR] 5.021, 95% confidence interval [95%CI] 1.104 to 22.831) and recovery with long-term sequelae (aOR 5.699, 95%CI 1.152; 28.183). Case fatality ratio was estimated to be 0.43 per 100 cases on observational studies and 10.71% in case reports, a difference likely due to publication bias. In summary, RSV represented a not frequent but notable cause of encephalitis/encephalopathy in adults and children. The paucity of available studies not only recommends a cautious appraisal of our results but stresses the clinical significance of future studies on incident cases of encephalitis and/or encephalopathy.

Inpatient Rsv-Management 2016-2022: Epidemiology and Adherence to A Bronchiolitis Treatment Standard at a German University Children's Hospital

BACKGROUND

This study analyzes the RSV season 2021/2022 in a referral children's hospital, compares the epidemiology and illness severity with RSV-infected inpatients from 2016 to 2020 and audits the adherence to our internal therapy standard for RSV bronchiolitis.

MATERIAL AND METHODS

Inpatients with rtPCR-confirmed RSV infection (Jan. 2016 to Jan. 2022).

RESULTS

The audit comprises 306 RSV inpatients, on average 50 hospitalizations per year; in 03/2020, a rapid RSV Season-Offset was observed. In the winter season 2020/2021, no patient with RSV was hospitalized. Beginning in July, we noticed a rapid increase of RSV-admissions (most cases in Sept./Oct, duration until Dec. 2021; n=53). In 2021-2022, a significant larger share needed PICU admission (9.4% vs 3.2%, p=0.040). Adherence to the internal guidance was low; only 11.8% (n=36) of all patients received supportive treatment without inhalative or systemic medications, 37% of all patients received antibiotics.

CONCLUSIONS

This audit confirms the strong impact of public preventive measures directed against SARS-CoV-2 transmission on RSV epidemiology. Few weeks after easing public COVID-19 restrictions (summer 2021), RSV inpatient cases rapidly increased, lasting until Dec. 2021. The audit of bronchiolitis management revealed surprisingly low adherence to the internal guidance, despite a face-to-face educational session with the attending pediatricians in Oct. 2021. Low adherence resulted in an unnecessary exposure of RSV patients to systemic medications of questionable benefit including antibiotics.

Respiratory Syncytial Virus Infection and Apnea Risk As Criteria for Hospitalization in Full Term Healthy Infants

Introduction Apnea is recognized as a serious and potentially life-threatening complication associated with Respiratory Syncope Virus (RSV). The literature reports a wide range of apnea rates for infants with comorbid factors. Prematurity and young chronological age have been historically associated with the risk of apnea in hospitalized infants. Few studies have specifically examined the risk of apnea in healthy infants presenting to the emergency department. Methods This is a retrospective review of infants diagnosed with RSV using a PCR assay. Patients were divided into "mild" and "severe" cohorts based on symptoms at presentation. This study occurred in the NYU Langone Long Island (NYULI) pediatric emergency department (ED), a midsize academic hospital in the Northeast United States. The study included infants <6 months of age, born full term without comorbid conditions such as chronic lung or cardiac conditions, seen in NYULI ED over three consecutive RSV seasons (2017-2020). The primary outcome was the risk of apneic events. Secondary outcomes included hospital admission, ICU admission, length of stay, and supplemental oxygen support. Results The risk of apnea was <2%, regardless of disease severity. There were no significant differences in demographics between mild and severe disease. Cohorts differed significantly in the number of hospitalizations (41 milds vs. 132 severe), ICU admissions (2 milds vs. 27 severe), need for oxygen support (17 milds vs. 92 severe), hospital readmissions (2 milds vs. 42 severe), and length of stay (2 days milds vs. 3 days severe). Conclusions Apnea does not pose a significant risk for healthy full-term infants with RSV disease of any severity. The decision to admit this population to the hospital should be based on clinical presentation and not solely on the perceived risk of apnea.

Respiratory Syncytial Virus: An Uncommon Cause of Febrile Seizures-Results from a Systematic Review and Meta-Analysis

Human Respiratory Syncytial Virus (RSV) is a highly contagious viral pathogen. In infants, it is usually listed among the main causes of medical referrals and hospitalizations, particularly among newborns, and a considerable base of evidence associates RSV infections and bronchiolitis with long-term neurological sequelae. We specifically performed a systematic review and meta-analysis in order to ascertain whether RSV infections may be associated with an increased risk for febrile seizures (FS) in infected infants. According to the PRISMA statement, Pubmed, Embase, and pre-print archive medRxiv.og were searched for eligible observational studies published up to 1 July 2022. Raw data included the incidence of FS among children admitted for influenza-like illness (ILI) and/or bronchiolitis, with a confirmed diagnosis of RSV or seasonal influenza virus (SIV) infection. Data were then pooled in a random-effects model. Heterogeneity was assessed using the I² measure, while reporting bias was assessed by means of funnel plots and regression analysis. A total of 11 studies including 6847 cases of RSV infections were retrieved, with a pooled prevalence of 29.975 cases of FS per 1000 RSV cases (I² = 88.5%). The prevalence was not substantially greater in studies performed in pediatric intensive care units (53.817 per 1000 RSV cases vs. 23.552, p = 0.12). Higher occurrence of FS was reported from studies performed after 2010 (Risk Ratio [RR] 1.429, 95% Confidence Interval [95%CI] 1.049-1.948), and in China (RR 2.105, 95%CI 1.356-3.266) and South Africa (RR 1.722, 95%CI 1.060-2.824) than in Europe, while a lower occurrence was reported form the USA (RR 0.414, 95%CI 0.265-0.649). Eventually, FS were less likely reported from RSV cases compared to subjects affected by seasonal influenza (RR 0.402; 95%CI 0.228-0.708). Although RSV is often associated with high risk of neurological complications, substantially less cases of FS are reported than in SIV infections. However, the paucity of available studies recommends a cautious appraisal of aforementioned results.

Molecular epidemiology of respiratory syncytial virus in hospitalised children in Heidelberg, Southern Germany, 2014-2017

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of hopitalisation in young children with respiratory tract infections (RTI). The aim of this research project was to analyse RSV genotypes and the diversification of RSV strains among hospitalised children in Heidelberg, Germany.

METHODS

We prospectively analysed nasopharyngeal swabs (NPS) from children who were hospitalised with acute RTI at the University Hospital Heidelberg, Germany, during winter seasons 2014 to 2017. RSV RT-PCR and RSV sequence analysis of the G gene coding for the attachment glycoprotein were performed. Clinical data was obtained using a standardised questionnaire.

RESULTS

RSV was detected in 405 out of 946 samples from hospitalised children. Most RSV positive children were below the age of two years (84.4%) and had a lower RTI (78.8%). The majority of RSV positive children was male, significantly younger than RSV negative children with a median age of 0.39 years and with more severe respiratory symptoms. Out of 405 positive samples, 317 RSV strains were successfully sub-grouped into RSV subtypes A (57.4%; 182/317) and B (42.6%; 135/317). Both RSV subtypes cocirculated in all analysed winter seasons. Phylogenetic analysis of 317 isolates revealed that the majority of RSV-A strains (180/182) belonged to the ON1 genotype, most RSV-B strains could be attributed to the BAIX genotype (132/135). ON1 and BAIX strains showed a sub-differentiation into different lineages and we were able to identify new (sub)genotypes.

CONCLUSION

Analysis of the molecular epidemiology of RSV from different seasons revealed the cocirculation and diversification of RSV genotypes ON1 and BAIX.

Risk factors for RSV associated acute lower respiratory infection poor outcome and mortality in young children: A systematic review and meta-analysis

Respiratory syncytial virus associated acute lower respiratory infection (RSV-ALRI) constitutes a substantial disease burden in young children. We aimed to identify all studies investigating the risk factors of RSV-ALRI poor outcome or mortality in young children.We carried out a systematic literature review across 7 databases with data from studies published from January 1995 to December 2019. We defined poor outcome as need for prolonged hospital stay, oxygen supplementation, mechanical ventilation or intensive care unit (ICU) admission. Quality of all eligible studies was assessed according to modified GRADE criteria. We conducted meta-analyses to estimate odds ratio (OR) with 95% confidence intervals (CI) for individual risk factors. We identified 27 eligible studies, which investigated 20 risk factors for RSV-ALRI poor outcome and/or mortality in children younger than 5 years old, in comparison to those with RSV-ALRI who did not have poor outcome or mortality. Among those risk factors, 6 had statistically significant associations with RSV-ALRI poor outcome: any comorbidity (OR 2.69 (95% CI 1.89-3.83)), congenital heart disease (3.40 (95% CI 2.14-5.40)), prematurity with gestational age (GA) <37 weeks (1.75 (95% CI 1.31-2.36)), prematurity with GA ≤32 weeks (2.68 (95% CI 1.43-5.04)), age <3 months (4.91 (95% CI 1.64-14.71)), age <6 months (2.02 (95% CI 1.73-2.35)). Apart from age <3 months, the meta-estimate ORs for all other risk factors were based on studies using multivariable analysis. For mortality, only prematurity with GA <37 weeks had a significant meta-estimate of OR 3.81 (95% CI 1.68-8.63) based on univariable analysis.This study represents a comprehensive report of the association between various risk factors and RSV-ALRI poor outcome and mortality in young children. More research should be carried out to elucidate risk factors associated with poor outcome and mortality using multivariable analysis.

ELAC2, an Enzyme for tRNA Maturation, Plays a Role in the Cleavage of a Mature tRNA to Produce a tRNA-Derived RNA Fragment During Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infection in young children. However, effective treatment against RSV is unavailable. tRNA-derived RNA fragments (tRFs) are a recently discovered family of non-coding RNAs. We made an early observation that RSV infection causes significant induction of tRFs, which are mainly derived from the 5’-end of mature tRNAs (tRF5). However, their functions and biogenesis mechanism are not fully understood. Herein, we identified an enzyme responsible for the induction of a functional tRF5 derived from tRNA-Gln-CTG (tRF5-GlnCTG). We found that tRF5-GlnCTG promotes RSV replication and its induction, assessed by Northern blot and a new qRT-PCR-based method, is regulated by ribonuclease ELAC2. ELAC2-mediated tRF5 induction has never been reported. We also found that ELAC2 is associated with RSV N and NS1 proteins. Given the fact that tRF5-GlnCTG plays a role in RSV replication, the identification of ELAC2 being responsible for tRF5-GlnCTG induction could provide new insights into therapeutic strategy development against RSV infection.

Epidemiology of Respiratory Syncytial Virus-related Hospitalizations and the Influence of Viral Coinfections in Southern Austria in a 7-year Period

OBJECTIVE

The aim of this study was to determine the respiratory syncytial virus (RSV) epidemiology and to analyze the influence of risk factors and coinfections over the last years.

METHODS

Retrospectively all infants, children and adolescents hospitalized due to respiratory disease with positive RSV test [hospitalized for RSV infection (RSV-H)] between January 1, 2009, and December 31, 2015, at a tertiary care center in the southern part of Austria were included for analysis. Patients were all identified by a search via International Classification of Diseases and Related Health Problems, 10th Edition codes, and all medical data were collected from the local electronic databases called openMedocs. RSV tests had to prove true infection case definition.

RESULTS

During a 7-year study period, 745 infants, children and adolescents exhibited RSV-H. Main diagnosis was bronchiolitis (70%). Nearly half of all cases (44%) were born during the first half of the RSV season (November-January), and seasonal peak of RSV-H was in January. Predominant underlying condition was history of prematurity in 15% followed by neurologic impairment (3.5%) and hemodynamically significant congenital heart disease (2.95%). Age ≤2 months and underlying conditions/morbidities were associated with more severe disease. The majority of cases (96%) had an age below 24 months, and 91% below 12 months. Viral coinfection (most common influenza virus, adenovirus and rhinovirus) was diagnosed in 37 cases (5%) resulting in a more severe course of disease. Main risk factors of coinfection were siblings and crowding. Mortality was 0.27% (2/745). Both children had coinfection with influenza A virus and were multihandicapped (15 and 20 years of age, respectively).

CONCLUSIONS

Prematurity and underlying morbidities play a marked role in RSV-H. Viral coinfections aggravated disease with death in 2 multihandicapped adolescents.

Cost-effectiveness of rule-based immunoprophylaxis against respiratory syncytial virus infections in preterm infants

The objective of the paper is to assess the cost-effectiveness of targeted respiratory syncytial virus (RSV) prophylaxis based on a validated prediction rule with 1-year time horizon in moderately preterm infants compared to no prophylaxis. Data on health care consumption were derived from a randomised clinical trial on wheeze reduction following RSV prophylaxis and a large birth cohort study on risk prediction of RSV hospitalisation. We calculated the incremental cost-effectiveness ratio (ICER) of targeted RSV prophylaxis vs. no prophylaxis per quality-adjusted life year (QALYs) using a societal perspective, including medical and parental costs and effects. Costs and health outcomes were modelled in a decision tree analysis with sensitivity analyses. Targeted RSV prophylaxis in infants with a first-year RSV hospitalisation risk of > 10% resulted in a QALY gain of 0.02 (0.931 vs. 0.929) per patient against additional cost of €472 compared to no prophylaxis (ICER €214,748/QALY). The ICER falls below a threshold of €80,000 per QALY when RSV prophylaxis cost would be lowered from €928 (baseline) to €406 per unit. At a unit cost of €97, RSV prophylaxis would be cost saving.

CONCLUSIONS

Targeted RSV prophylaxis is not cost-effective in reducing RSV burden of disease in moderately preterm infants, but it can become cost-effective if lower priced biosimilar palivizumab or a vaccine would be available.

Respiratory syncytial virus hospitalization risk in the second year of life by specific congenital heart disease diagnoses

Children with hemodynamically significant congenital heart disease (CHD) are at elevated risk of morbidity and mortality due to respiratory syncytial virus (RSV) disease compared to their healthy peers. Previous studies have demonstrated lower RSV hospitalization risk among all children with CHD at 12-23 months of age versus 0-11 months of age. However, RSV hospitalization risk at 12-23 months of age by specific CHD diagnosis has not been characterized. Both case-control and cohort studies were conducted using data from the US National Inpatient Sample from 1997 to 2013 to characterize relative risk of RSV hospitalization among children 12-23 months of age with CHD. Related CHD diagnoses were combined for analysis. Hospitalizations for RSV and unspecified bronchiolitis were described by length of stay, mechanical ventilation use, mortality, and total charges. Over the 17-year period, 1,168,886 live birth hospitalizations with CHD were identified. Multiple specific CHD conditions had an elevated odds ratio or relative risk of RSV hospitalization. Mean total RSV hospitalization charges were significantly higher among children with CHD relative to those without CHD ($19,650 vs $7,939 in 2015 dollars) for this period. Compared to children without CHD, children with Ebstein's anomaly, transposition of the great arteries, aortic stenosis, heterotaxia, and aortic arch anomalies had 367-, 344-, 203-, 117- and 47-fold increased risk of inpatient RSV mortality, respectively. Unspecified bronchiolitis hospitalization odds and relative risk across CHD diagnoses were similar to those observed with RSV hospitalization; however, unspecified bronchiolitis hospitalizations were associated with shorter mean days of stay and less frequently associated with mechanical ventilation or mortality. Among children with more severe CHD diagnoses, RSV disease remains an important health risk through the second year of life. These data can help inform decisions regarding interventions to protect children with CHD from severe RSV disease during their second year of life.

Respiratory syncytial virus hospitalizations in infants of 28 weeks gestational age and less in the palivizumab era

OBJECTIVE

To obtain data on respiratory syncytial virus (RSV) associated hospitalization rates in preterm infants of 28 weeks gestational age and less in the era of palivizumab prophylaxis.

METHODS

Retrospective single-center cohort study including all preterm infants up to 28 weeks+6days gestational age and born between 2004 and 2012 at a tertiary care university hospital. Data on RSV related hospitalizations over the first two years of life covering at least two RSV seasons (November-April) were analyzed.

RESULTS

Ninety-one of 287 (32%) infants were hospitalized due to respiratory illness, and a total of 17 infants (5.9%) tested RSV positive during the first 2 years of life. Fourteen infants (4.9%) were hospitalized during the first RSV season. RSV hospitalization rate in infants with BPD was 4.5% (2/44) compared to 4.9% (12/243) without BPD. Palivizumab prophylaxis was documented in 74.6% of the infants. Infants with RSV compared to other respiratory tract infection were of younger age (6.8 vs. 9.1 months; p=0.049), had longer hospital stays (median 11 vs. 5 days; p=0.043) and more severe respiratory illness (median LRI score 3 vs. 2; p=0.043).

CONCLUSIONS

Despite palivizumab prophylaxis the burden of RSV disease and all cause respiratory illness was still remarkable in this vulnerable preterm population and mainly limited to the first season.

Defining the Risk and Associated Morbidity and Mortality of Severe Respiratory Syncytial Virus Infection Among Infants with Chronic Lung Disease

INTRODUCTION

The REGAL (RSV evidence-a geographical archive of the literature) series provide a comprehensive review of the published evidence in the field of respiratory syncytial virus (RSV) in Western countries over the last 20 years. This third publication covers the risk and burden of RSV infection in infants with chronic lung disease (CLD), formerly called bronchopulmonary dysplasia (BPD).

METHODS

A systematic review was undertaken of publications between January 1, 1995 and December 31, 2015 across PubMed, Embase, The Cochrane Library, and Clinicaltrials.gov. Studies reporting data for hospital visits/admissions for RSV infection among infants with CLD/BPD who were not prophylaxed, as well as studies reporting RSV-associated morbidity, mortality, and healthcare costs, were included. Burdens of disease data were compared with preterm infants without CLD/BPD, other high-risk groups and term infants. Study quality and strength of evidence (SOE) were graded using recognized criteria.

RESULTS

A total of 1837 studies were identified and 39 were included. CLD/BPD is a significant independent risk factor for RSV hospitalization [RSVH (odds ratio 2.2-7.2); high SOE]. Infants and young children with CLD/BPD had high RSVH rates which were generally similar in Europe, the United States, and Canada, mostly varying between 12 and 21%. Infants with CLD also had a longer length of hospital stay than other high-risk groups and term infants (high SOE). On average, infants spent 4-11 days in hospital (moderate SOE). Once hospitalized for RSV, affected children were at risk for a more severe course of disease than children with no RSVH (moderate SOE).

CONCLUSION

Severe RSV infection in infants and young children with CLD/BPD poses a significant health burden in Western countries. Further studies focussing on the burden of RSV infection in this well-recognized population at high risk for severe disease are needed to help improve outcomes and plan allocation of healthcare resources.

FUNDING

AbbVie.

Risk Factors of Early Otitis Media in the Danish National Birth Cohort

OBJECTIVE

To assess risk factors of otitis media (OM) in six-months-old children.

METHOD

The sample consisted of 69,105 mothers and their children from the Danish National Birth Cohort. The women were interviewed twice during pregnancy and again 6 months after birth. The outcome "one or more" maternal reported episodes of OM at age six months. In total 37 factors were assessed, covering prenatal, maternal, perinatal and postnatal factors.

RESULTS

At age six months 5.3% (95% CI 5.1-5.5) of the children had experienced one or more episodes of OM. From the regression analysis, 11 variables were associated with a risk of OM. When a Bonferroni correction was introduced, gender, prematurity, parity, maternal age, maternal self-estimated health, taking penicillin during pregnancy, and terminating breastfeeding before age six months, was associated with a risk of early OM. The adjusted ORs of OM for boys versus girls was 1.30 (95% CI 1.18-1.44). The OR having one sibling versus no siblings was 3.0 (95% CI 2.64-3.41). If the woman had been taking penicillin during pregnancy, the OR was 1.35 (95% CI 1.15-1.58). Children born before 38th gestational week had an increased OR for early OM of 1.49 (95% CI 1.21-1.82). Children of young women had an increased OR of early OM compared to children of older women. Additionally, children of women who rated their own health low compared to those rating their health as high, had an increased OR of 1.38 (95% CI 1.10-1.74). Finally, children being breastfeed less than 6 months, had an increased OR of 1.42 (95% CI 1.28-1.58) compared to children being breastfeed beyond 6 months.

CONCLUSION

These findings indicate that prenatal factors are of less importance regarding early OM before the age of six months. Postnatal risk factors seem to pose the main risk of early OM.

Differences Between Radiologically Confirmed Pneumonia With and Without Pleural Fluid in Hospitalized Children Younger Than 5 Years in Southern Israel

We compared demographic and clinical characteristics of pneumonia with and without pleural fluid (PF and Pn, respectively) in hospitalized children younger than 5 years in southern Israel, between 2002 and 2011. Overall, 108 PF and 5811 Pn episodes were recorded. Children with PF were older. Prematurity (6.6% vs 14.0%) and asthma (9.9% vs 23.5%) were less common in PF. Mean temperature and saturation were higher in PF while hemoglobin and sodium levels were lower in PF compared with Pn. Nasal washes were obtained in 30.6% and 39.9% of PF and Pn episodes, respectively, with respiratory syncytial virus identified more commonly in Pn (24.2% vs 42.3%). Streptococcus pneumoniae was identified in 5.2% and 0.9% of blood cultures in PF and Pn, respectively. In conclusion, PF differed from Pn in demographic and clinical characteristics, possibly due to differences in etiology. Although both diseases are considered bacterial, a high proportion of viral etiology was found in both, especially in Pn.

Risk of respiratory syncytial virus infection in preterm infants: reviewing the need for prevention

Premature infants are at substantial risk for a spectrum of morbidities that are gestational age dependent. Respiratory syncytial virus (RSV) infection is most common in the first two years of life with the highest burden in children aged <6 months. Preterm infants ≤35 weeks' gestation are handicapped by incomplete immunological and pulmonary maturation and immature premorbid lung function with the added risk of bronchopulmonary dysplasia. Superimposed RSV infection incites marked neutrophilic airway inflammation and innate immunological responses that further compromise normal airway modeling. This review addresses the epidemiology and burden of RSV disease, focusing on the preterm population. Risk factors that determine RSV-disease severity and hospitalization and the impact on healthcare resource utilization and potential long-term respiratory sequelae are discussed. The importance of disease prevention and the evidence-based rationale for prophylaxis with palivizumab is explored, while awaiting the development of a universal vaccine.

Clinical and Virological Characteristics of Early and Moderate Preterm Infants Readmitted With Viral Respiratory Infections

BACKGROUND

Rehospitalization of children born prematurely (referred to as preterm children) caused by severe respiratory infections is common. Most studies have focused on respiratory syncytial virus infection. We designed a study to determine the virological and clinical characteristics of severe respiratory infections of children born early (<32 weeks) and moderate preterm (32 to 36 weeks), and compared them with full term (FT; ≥37 weeks) children who were subsequently admitted with respiratory illness.

METHODS

A 7-year observational prospective study was conducted on preterm and FT children, less than 14 years old hospitalized with respiratory infection. The presence of 16 respiratory viruses in nasopharyngeal aspirates was sought. Clinical and virological characteristics of subjects were compared among term and preterm children.

RESULTS

We studied 411 respiratory hospital admissions of 262 preterm children who were compared with 2057 respiratory hospital admissions of term children. In 78.6% of preterm episodes, at least 1 respiratory virus was identified. The most frequent viruses were respiratory syncytial virus (29%), rhinovirus (25%) and human bocavirus (13%). Human metapneumovirus and parainfluenza virus were significantly more frequent in preterm than in term children (P < 0.001 and P = 0.017, respectively). Early preterm (EPT) infants admitted with bronchiolitis presented more hypoxia (P = 0.08), longer hospital stay (P = 0.05), more infiltrate on chest radiograph (P = 0.02) and more antibiotic treatment (P = 0.02) than moderate preterm (MPT) infants. Moreover, MPT needed more intensive care unit admission than FT infants (P < 0.001). Regarding wheezing episodes, EPT patients showed significantly more infiltrate/atelectasis (P < 0.001), longer oxygen therapy (P = 0.039) and longer hospital stay (P = 0.07) than MPT children, although similar percentage of intensive care unit admission was seen in both groups. MPT-wheezy children needed longer hospital stay than FT (P = 0.05). Previous bronchiolitis and EPT were independent factors associated with multiple wheezing admissions.

CONCLUSION

Our results demonstrate that besides respiratory syncytial virus, other viruses mainly rhinovirus and human bocavirus are important pathogens in severe respiratory infections in preterm children. Human metapneumovirus and parainfluenza virus seem also to play a significant role in this group of children. There is increased medical resource utilization, not only among EPT but also in MPT hospitalized children with respiratory infections as many of them require more medical support than FT children.

Genotype circulation pattern of human respiratory syncytial virus in Iran

In order to have information on the molecular epidemiology and genetic circulation pattern of human respiratory syncytial virus (HRSV) in Iran, we studied the genetic variability of both group A and B HRSV strains during seven consecutive years by sequencing the hypervariable C-terminal domain of G protein. A total of 485 children <2years of age who were negative for influenza viruses, screened for the presence of HRSV in this research. HRSV was detected in 94 (19.38%) of the samples using nested RT-PCR. Group A viruses were isolated during each year, while group B viruses were isolated during 2009 and 2013. Phylogenetic analysis showed that all HRSV group A viruses belonged to three genotypes: GA1, GA2, GA5 and the group B viruses were in BA genotype.

The clinical utility of a near patient care rapid microarray-based diagnostic test for influenza and respiratory syncytial virus infections in the pediatric setting

We evaluated the potential clinical utility of an automated near patient molecular assay Verigene Respiratory Virus Plus (RV+) and rapid immunochromatographic antigen tests (RIAT) in the pediatric setting for diagnosis of influenza and respiratory syncytial virus infections when testing was performed by the pediatrician seeing the patient. Overall, with respect to influenza virus, sensitivity and specificity for RIAT were 70.8% and 100%, respectively, compared to 100% and 96.2%, respectively, for RV+. For respiratory syncytial virus, sensitivity and specificity for RIAT were 78.9% and 100%, respectively, compared to 100% and 100%, respectively, for RV+. When RIAT and RV+ sensitivity for influenza virus was compared based on the time the patient presented after onset of fever, the sensitivity of RIAT at 6 hours was 37.5% compared to 100% for RV+. At 12 hours, RIAT improved to 60.9%. This study confirms the clinical utility of RV+ in the pediatric setting.

Apnea in children hospitalized with bronchiolitis

OBJECTIVE

To identify risk factors for inpatient apnea among children hospitalized with bronchiolitis.

METHODS

We enrolled 2207 children, aged <2 years, hospitalized with bronchiolitis at 16 sites during the winters of 2007 to 2010. Nasopharyngeal aspirates (NPAs) were obtained on all subjects, and real-time polymerase chain reaction was used to test NPA samples for 16 viruses. Inpatient apnea was ascertained by daily chart review, with outcome data in 2156 children (98%). Age was corrected for birth <37 weeks. Multivariable logistic regression was performed to identify independent risk factors for inpatient apnea.

RESULTS

Inpatient apnea was identified in 108 children (5%, 95% confidence interval [CI] 4%-6%). Statistically significant, independent predictors of inpatient apnea included: corrected ages of <2 weeks (odds ratio [OR] 9.67) and 2 to 8 weeks (OR 4.72), compared with age ≥ 6 months; birth weight <2.3 kg (5 pounds; OR 2.15), compared with ≥ 3.2 kg (7 pounds); caretaker report of previous apnea during this bronchiolitis episode (OR 3.63); preadmission respiratory rates of <30 (OR 4.05), 30 to 39 (OR 2.35) and >70 (OR 2.26), compared with 40 to 49; and having a preadmission room air oxygen saturation <90% (OR 1.60). Apnea risk was similar across the major viral pathogens.

CONCLUSIONS

In this prospective, multicenter study of children hospitalized with bronchiolitis, inpatient apnea was associated with younger corrected age, lower birth weight, history of apnea, and preadmission clinical factors including low or high respiratory rates and low room air oxygen saturation. Several bronchiolitis pathogens were associated with apnea, with similar apnea risk across the major viral pathogens.

Association between respiratory syncytial virus hospitalizations in infants and respiratory sequelae: systematic review and meta-analysis

BACKGROUND

The association between hospitalization for respiratory syncytial virus (RSV) infection in infancy and asthma/wheezing in later life has long been studied. However, no published studies have combined systematic review and meta-analysis of existing evidence.

PURPOSE

To quantify the link between RSV hospitalization in early life and subsequent diagnosis of asthma.

METHOD

A systematic search was conducted using MEDLINE and EMBASE databases. Studies were selected for meta-analysis if they assessed the association between RSV-confirmed hospitalization for up to 3 years of age and asthma/wheezing later in life. Potential sources of heterogeneity were identified by stratified analysis.

RESULTS

Twenty articles representing 15 unique studies of 82,008 unique individuals (including 1533 with RSV-confirmed hospitalization) were selected for meta-analysis. Children who had RSV disease in early life had a higher incidence of asthma/wheezing in later life (odds ratio: 3.84; 95% confidence interval: 3.23-4.58). There was moderate heterogeneity between studies (I² = 45%). The association was found to decrease with age at follow-up, consistent with the findings of longitudinal studies. When age at follow-up was considered, heterogeneity was low (residual I² = 17%).

LIMITATIONS

Study quality was generally poor because randomization to hospitalization for RSV infection was not possible, appropriate blinding was rare and adjustment for confounding variables was not always appropriate.

CONCLUSIONS

The meta-analysis suggests an association between infant RSV hospitalization and respiratory morbidity that decreases with age. If the association is causal, the development of an effective vaccine against RSV could decrease the burden of asthma.

Respiratory syncytial virus infections in infants and children with congenital heart disease: update on the evidence of prevention with palivizumab

PURPOSE OF REVIEW

Lower respiratory tract infections multiply morbidity and mortality within patients with significant congenital heart disease (CHD). For respiratory syncytial virus (RSV), one of the most important pathogens, immunoprophylaxis with palivizumab has successfully been introduced. The question is which patients will benefit most from this costly preventive treatment.

RECENT FINDINGS

The era after the introduction of palivizumab has revealed a steep decrease in mortality. The markers of success - hospital stays, admission to the intensive care unit, days on mechanical ventilation, and death - consistently favor immunoprophylaxis. The key point of treatment success remains in all cases a careful patient selection, adherence to a time limit of 30 days between the injections and early use after cardiac surgery with cardiopulmonary bypass, as well as avoidance of nosocomial-acquired infections. Preventive therapy with palivizumab in patients with CHD has been investigated in terms of operating efficiency - with the lowest costs per quality-adjusted life years compared with preterm infants with or without bronchopulmonary dysplasia.

SUMMARY

The burden of RSV disease will decline, once a vaccine is available. Meanwhile, immunoprophylaxis with palivizumab is a useful tool for high-risk patients to reduce comorbidity and fatal outcome. Pharmacoeconomic considerations measuring quality-adjusted life years indicate important information about cost-effectiveness.

Should respiratory care in preterm infants include prophylaxis against respiratory syncytial virus infection? The case in favour

Respiratory syncytial virus (RSV) is the most significant cause of acute respiratory tract infections (RTI) in infants and young children throughout the world. Preterm infants are at increased risk for severe RSV lower respiratory tract infection due to small lung volumes, a reduced lung surface area, small airways and an increased air space wall thickness. Additionally, the airways of preterm infants have been ventilated mechanically and suctioned and potentially damaged by many microtraumas with disruption of endothelial surfaces enabling pathogens to invade more easily. The immune system of preterm infants is immature resulting in low antibody titers (incomplete transplacental transfer of maternal antibodies) and a reduced cellular immunity with reduced viral clearance. Rehospitalization rates of preterm compared to term infants due to RSV infection are increased as are total morbidity and mortality associated with RSV disease. Palivizumab effectively reduces RSV related rehospitalisation in this high-risk population.

Respiratory viruses in neonates hospitalized with acute lower respiratory tract infections

BACKGROUND

The burden of respiratory syncytial virus (RSV) in neonates has not been clearly studied. The aims of this study were to determine the overall distribution of respiratory viruses in neonates hospitalized with acute lower respiratory tract infectiosns (ALRI) and to describe the clinical characteristics of RSV infections in these neonates.

METHODS

From January 2009 through May 2010, neonates aged <1 month who were hospitalized with ALRI and did not have underlying disease were included in the study. Viruses were identified on multiplex reverse transcription polymerase chain reaction using nasal swab samples. Clinical variables were evaluated between the RSV and non-RSV infection groups.

RESULTS

Of the 108 infants included in the study, 46 (42.6%) had RSV; human rhinovirus (18.5%), human parainfluenza virus 3 (7.5%), and human metapneumovirus (3.7%) were the next most common infections. Codetections accounted for 8.3% of the cases. Crowding increased the risk of RSV infection compared to the non-RSV group (OR, 16.5; P = 0.001). The RSV group had a greater incidence of dyspnea (P = 0.027), pneumonia (P < 0.001), requirement for oxygen (P < 0.001), and prolonged hospitalization (P = 0.011) than the non-RSV group.

CONCLUSIONS

RSV was the most common viral etiology in neonates without underlying diseases who were hospitalized with ALRI. The disease severity of RSV infection was worse than that of other detected viral infections. Strict prevention strategies should be considered in overcrowded situations.

Ethical considerations and rationale of the MAKI trial: a multicenter double-blind randomized placebo-controlled trial into the preventive effect of palivizumab on recurrent wheezing associated with respiratory syncytial virus infection in children with a gestational age of 33-35 weeks

BACKGROUND

Respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) is the most frequent cause of bronchiolitis during infancy. Long-term airway morbidity with recurrent post bronchiolitis wheezing (PBW) episodes, which are probably associated with respiratory infections, occurs in 30 to 70% of infants that were hospitalised with RSV LRTI.

METHODS

We set up a multicenter, placebo-controlled double-blind randomized clinical trial in healthy preterm infants born between 33 and 35 weeks gestational age (WGA). The children received either one-monthly intramuscular palivizumab or placebo injection during the RSV season with a minimum of 2 injections.

RESULTS

The primary objective was to determine the preventive effect of RSV immunoprophylaxis (palivizumab) on the development of recurrent wheezing during the first year of life. The primary outcome measure was the number of wheezing days during the first year of life as obtained by daily logs. As a secondary outcome nasal swabs were taken for viral analysis in case of respiratory symptoms. We will also examine wheezing at age 1, 3 and 6 years both reported by the parents and the general practitioner and quality of life as secondary outcomes. This trial is possible because RSV immunoprophylaxis, although effective in this population, is not completely used in the Netherlands due to its high costs.

CONCLUSION

The Institutional review board (IRB) concluded the study has high clinical relevance because the benefit of 50% chance of protection by palivizumab outweighs the risk of side adverse events due to intramuscular administration of placebo.

Maternal smoking during pregnancy, prematurity and recurrent wheezing in early childhood

BACKGROUND

Prenatal maternal smoking and prematurity independently affect wheezing and asthma in childhood.

OBJECTIVE

We sought to evaluate the interactive effects of maternal smoking and prematurity upon the development of early childhood wheezing.

METHODS

We evaluated 1,448 children with smoke exposure data from a prospective urban birth cohort in Boston. Maternal antenatal and postnatal exposure was determined from standardized questionnaires. Gestational age was assessed by the first day of the last menstrual period and early prenatal ultrasound (preterm < 37 weeks gestation). Wheezing episodes were determined from medical record extraction of well and ill/unscheduled visits. The primary outcome was recurrent wheezing, defined as ≥ 4 episodes of physician documented wheezing. Logistic regression models and zero inflated negative binomial regression (for number of episodes of wheeze) assessed the independent and joint association of prematurity and maternal antenatal smoking on recurrent wheeze, controlling for relevant covariates.

RESULTS

In the cohort, 90 (6%) children had recurrent wheezing, 147 (10%) were exposed to in utero maternal smoke and 419 (29%) were premature. Prematurity (odds ratio [OR] 2.0; 95% confidence interval [CI], 1.3-3.1) was associated with an increased risk of recurrent wheezing, but in utero maternal smoking was not (OR 1.1, 95% CI 0.5-2.4). Jointly, maternal smoke exposure and prematurity caused an increased risk of recurrent wheezing (OR 3.8, 95% CI 1.8-8.0). There was an interaction between prematurity and maternal smoking upon episodes of wheezing (P = 0.049).

CONCLUSIONS

We demonstrated an interaction between maternal smoking during pregnancy and prematurity on childhood wheezing in this urban, multiethnic birth cohort.

Risk factors for severe respiratory syncytial virus lower respiratory tract infection

RSV infection is a leading cause of lower respiratory tract infection, especially in High-risk infants with a history of prematurity, bronchopulmonary dysplasia (BPD), congenital heart disease (CHD), neuromusculair impairment, immunodeficiency, and Down syndrome. Host related risk factors that have been identified to be associated with severe RSV related lower respiratory tract infection include young age below 6 months at the beginning of RSV season, multiple birth, male sex, low socioeconomic status and parental education, crowded living conditions, young siblings, maternal smoking and indoor smoke pollution, malnutrition/small for gestational age, family history of atopy or asthma, low cord serum RSV antibody titers, and living at altitude.Risk factors increasing the risk of acquisition of RSV have been identified to be birth before and/or during RSV season, day care attendance, presence of older siblings in school or day-care, and lack of breast feeding. Some of these risk factors are discussed controversially and some of them are found continuously throughout the literature.Given the high cost of RSV prophylaxis, especially for the large population of late preterm infants, algorithms and risk score systems have been published that could identify high-risk infants for treatment with palivizumab out of this gestational age group. Several models reported on an average sensitivity and specificity of 70 percent and, thus, are helpful to identify infants at high risk for severe RSV infection and need for prophylaxis with palivizumab.

Respiratory syncytial virus infection in children with neuromuscular impairment

Clinically obvious reasons why children with neurological impairment (NMI) may be more severely affected in case of a viral respiratory tract infection include reduced vital capacity due to muscular weakness or spastic scoliosis, disturbed clearance of respiratory excretions (weak coughing and dysphagia), inability to comply actively with physiotherapeutic interventions, recurrent micro-aspirations (gastroesophageal reflux disease, vomiting related to coughing), a history of frequent exposure to antibiotics and health care institutions, colonization with resistant pathogens, impaired immunologic defence mechanisms due to severe malnutrition and cachexia, and early clinical deterioration in case of high fever with metabolic acidosis and hypercapnia, and maybe associated seizures or febrile convulsions.

Data from the literature suggests that in all children with NMI, who have to be hospitalized with severe clinical deterioration due to an airway infection, at least one specimen of nasopharyngeal secretions should be sent as soon as possible to a virologic laboratory to detect viral pathogens. Children with severe NMI and those mechanically ventilated for other reasons being hospitalized during the RSV season must be strictly protected against nosocomial RSV infection by means of standard and droplet precautions. Finally, children with severe NMI and age below 24 months of life should receive passive immunization with palivizumab following international recommendations.

CARESS: the Canadian registry of palivizumab

BACKGROUND

Palivizumab is indicated for respiratory syncytial virus (RSV) prophylaxis in high-risk children. However, relatively little is known about the current use, compliance, and outcomes associated with this medication.

METHODS

A prospective, observational, registry based on 27 sites, with monthly follow-up of infants at high risk for RSV who received at least 1 dose of palivizumab during the 2005-2009 RSV seasons.

RESULTS

A total of 5286 children were enrolled (56.6% male; 71.7% white; average gestational age, 32.1 ± 5.5 weeks). Of them, 3741 patients (70.8%) were prophylaxed for prematurity only, 449 (8.5%) for bronchopulmonary dysplasia/chronic lung disease, 508 (9.6%) for congenital heart disease, and 588 (11.1%) for other reasons. Overall, 19,485 doses were given. On average, infants received 86.0% ± 28.4% of their expected number of injections; 71.2% of infants received their injections in the recommended time periods. Of the 5286 participants enrolled, 308 patients were hospitalized for respiratory tract illness (hospitalization rate, 5.8%). The RSV-hospitalization rate was calculated as 1.38%. Having siblings increased likelihood of hospitalization (66.9% vs. 55.7%, P < 0.005), and was significantly correlated with time to hospitalization in this cohort (P = 0.050).

CONCLUSIONS

The overall RSV-hospitalization rate in our study was within the range found in previous reports (1.3%-5.3%), although it did not mimic the declining rates of the US Palivizumab Outcomes Registry. This could be due to increased testing for RSV when hospitalized and increasing rates of prophylaxis of infants with underlying medical disorders.

Fatality rates in published reports of RSV hospitalizations among high-risk and otherwise healthy children

OBJECTIVE

To review the fatalities among children hospitalized with respiratory syncytial virus (RSV) infection, and identify factors leading to a fatal outcome.

RESEARCH DESIGN AND METHODS

Review of literature identified from a structured search of PubMed (1966-2009) using the following Medical Subject Headings: respiratory syncytial virus infection; hospitalized; infants; and risk factors. Publications were restricted to: English language; full papers; inclusion of > or =10 subjects; children aged < or =18 years, hospitalization for RSV infection; and deaths reported. Case fatality rates were defined as number of deaths divided by number of children hospitalized for RSV and were calculated for each study.

RESULTS

Thirty-six studies met the inclusion and exclusion criteria. Case fatality rates among children hospitalized for RSV ranged from 0 to 33%. In general, studies showed that subgroups of high-risk children (chronic lung disease [CLD] 3.5-23%, congenital heart disease [CHD] 2-37%, and prematurity 0-6.1%) had higher fatality rates than older or otherwise healthy children (consistently <1%). Presence of severe underlying comorbidities such as neuromuscular disease, immunosuppression, and malignancies was associated with death among term and/or older (>1 year) children. Higher fatality rates were reported for infants receiving intensive unit care (1.1-8.6%), extracorporeal life support (33%) or for those who acquired nosocomial RSV infection (0-12.2%). The majority of studies did not report cause of death and clinical details of the fatal cases were often not provided. Other limitations of this review include our search limits, the possibility of inherent bias in our methodology that could result in an under or over estimation of case-fatality rates, and potential publication bias.

CONCLUSIONS

Children at high risk for RSV (CLD, CHD and prematurity), those with severe underlying comorbidities, or those with nosocomial RSV appear to be at increased risk for death after RSV hospitalization. More data are needed on cause of death and how much is directly attributable to RSV.

[Consensus conference on acute bronchiolitis (VI): prognosis of acute bronchiolitis. Review of scientific evidence]

We present a review of the evidence on prognosis of acute bronchiolitis, risk factors for severe forms, symptom or severity scores and risk of post-bronchiolitis asthma. Documented risk factors of long stay or PICU admission in hospitalized patients are: bronchopulmonary dysplasia and/or chronic lung disease, prematurity, congenital heart disease and age less than 3 months. Other less well documented risk factors are: tobacco exposure, history of neonatal mechanical ventilation, breastfeeding for less than 4 months, viral co-infection and other chronic diseases. There are several markers of severity: toxic appearance, tachypnea, hypoxia, atelectasis or infiltrate on chest radiograph, increased breathing effort, signs of dehydration, tachycardia and fever. Although we have some predictive models of severity, none has shown sufficient predictive validity to recommend its use in clinical practice. While there are different symptom or severity scores, none has proven to be valid or accurate enough to recommend their preferable application in clinical practice. There seems to be a consistent and strong association between admission due to bronchiolitis and recurrent episodes of wheezing in the first five years of life. However it is unclear whether this association continues in subsequent years, as there are discordant data on the association between bronchiolitis and asthma.

Neurological complications of respiratory syncytial virus infection: case series and review of literature

Respiratory syncytial virus is a common cause of infection in children. The authors summarize the clinical and diagnostic features of 9 patients admitted to the pediatric intensive care unit with neurological consultation. Patients were aged 5 weeks to 3 years. Four had seizures, 4 had cardiac arrest, and 1 had hypertonia. Results of brain magnetic resonance imaging in 5 patients was abnormal in 1. Cerebrospinal fluid in 4 patients showed elevated protein in 1. Serum sodium was low in 2 patients and normal in 7. Electroencephalograms in 8 patients were abnormal in 7. Increased risk of neurological complications of respiratory syncytial virus should be considered in any patient with documented infection requiring intensive care. Clinical manifestations may include seizures, encephalopathy, and abnormal neurological examination. The authors' data suggest that the electroencephalogram provides a sensitive method for detection of neurological insult in this group of patients.

Protective efficacy and immunogenicity of an adenoviral vector vaccine encoding the codon-optimized F protein of respiratory syncytial virus

Adenoviral vectors (AdV) have received considerable attention for vaccine development because of their high immunogenicity and efficacy. In previous studies, it was shown that DNA immunization of mice with codon-optimized expression plasmids encoding the fusion protein of respiratory syncytial virus (RSV F) resulted in enhanced protection against RSV challenge compared to immunization with plasmids carrying the wild-type cDNA sequence of RSV F. In this study, we constructed AdV carrying the codon-optimized full-length RSV F gene (AdV-F) or the soluble form of the RSV F gene (AdV-Fsol). BALB/c mice were immunized twice with AdV-F or AdV-Fsol and challenged with RSV intranasally. Substantial levels of antibody to RSV F were induced by both AdV vaccines, with peak neutralizing-antibody titers of 1:900. Consistently, the viral loads in lung homogenates and bronchoalveolar lavage fluids were significantly reduced by a factor of more than 60,000. The protection against viral challenge could be measured even 8 months after the booster immunization. AdV-F and AdV-Fsol induced similar levels of immunogenicity and protective efficacy. Therefore, these results encourage further development of AdV vaccines against RSV infection in humans.

Incidence of apnea in infants hospitalized with respiratory syncytial virus bronchiolitis: a systematic review

OBJECTIVE

To determine the incidence of apnea in infants hospitalized with respiratory syncytial virus (RSV) bronchiolitis and identify relevant risk factors from the available literature.

STUDY DESIGN

A systematic search of available databases for studies reporting the rate of apnea in a consecutive cohort of infants hospitalized with RSV infection was performed. The overall incidence of apnea was extracted and analyzed in relation to preterm birth, age, and potentially confounding illnesses.

RESULTS

The incidence of apnea in the study population of 5575 hospitalized patients with RSV ranged from a high of 23.8% to a low of 1.2%. Comparison of the cohort by term and preterm birth revealed an expected excess in apnea incidence in preterms, even in the absence of information about chronologic age. Many studies appeared to be confounded by the inclusion of impaired infants with neuromuscular disorders.

CONCLUSIONS

Based on the available data, precisely quantifying the risk of apnea attributable to RSV infection is not possible. Factors intrinsic to the individual infants may account for a significant percentage of the apnea attributed to RSV. Recent studies have found a < 1% incidence of apnea with RSV in previously healthy term infants.

The year in review

Over the last year there have been more studies determining predisposition to severe bronchiolitis and its consequences. Studies have highlighted various single-nucleotide polymorphisms (SNPs) to be significantly associated with respiratory syncytial virus (RSV) hospitalisation, and a candidate gene approach demonstrated that innate immune gene SNPs had the strongest association with bronchiolitis. The impact of 'other' viruses (RSV, influenza, adenovirus, parainfluenza, rhinovirus, human metapneumovirus [hMPV], coronavirus, boca-virus, enterovirus, paraechovirus) has been investigated. In one series only children with RSV infection experienced recurrent wheezing and in another only RSV infection was associated with respiratory complications (hypoxia correlated with prolonged hospitalisation). Others have examined the long-term outcome of viral infection in infancy. The above studies and others published in the last year will be discussed.

Respiratory syncytial virus infection in children admitted to hospital but ventilated mechanically for other reasons

One thousand five hundred sixty-eight RSV infections were documented prospectively in 1,541 pediatric patients. Of these, 20 (1.3%) had acquired the RSV infection while treated by mechanical ventilation for reasons other than the actual RSV infection (group ventilated mechanically). The clinical characteristics of children who were infected with respiratory syncytial virus (RSV) infection while ventilated mechanically for other reasons are described and compared with a matched control group. Sixty percent of the group ventilated mechanically had at least one additional risk factor for a severe course of infection (prematurity 50%, chronic lung disease 20%, congenital heart disease 35%, immunodeficiency 20%). The median age at diagnosis in the group ventilated mechanically was 4.2 months. The matched pairs analysis (group ventilated mechanically vs. control group) revealed a higher proportion of patients with hypoxemia and apnoea in the group ventilated mechanically; more patients in the control group showed symptoms of airway obstruction (wheezing). At least one chest radiography was performed in 95% of the patients (n = 19) in the group ventilated mechanically versus 45% (n = 9) in the control group (P = 0.001). The frequency of pneumonia was 40% in the group ventilated mechanically and 20% in the control group. Despite existing consensus recommendations, only two patients (10%) of the group ventilated mechanically had received palivizumab previously. Significantly more patients in the group ventilated mechanically received antibiotic treatment (85% vs. 45%, P = 0.008), and attributable mortality was higher in the group ventilated mechanically (15% [n = 3] vs. 0% in the control group, P = 0.231). Children treated by long term mechanical ventilation may acquire RSV infection by transmission by droplets or caregivers and face an increased risk of a severe course of RSV infection. The low rate of immunoprophylaxis in this particular risk group should be improved.

Prospective population-based study of RSV-related intermediate care and intensive care unit admissions in Switzerland over a 4-year period (2001-2005)

OBJECTIVES

Respiratory syncytial virus (RSV) infections are a leading cause of hospital admissions in small children. A substantial proportion of these patients require medical and nursing care, which can only be provided in intermediate (IMC) or intensive care units (ICU). This article reports on all children aged < 3 years who required admission to IMC and/or ICU between October 1, 2001 and September 30, 2005 in Switzerland.

PATIENTS AND METHODS

We prospectively collected data on all children aged < 3 years who were admitted to an IMC or ICU for an RSV-related illness. Using a detailed questionnaire, we collected information on risk factors, therapy requirements, length of stay in the IMC/ICU and hospital, and outcome.

RESULTS

Of the 577 cases reported during the study period, 90 were excluded because the patients did not fulfill the inclusion criteria; data were incomplete in another 25 cases (5%). Therefore, a total of 462 verified cases were eligible for analysis. At the time of hospital admission, only 31 patients (11%) were older than 12 months. Since RSV infection was not the main reason for IMC/ICU admission in 52% of these patients, we chose to exclude this subgroup from further analyses. Among the 431 infants aged < 12 months, the majority (77%) were former near term or full term (NT/FT) infants with a gestational age > or = 35 weeks without additional risk factors who were hospitalized at a median age of 1.5 months. Gestational age (GA) < 32 weeks, moderate to severe bronchopulmonary dysplasia (BPD), and congenital heart disease (CHD) were all associated with a significant risk increase for IMC/ICU admission (relative risk 14, 56, and 10, for GA < or = 32 weeks, BPD, and CHD, respectively). Compared with NT/FT infants, high-risk infants were hospitalized at an older age (except for infants with CHD), required more invasive and longer respiratory support, and had longer stays in the IMC/ICU and hospital.

CONCLUSIONS

In Switzerland, RSV infections lead to the IMC/ICU admission of approximately 1%-2% of each annual birth cohort. Although prematurity, BPD, and CHD are significant risk factors, non-pharmacological preventive strategies should not be restricted to these high-risk patients but also target young NT/FT infants since they constitute 77% of infants requiring IMC/ICU admission.

Prospective study of Human Bocavirus (HBoV) infection in a pediatric university hospital in Germany 2005/2006

Background

Human Bocavirus (HBoV), a new species of the genus parvovirus newly detected in 2005, seems to be a worldwide distributed pathogen among children with respiratory tract infection (prevalence 2%–18%). Recently published retrospective studies and one prospective birth cohort study suggest that HBoV-primary infection occurs in infants.

Methods

Prospective single center study over one winter season (November 2005–May 2006) with hospitalized children without age restriction using PCR-based diagnostic methods.

Results

HBoV DNA was detected in 11 (2.8%) of 389 nasopharyngeal aspirates from symptomatic hospitalized children (median age 9.0 months; range: 3–17 months). RSV, HMPV, HCoV, and Influenza B were detected in 13.9% (n = 54), 5.1% (n = 20), 2.6% (n = 10), and 1.8% (n = 7), respectively. There was no influenza A DNA detected in any of the specimens. The clinical diagnoses were acute wheezing (bronchitis) in four patients, radiologically confirmed pneumonia in six patients (55%) and croup syndrome in one patient. In five to six patients with pneumonia, HBoV was the only pathogen detected. While no patient had to be mechanically ventilated, 73% needed oxygen supplementation. In four (36.4%) patients at least one other viral pathogen was found (plus RSV n = 3; 27.3%; Norovirus n = 1; 9.1%).

Conclusion

HBoV causes severe respiratory tract infections in infants and young children. Its role as a copathogen and many other open questions has to be defined in further prospective studies.