Hospitalization for respiratory syncytial virus in the paediatric population in Spain

Clinical relevance of viral codetection in infants with respiratory syncytial virus bronchiolitis

INTRODUCTION

Respiratory syncytial virus (RSV) is the main cause of severe bronchiolitis, especially in infants. The aim of this study is to assess whether codetection of RSV and other respiratory viruses could affect the severity of this infection comparing with unique RSV detection.

METHODS

A prospective study from 2016 to 2019 including children under 2 years who were admitted in the Emergency Service of the Hospital Universitari Arnau de Vilanova de Lleida (Spain) was performed. Nasopharyngeal samples from all patients were sent to the laboratory for RSV real-time PCR detection (GeneXpert®). A multiplex PCR that detects other respiratory viruses was done in all RSV-positive samples. Patients'medical records were checked to collect clinical data (hospital length of stay, BROSJOD score, ICU admission, need for ventilatory support or transfer to a reference hospital). Patients were divided in two groups: infants with unique RSV detection and infants with viral codetection. Bivariant analyses were performed to analyze the data obtained.

RESULTS

During the period of study 437 RSV bronchiolitis were diagnosed. In 199 of them (177/437; 45,5%) another respiratory virus was detected concomitantly. Bivariant analyses do not show statistically significant differences between both groups.

CONCLUSIONS

Viral codetection in infants with RSV bronchiolitis is frequent. However, it does not seems to affect the severity of this infection.

Clinical and economic hospital burden of acute respiratory infection (BARI) due to respiratory syncytial virus in Spanish children, 2015-2018

Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory infection (ALRI) in children, causing frequent outpatient visits and hospitalizations. Our study aimed to describe the clinical and direct economic burden of ALRI hospitalizations related to RSV in children in Spain and the characteristics of patients and their episodes. In this retrospective study, ALRI hospitalizations in children aged < 5 years for 2015-2018 were reviewed using anonymized administrative public hospital discharge data from Spain. Three case definitions were considered: (a) RSV-specific; (b) RSV-specific and unspecified acute bronchiolitis (RSV-specific and bronchiolitis); and (c) RSV-specific and unspecified ALRI (RSV-specific and ALRI). The study reported a mean of 36,743 yearly admissions potentially due to RSV, resulting in a mean annual cost of €87.1 million. RSV-specific codes accounted for 39.2% of cases, unspecified acute bronchiolitis for 20.1%, and other unspecified ALRI codes for the remaining 40.6%. The mean hospitalization rate per 1,000 children was 55.5 in the first year of life, 16.0 in the second, and 5.4 between 24 and 59 months. A considerable proportion of cases occurred in children under two years old (> 80.4%) and even during the first year of life (> 61.7%). Otherwise healthy children accounted for 92.9% of hospitalizations and 83.3% of costs during the period. Children born preterm accounted for 1.3% of hospitalizations and 5.7% of costs. The findings revealed that RSV still contributes to a high burden on the Spanish health care system. Children under one year of age and otherwise healthy term infants accounted for most of the substantial clinical and economic burden of RSV. Current evidence potentially underestimates the true epidemiology and burden of severe RSV infection; thus, further studies focusing on the outpatient setting are needed.

The increasing age of respiratory syncytial virus-related hospitalisation during COVID-19 pandemic in Lyon was associated with reduced hospitalisation costs

BACKGROUND

Preventive measures applied during the COVID-19 pandemic have modified the age distribution, the clinical severity and the incidence of Respiratory Syncytial Virus (RSV) hospitalisations during the 2020/21 RSV season. The aim of the present study was to estimate the impact of these aspects on RSV-associated hospitalisations (RSVH) costs stratified by age group between pre-COVID-19 seasons and 2020/21 RSV season.

METHODS

We compared the incidence, the median costs, and total RSVH costs from the national health insurance perspective in children < 24 months of age during the COVID-19 period (2020/21 RSV season) with a pre-COVID-19 period (2014/17 RSV seasons). Children were born and hospitalised in the Lyon metropolitan area. RSVH costs were extracted from the French medical information system (Programme de Médicalisation des Systémes d'Information).

RESULTS

The RSVH-incidence rate per 1000 infants aged < 3 months decreased significantly from 4.6 (95 % CI [4.1; 5.2]) to 3.1 (95 % CI [2.4; 4.0]), and increased in older infants and children up to 24 months of age during the 2020/21 RSV season. Overall, RSVH costs for RSVH cases aged below 2 years old decreased by €201,770 (31 %) during 2020/21 RSV season compared to the mean pre-COVID-19 costs.

CONCLUSIONS

The sharp reduction in costs of RSVH in infants aged < 3 months outweighed the modest increase in costs observed in the 3-24 months age group. Therefore, conferring a temporal protection through passive immunisation to infants aged < 3 months should have a major impact on RSVH costs even if it results in an increase of RSVH in older children infected later in life. Nevertheless, stakeholders should be aware of this potential increase of RSVH in older age groups presenting with a wider range of disease to avoid any bias in estimating the cost-effectiveness of passive immunisation strategies.

Incidence of respiratory syncytial virus lower respiratory tract infections during the first 2 years of life: A prospective study across diverse global settings

Background

The true burden of lower respiratory tract infections (LRTIs) due to respiratory syncytial virus (RSV) remains unclear. This study aimed to provide more robust, multinational data on RSV-LRTI incidence and burden in the first 2 years of life.

Methods

This prospective, observational cohort study was conducted in Argentina, Bangladesh, Canada, Finland, Honduras, South Africa, Thailand, and United States. Children were followed for 24 months from birth. Suspected LRTIs were detected via active (through regular contacts) and passive surveillance. RSV and other viruses were detected from nasopharyngeal swabs using PCR-based methods.

Results

Of 2401 children, 206 (8.6%) had 227 episodes of RSV-LRTI. Incidence rates (IRs) of first episode of RSV-LRTI were 7.35 (95% confidence interval [CI], 5.88–9.08), 5.50 (95% CI, 4.21–7.07), and 2.87 (95% CI, 2.18–3.70) cases/100 person-years in children aged 0–5, 6–11, and 12–23 months. IRs for RSV-LRTI, severe RSV-LRTI, and RSV hospitalization tended to be higher among 0–5 month olds and in lower-income settings. RSV was detected for 40% of LRTIs in 0–2 month olds and for approximately 20% of LRTIs in older children. Other viruses were codetected in 29.2% of RSV-positive nasopharyngeal swabs.

Conclusions

A substantial burden of RSV-LRTI was observed across diverse settings, impacting the youngest infants the most.

Clinical Trials Registration. NCT01995175.

Year-to-year variation in attack rates could result in underpowered RSV vaccine efficacy trials

OBJECTIVE

Year-to-year variation of respiratory viruses may result in lower attack rates than expected. We aimed to illustrate the impact of year-to-year variation in attack rates on the likelihood of demonstrating vaccine efficacy (VE) .

STUDY DESIGN AND SETTING

We considered an individually randomized maternal vaccine trial against respiratory syncytial virus-associated hospitalisations (RSVH). For 10 RSVH per 1,000 infants, sample size to have 80% power for true VE of 50% and 70% was 9,846 and 4,424 participants. We reported power to show VE for varying attack rates, selected to reflect realistic year-to-year variation using observational studies. Eight scenarios including varying number of countries and seasons were developed to assess the influence of these trial parameters.

RESULTS

Including up to three seasons decreased the width of the interquartile range for power. Including more seasons concentrated statistical power closer to 80%. Least powered trials had higher statistical power with more seasons. In all scenarios, at least half of the trials had <80% power. For three-season trials, increasing the sample size by 10% reduced the percentage of underpowered trials to less than one-quarter of trials.

CONCLUSION

Year-to-year variation in RSV attack rates should be accounted for during trial design. Mitigation strategies include recruiting over more seasons, or adaptive trial designs.

Seasonality and coinfection of bronchiolitis: epidemiological specificity and consequences in terms of prophylaxis in tropical climate

OBJECTIVE

To describe the viruses involved, seasonality and coinfection in hospitalised children with suspected bronchiolitis.

METHODS

Over the period 1/07/2007 to 31/12/2008, all children hospitalised for bronchiolitis in the paediatric ward were prospectively included, and had respiratory syncytial virus (RSV) screenings. We retrospectively tested all samples for RSVA, RSVB, rhinovirus (RV), human metapneumovirus, parainfluenza 1, 2, 3, 4, influenza A and influenza B.

RESULTS

198 children were tested, and 23% were negative for all viruses. RSVA was predominant in 2008 (64% of all viruses) and RSVB in 2007 (66% of all viruses). RV was frequent during both seasons (24% of all viruses). Flu was not found during the study period. Virus distribution was similar regardless of season or age, and identical to typical patterns in temperate countries. Coinfections were less frequent than in temperate regions because respiratory virus seasons seem to be better separated. The bronchiolitis season started in August and finished in December with a peak in October.

CONCLUSION

The specific seasonality of bronchiolitis infection requires palivizumab prophylaxis starting in early July for high-risk infants.

Association of Age at First Severe Respiratory Syncytial Virus Disease With Subsequent Risk of Severe Asthma: A Population-Based Cohort Study

OBJECTIVE

In a population-based cohort study, we determined the association between the age at first severe respiratory syncytial virus (RSV) disease and subsequent asthma.

METHODS

Incidence rates and rate ratios of the first asthma-associated hospitalization after 2 years of age in children hospitalized for RSV disease at <3 months, 3 to <6 months, 6 to <12 months, and 12-24 months of age were calculated.

RESULTS

The incidence of asthma-associated hospitalization per 1000 child-years among children hospitalized for RSV disease at <3 months of age was 0.5 (95% confidence interval [CI], .2-.7); at 3 to <6 months of age, 0.9 (95% CI,.5-1.3); at 6 to <12 months of age, 2.0 (95% CI, 1.4-2.7); and at 12-24 months of age, 1.7 (95% CI, 1.0-2.5). The rate ratio of hospitalization for asthma was 2-7-fold greater among children hospitalized for RSV disease at ages ≥6 months than that among those hospitalized for RSV disease at ages 0 to <6 months.

CONCLUSIONS

Although the burden of RSV disease is highest in children aged <6 months, the burden of subsequent asthma is higher in children who develop RSV disease at ages ≥6 months.

Preventing respiratory syncytial virus infections in hospitalized children and adults: should we do better?

Objective

To compare the burden of nosocomial and community-acquired respiratory syncytial virus (RSV)-associated acute lower respiratory tract infections (ALRIs) in adult and pediatric patients concomitantly admitted to a French tertiary hospital, and to evaluate the effectiveness of existing infection control measures.

Patients and methods

We prospectively included all adult and pediatric patients admitted to Necker hospital (Paris) between October 2018 and February 2019 with a diagnosis of RSV-associated ALRI. We compared characteristics of ALRIs between patients with community-acquired versus nosocomial infections and, in each group, between children and adults.

Results

Community-acquired and nosocomial RSV-associated ALRIs were diagnosed in 229 and 11 inpatients, respectively. The burden of community-acquired infections was higher in children than in adults: 2.1% versus 0.2% of the total number of pediatric and adult inpatients, respectively (p < 0.0001); 4.2% versus 0.2% of the total number of hospitalization days in pediatric and adult units, respectively (p < 0.0001). Compared to inpatients with community-acquired ALRIs, those with nosocomial infections were more frequently adults (45.5% versus 2.6%, p = 0.0005) and subjects with at least one chronic complex condition (100.0% versus 41.0%, p < 0.0001). The total number of hospitalization days due to nosocomial ALRIs was higher in adults than in children (0.32% versus 0.11%, p < 0.0001).

Conclusions

Nosocomial RSV-associated ALRIs rarely occurred, suggesting a good effectiveness of our infection control strategy. However, the burden of nosocomial infection was higher in adults than in children, suggesting that education and training of healthcare personnel, patients and visitors about the risk of nosocomial RSV infections should be reinforced in adult wards.

Preventing Pediatric Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) infection in infants is a major cause of morbidity and mortality worldwide. Despite intense research efforts, safe and effective vaccines have remained elusive. Risk factors for the development of severe disease are well known, and those infants at highest risk are identified to receive RSV prophylaxis in the form of anti-RSV monoclonal antibody. Still, many other infant groups remain at risk and could benefit from an effective RSV prevention program. An explosion of clinic research activity is bringing unprecedented progress. Several of the most promising approaches currently being evaluated in clinical trials are reviewed. [Pediatr Ann. 2018;47(9):e371-e376.].

Ameliorating Effect of Dietary Xylitol on Human Respiratory Syncytial Virus (hRSV) Infection

Human respiratory syncytial virus (hRSV) is the most common cause of bronchiolitis and pneumonia in infants. The lack of proper prophylactics and therapeutics for controlling hRSV infection has been of great concern worldwide. Xylitol is a well-known sugar substitute and its effect against bacteria in the oral cavity is well known. However, little is known of its effect on viral infections. In this study, the effect of dietary xylitol on hRSV infection was investigated in a mouse model for the first time. Mice received xylitol for 14 d prior to virus challenge and for a further 3 d post challenge. Significantly larger reductions in lung virus titers were observed in the mice receiving xylitol than in the controls receiving phosphate-buffered saline (PBS). In addition, fewer CD3(+) and CD3(+)CD8(+) lymphocytes, whose numbers reflect inflammatory status, were recruited in the mice receiving xylitol. These results indicate that dietary xylitol can ameliorate hRSV infections and reduce inflammation-associated immune responses to hRSV infection.

Defining the Epidemiology and Burden of Severe Respiratory Syncytial Virus Infection Among Infants and Children in Western Countries

INTRODUCTION

The REGAL (RSV [respiratory syncytial virus] Evidence-a Geographical Archive of the Literature) series provides a comprehensive review of the published evidence in the field of RSV in Western countries over the last 20 years. This first of seven publications covers the epidemiology and burden of RSV infection.

METHODS

A systematic review was undertaken for articles published between Jan 1, 1995 and Dec 31, 2015 across PubMed, Embase, The Cochrane Library, and Clinicaltrials.gov. Studies reporting data for hospital visits/admissions for RSV infection among children (≤18 years of age), as well as studies reporting RSV-associated morbidity, mortality, and risk factors were included. Study quality and strength of evidence (SOE) were graded using recognized criteria.

RESULT

2315 studies were identified of which 98 were included. RSV was associated with 12-63% of all acute respiratory infections (ARIs) and 19-81% of all viral ARIs causing hospitalizations in children (high SOE). Annual RSV hospitalization (RSVH) rates increased with decreasing age and varied by a factor of 2-3 across seasons (high SOE). Studies were conflicting on whether the incidence of RSVH has increased, decreased, or remained stable over the last 20 years (moderate SOE). Length of hospital stay ranged from 2 to 11 days, with 2-12% of cases requiring intensive care unit admission (moderate SOE). Case-fatality rates were <0.5% (moderate SOE). Risk factors associated with RSVH included: male sex; age <6 months; birth during the first half of the RSV season; crowding/siblings; and day-care exposure (high SOE).

CONCLUSION

RSV infection remains a major burden on Western healthcare systems and has been associated with significant morbidity. Further studies focusing on the epidemiology of RSV infection (particularly in the outpatient setting), the impact of co-infection, better estimates of case-fatality rates and associated risk factors (all currently moderate/low SOE) are needed to determine the true burden of disease.

FUNDING

Abbvie.

Palivizumab for prophylaxis against respiratory syncytial virus infection in children with cystic fibrosis

BACKGROUND

Respiratory syncytial virus infection causes acute lung infection in infants and young children worldwide, resulting in considerable morbidity and mortality. Children with cystic fibrosis are prone to recurrent lung inflammation, bacterial colonisation and subsequent chronic airway disease, putting them at risk for severe respiratory syncytial virus infections requiring intensive care and respiratory support. No treatment currently exists, hence prevention is important. Palivizumab is effective in reducing respiratory syncytial virus hospitalisation rates and is recommended for prophylaxis in high-risk children with other conditions. It is unclear if palivizumab can prevent respiratory syncytial virus hospitalisations and intensive care unit admissions in children with cystic fibrosis. This is an update of a previously published review.

OBJECTIVES

To determine the efficacy and safety of palivizumab (Synagis(®)) compared with placebo, no prophylaxis or other prophylaxis, in preventing hospitalisation and mortality from respiratory syncytial virus infection in children with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register and scanned references of the eligible study and related reviews.Date of last search: 05 May 2016.

SELECTION CRITERIA

Randomised and quasi-randomised studies.

DATA COLLECTION AND ANALYSIS

The authors independently extracted data and assessed risk of bias.

MAIN RESULTS

One study (186 infants up to two years old) comparing five monthly doses of palivizumab (N = 92) to placebo (N = 94) over one respiratory syncytial virus season was identified and met our inclusion criteria. We judged there to be a low risk of bias with respect to the concealment of the randomization schedule (although it was not clear how this was generated) and to blinding of participants and study personnel. There is also a low risk of bias with regards to incomplete outcome data. However, we judged there to be a high risk of bias from selective reporting (summary statements presented but no data) and the fact that this industry-supported study has not been published as a full report in a peer-reviewed journal.At six months follow-up, one participant in each group was hospitalised due to respiratory syncytial virus; there were no deaths in either group. In the palivizumab and placebo groups, 86 and 90 children experienced any adverse event, while five and four children had related adverse events respectively. Nineteeen children receiving palivizumab and 16 receiving placebo suffered serious adverse events; one participant receiving palivizumab discontinued due to this. At 12 months follow-up, there were no significant differences between groups in number of Pseudomonas bacterial colonisations or change in weight-to-height ratio.

AUTHORS' CONCLUSIONS

We identified one randomised controlled trial comparing five monthly doses of palivizumab to placebo in infants up to two years old with cystic fibrosis. While the overall incidence of adverse events was similar in both groups, it is not possible to draw firm conclusions on the safety and tolerability of respiratory syncytial virus prophylaxis with palivizumab in infants with cystic fibrosis. Six months after treatment, the authors reported no clinically meaningful differences in outcomes. Additional randomised studies are needed to establish the safety and efficacy of palivizumab in children with cystic fibrosis.

Respiratory Syncytial Virus-associated hospitalization in premature infants who did not receive palivizumab prophylaxis in Italy: a retrospective analysis from the Osservatorio Study

BACKGROUND

Due to different social and epidemiological factors, the eligibility criteria to receive palivizumab prophylaxis may be different between countries, especially in "otherwise healthy" late preterm infants.

METHODS

We analyzed an Italian database of young children referred to emergency departments for acute lower respiratory tract infection (ALRI) during the RSV season over a four year period, when the use of palivizumab as prophylaxis for RSV disease was not widespread in premature infants. The demographic and environmental characteristics and the RSV positivity (RSV(+)) in hospitalized and not-hospitalized patients were compared. In the data analysis we divided children according to their chronologic age (age) and their week gestational age (wGA).

RESULTS

Out of the 100 children evaluated, 68 were infants (≤12 month-age): 7.5 and 20.6 % were in the <29 and 29- < 32 wGA groups respectively, and 72.0 % in the 32- < 35 wGA group. Positive hospitalized-to-not-hospitalized ratios were found in all three wGA groups, progressively decreasing (from 4.0 to 1.2), with increasing wGA (p = 0.35). The percentage of hospitalized infants that were also RSV(+) was also progressively decreasing (from 40.0 to 28.6 % and 18.4 %) with increasing wGA (p = 0.43). In the >12 month-age group (N = 32), there was positive hospitalized-to-not-hospitalized ratio only in the <29 wGA group with a low RSV(+) frequency (<29 %) in all wGA groups. In the ≤12 month-age group, 41 infants were evaluated with a ≤6 month-age and 27 with a >6-12 month-age. A positive hospitalized-to-not-hospitalized ratios was found in all wGA groups in ≤6 month-age infants, despite a low RSV(+) frequency in the 29- < 32 and 32- < 35 wGA group. In the >6-12 month-age group, all infants with a <29 and 29- < 32 wGA were hospitalized with a relatively high RSV(+) frequency whilst the 32- < 35 wGA group showed a negative hospitalized-to-not-hospitalized ratio with a lower RSV(+) frequency.

CONCLUSIONS

The hospitalized-to-not-hospitalized ratios and RSV(+) frequency in the first 12 months of age in infants born prematurely confirm the vulnerability of these children for clinically important RSV infection, most notably in the <32 wGA category.

[High flow nasal cannula oxygen therapy in the treatment of acute bronchiolitis in neonates]

OBJECTIVE

To determine whether the availability of heated humidified high-flow nasal cannula (HFNC) therapy was associated with a decrease in need for mechanical ventilation in neonates hospitalised with acute bronchiolitis.

METHODS

A combined retrospective and prospective (ambispective) cohort study was performed in a type II-B Neonatal Unit, including hospitalised neonates with acute bronchiolitis after the introduction of HFNC (HFNC-period; October 2011-April 2015). They were compared with a historical cohort prior to the availability of this technique (pre-HFNC; January 2008-May 2011). The need for mechanical ventilation between the two study groups was analysed. Clinical parameters and technique-related complications were evaluated in neonates treated with HFNC.

RESULTS

A total of 112 neonates were included, 56 after the introduction of HFNC and 56 from the period before the introduction of HFNC. None of patients in the HFNC-period required intubation, compared with 3.6% of the patients in the pre-HFNC group. The availability of HFNC resulted in a significant decrease in the need for non-invasive mechanical ventilation (30.4% vs 10.7%; P=.01), with a relative risk (RR) of .353 (95% CI; .150-.829), an absolute risk reduction (ARR) of 19.6% (95% CI; 5.13 - 34.2), yielding a NNT of 5. In the HFNC-period, 22 patients received high flow therapy, and 22.7% (95% CI; 7.8 to 45.4) required non-invasive ventilation. Treatment with HFNC was associated with a significant decrease in heart rate (P=.03), respiratory rate (P=.01), and an improvement in the Wood-Downes Férres score (P=.00). No adverse effects were observed.

CONCLUSIONS

The availability of HFNC reduces the need for non-invasive mechanical ventilation, allowing a safe and effective medical management of neonates with acute bronchiolitis.

Population-based Analysis of Bronchiolitis Epidemiology in Valencia, Spain

BACKGROUND

There is a lack of European epidemiologic population-based studies on bronchiolitis and respiratory syncytial virus (RSV) bronchiolitis including both hospitalizations and primary care attendance.

METHODS

A retrospective cohort of all children born between 2009 and 2012 was followed from birth to 2 years of age using population and health databases. We searched for global bronchiolitis (International Classification of Diseases, 9th revision, Clinical Modification codes 466.1, 466.11 and 466.19) and RSV bronchiolitis (code 466.11 and code 466.19 with positive RSV test) in the first appearance either in primary care or in hospitalization databases. A preterm subcohort (International Classification of Diseases, 9th revision, Clinical Modification codes 765) was also analyzed.

RESULTS

The cohort consisted of 198,223 children of whom 41,479 were diagnosed of bronchiolitis (incidence rate 16.4/100 children <2 years per year). Of those, 5390 were hospitalized with the majority of hospitalizations occurring at <6 months of age (incidence rate of 5.2/100 children <6 months per year) and 3106 of the hospitalizations were RSV positive (incidence rate 3.2/100 children <6 months per year). RSV hospitalizations were 26% longer than non-RSV. In preterm infants, hospitalization incidence was more than double, and the mean length of hospitalization was 29% longer.

CONCLUSIONS

Most (87%) bronchiolitis cases are managed in primary care offices. Approximately 2 out of every 10 children <2 are diagnosed of bronchiolitis, 3 out of every 100 are hospitalized and 1.6 out of every 100 are hospitalized with RSV bronchiolitis in our cohort. Infants between 2 and 10 weeks constitute a risk group for severe bronchiolitis.

Epinephrine Improves the Efficacy of Nebulized Hypertonic Saline in Moderate Bronchiolitis: A Randomised Clinical Trial

Background and Aims

There is no evidence that the epinephrine-3% hypertonic saline combination is more effective than 3% hypertonic saline alone for treating infants hospitalized with acute bronchiolitis. We evaluated the efficacy of nebulized epinephrine in 3% hypertonic saline.

Patients and Methods

We performed a randomized, double-blind, placebo-controlled clinical trial in 208 infants hospitalized with acute moderate bronchiolitis. Infants were randomly assigned to receive nebulized 3% hypertonic saline with either 3 mL of epinephrine or 3 mL of placebo, administered every four hours. The primary outcome measure was the length of hospital stay.

Results

A total of 185 infants were analyzed: 94 in the epinephrine plus 3% hypertonic saline group and 91 in the placebo plus 3% hypertonic saline group. Baseline demographic and clinical characteristics were similar in both groups. Length of hospital stay was significantly reduced in the epinephrine group as compared with the placebo group (3.94 ±1.88 days vs. 4.82 ±2.30 days, P = 0.011). Disease severity also decreased significantly earlier in the epinephrine group (P = 0.029 and P = 0.036 on days 3 and 5, respectively).

Conclusions

In our setting, nebulized epinephrine in 3% hypertonic saline significantly shortens hospital stay in hospitalized infants with acute moderate bronchiolitis compared to 3% hypertonic saline alone, and improves the clinical scores of severity from the third day of treatment, but not before.

Trial Registration

EudraCT 2009-016042-57

Respiratory Syncytial Virus Bronchiolitis in Children up to 5 Years of Age in Spain: Epidemiology and Comorbidities: An Observational Study

This epidemiological survey in Spain estimates the burden of respiratory syncytial virus (RSV) infection in children up to 5 year of age during a 15-year period (1997-2011). Observational retrospective survey was conducted by reviewing data of the National Surveillance System for Hospital Data, including >98% of Spanish hospitals. All hospitalizations related to RSV infection for children up to 5 years, reported during 1997-2011 period, were analyzed. Codes were selected by using the International Classification of Diseases 9th Clinical Modification 466.0-466.19, 480.1, and 079.6. A total of 326,175 and 286,007 hospital discharges for children up to 5 and 2 years of age were reported during the study period. The annual incidence was 1072 and 2413 patients per 100,000, respectively. The average length of hospital stay was 5.7 (standard deviation 8.2) days. Four hundred forty-six deaths were reported; of those, 403 occurred in children <2 years and 355 (80%) occurred in children <12 months of age. Hospitalization and mortality rates were significantly higher in boys and decrease significantly with age. The higher rate of hospitalization and mortality rates were found in the first year of life. Annual average cost for National Health Care System was € 47 M with a mean hospitalization cost of €2162. The average length of hospitalization and costs were significantly higher in high-risk children. RSV infections in children up to 5 year of age still pose a significant health threat in Spain, especially in the infants. The development of preventive, diagnostic, and therapeutic guidelines focused in children with comorbidities may help reduce the hospital and economic burden of the disease.

Modelling the seasonal epidemics of respiratory syncytial virus in young children

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of paediatric morbidity. Mathematical models can be used to characterise annual RSV seasonal epidemics and are a valuable tool to assess the impact of future vaccines.

OBJECTIVES

Construct a mathematical model of seasonal epidemics of RSV and by fitting to a population-level RSV dataset, obtain a better understanding of RSV transmission dynamics.

METHODS

We obtained an extensive dataset of weekly RSV testing data in children aged less than 2 years, 2000-2005, for a birth cohort of 245,249 children through linkage of laboratory and birth record datasets. We constructed a seasonally forced compartmental age-structured Susceptible-Exposed-Infectious-Recovered-Susceptible (SEIRS) mathematical model to fit to the seasonal curves of positive RSV detections using the Nelder-Mead method.

RESULTS

From 15,830 specimens, 3,394 were positive for RSV. RSV detections exhibited a distinct biennial seasonal pattern with alternating sized peaks in winter months. Our SEIRS model accurately mimicked the observed data with alternating sized peaks using disease parameter values that remained constant across the 6 years of data. Variations in the duration of immunity and recovery periods were explored. The best fit to the data minimising the residual sum of errors was a model using estimates based on previous models in the literature for the infectious period and a slightly lower estimate for the immunity period.

CONCLUSIONS

Our age-structured model based on routinely collected population laboratory data accurately captures the observed seasonal epidemic curves. The compartmental SEIRS model, based on several assumptions, now provides a validated base model. Ranges for the disease parameters in the model that could replicate the patterns in the data were identified. Areas for future model developments include fitting climatic variables to the seasonal parameter, allowing parameters to vary according to age and implementing a newborn vaccination program to predict the effect on RSV incidence.

Palivizumab for prophylaxis against respiratory syncytial virus infection in children with cystic fibrosis

BACKGROUND

Respiratory syncytial virus infection causes acute lung infection in infants and young children worldwide, resulting in considerable morbidity and mortality. Children with cystic fibrosis are prone to recurrent lung inflammation, bacterial colonisation and subsequent chronic airway disease, putting them at risk for severe respiratory syncytial virus infections requiring intensive care and respiratory support. No treatment currently exists, hence prevention is important. Palivizumab is effective in reducing respiratory syncytial virus hospitalisation rates and is recommended for prophylaxis in high-risk children with other conditions. It is unclear if palivizumab can prevent respiratory syncytial virus hospitalisations and intensive care unit admissions in children with cystic fibrosis.

OBJECTIVES

To determine the efficacy and safety of palivizumab (Synagis(®)) compared with placebo, no prophylaxis or other prophylaxis, in preventing hospitalisation and mortality from respiratory syncytial virus infection in children with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register and scanned references of the eligible study and related reviews.Date of last search: 17 March 2014.

SELECTION CRITERIA

Randomised and quasi-randomised studies.

DATA COLLECTION AND ANALYSIS

The authors independently extracted data and assessed risk of bias.

MAIN RESULTS

One study (186 infants up to two years old) comparing five monthly doses of palivizumab (N = 92) to placebo (N = 94) over one respiratory syncytial virus season was identified and met our inclusion criteria. We judged there to be a low risk of bias with respect to the concealment of the randomization schedule (although it was not clear how this was generated) and to blinding of participants and study personnel. There is also a low risk of bias with regards to incomplete outcome data. However, we judged there to be a high risk of bias from selective reporting (summary statements presented but no data) and the fact that this industry-supported study has not been published as a full report in a peer-reviewed journal.At six months follow-up, one participant in each group was hospitalised due to respiratory syncytial virus; there were no deaths in either group. In the palivizumab and placebo groups, 86 and 90 children experienced any adverse event, while five and four children had related adverse events respectively. Nineteeen children receiving palivizumab and 16 receiving placebo suffered serious adverse events; one participant receiving palivizumab discontinued due to this. At 12 months follow-up, there were no significant differences between groups in number of Pseudomonas bacterial colonisations or change in weight-to-height ratio.

AUTHORS' CONCLUSIONS

We identified one randomised controlled trial comparing five monthly doses of palivizumab to placebo in infants up to two years old with cystic fibrosis. While the overall incidence of adverse events was similar in both groups, it is not possible to draw firm conclusions on the safety and tolerability of respiratory syncytial virus prophylaxis with palivizumab in infants with cystic fibrosis. Six months after treatment, the authors reported no clinically meaningful differences in outcomes. Additional randomised studies are needed to establish the safety and efficacy of palivizumab in children with cystic fibrosis.

Respiratory syncytial virus infection in Guatemala, 2007-2012

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of acute respiratory illness (ARI). Little is known about RSV disease among older children and adults in Central America.

METHODS

Prospective surveillance for ARI among hospital patients and clinic patients was conducted in Guatemala during 2007-2012. Nasopharyngeal and oropharyngeal swab specimens were tested for RSV, using real-time reverse-transcription polymerase chain reaction.

RESULTS

Of 6287 hospitalizations and 2565 clinic visits for ARI, 24% and 12%, respectively, yielded RSV-positive test results. The incidence of RSV-positive hospitalization for ARI was 5.8 cases/10 000 persons per year and was highest among infants aged <6 months (208 cases/10 000 persons per year); among adults, the greatest incidence was observed among those aged ≥ 65 years (2.9 cases/10 000 persons per year). The incidence of RSV-positive clinic visitation for ARI was 32 cases/10 000 persons per year and was highest among infants aged 6-23 months (186 cases/10 000 persons per year). Among RSV-positive hospital patients with ARI, underlying cardiovascular disease was associated with death, moribund discharge, intensive care unit admission, or mechanical ventilation (odds ratio, 4.1; 95% confidence interval, 1.9-8.8). The case-fatality proportion among RSV-positive hospital patients with ARI was higher for those aged ≥ 5 years than for those aged <5 years (13% vs 3%; P < .001).

CONCLUSIONS

The incidences of RSV-associated hospitalization and clinic visitation for ARI were highest among young children, but a substantial burden of ARI due to RSV was observed among older children and adults.

Rationale for full-season dosing for passive antibody prophylaxis of respiratory syncytial virus

Palivizumab monthly injections throughout the RSV season prevent severe respiratory syncytial virus (RSV) disease in preterm infants ≤ 35 wGA. However, some RSV guidelines currently recommend stopping palivizumab after 3 months of age in the midst of the RSV season. This article evaluates the need for full-season dosing by reviewing the pharmacokinetic properties of palivizumab and RSV hospitalization (RSVH) risk as a function of chronologic age. Precise human palivizumab protective levels are not established. Clinical trials show significant interpatient variability in palivizumab serum trough concentrations. Partial season dosing is associated with increased risk of RSVH. For late-preterm infants, data suggest that the risk of RSVH remains elevated through at least 6 months of age. Monthly, full-season palivizumab dosing provides the only empirically proven protection from RSVH. In conclusion, late-preterm infants are at significant risk for RSVH through at least 6 months of age and would benefit from dosing throughout the RSV season.

Respiratory syncytial virus--a comprehensive review

Respiratory syncytial virus (RSV) is amongst the most important pathogenic infections of childhood and is associated with significant morbidity and mortality. Although there have been extensive studies of epidemiology, clinical manifestations, diagnostic techniques, animal models and the immunobiology of infection, there is not yet a convincing and safe vaccine available. The major histopathologic characteristics of RSV infection are acute bronchiolitis, mucosal and submucosal edema, and luminal occlusion by cellular debris of sloughed epithelial cells mixed with macrophages, strands of fibrin, and some mucin. There is a single RSV serotype with two major antigenic subgroups, A and B. Strains of both subtypes often co-circulate, but usually one subtype predominates. In temperate climates, RSV infections reflect a distinct seasonality with onset in late fall or early winter. It is believed that most children will experience at least one RSV infection by the age of 2 years. There are several key animal models of RSV. These include a model in mice and, more importantly, a bovine model; the latter reflects distinct similarity to the human disease. Importantly, the prevalence of asthma is significantly higher amongst children who are hospitalized with RSV in infancy or early childhood. However, there have been only limited investigations of candidate genes that have the potential to explain this increase in susceptibility. An atopic predisposition appears to predispose to subsequent development of asthma and it is likely that subsequent development of asthma is secondary to the pathogenic inflammatory response involving cytokines, chemokines and their cognate receptors. Numerous approaches to the development of RSV vaccines are being evaluated, as are the use of newer antiviral agents to mitigate disease. There is also significant attention being placed on the potential impact of co-infection and defining the natural history of RSV. Clearly, more research is required to define the relationships between RSV bronchiolitis, other viral induced inflammatory responses, and asthma.

Respiratory syncytial virus-associated hospitalizations among children less than 24 months of age

BACKGROUND

Respiratory syncytial virus (RSV) infection is a leading cause of hospitalization among infants. However, estimates of the RSV hospitalization burden have varied, and precision has been limited by the use of age strata grouped in blocks of 6 to ≥ 12 months.

METHODS

We analyzed data from a 5-year, prospective, population-based surveillance for young children who were hospitalized with laboratory-confirmed (reverse-transcriptase polymerase chain reaction) RSV acute respiratory illness (ARI) during October through March 2000-2005. The total population at risk was stratified by month of age by birth certificate information to yield hospitalization rates.

RESULTS

There were 559 (26%) RSV-infected children among the 2149 enrolled children hospitalized with ARI (85% of all eligible children with ARI). The average RSV hospitalization rate was 5.2 per 1000 children <24 months old. The highest age-specific rate was in infants 1 month old (25.9 per 1000 children). Infants ≤ 2 months of age, who comprised 44% of RSV-hospitalized children, had a hospitalization rate of 17.9 per 1000 children. Most children (79%) were previously healthy. Very preterm infants (<30 weeks' gestation) accounted for only 3% of RSV cases but had RSV hospitalization rates 3 times that of term infants.

CONCLUSIONS

Young infants, especially those who were 1 month old, were at greatest risk of RSV hospitalization. Four-fifths of RSV-hospitalized infants were previously healthy. To substantially reduce the burden of RSV hospitalizations, effective general preventive strategies will be required for all young infants, not just those with risk factors.

Palivizumab for prophylaxis against respiratory syncytial virus infection in children with cystic fibrosis

BACKGROUND

Respiratory syncytial virus infection causes acute lung infection in infants and young children worldwide, resulting in considerable morbidity and mortality. Children with cystic fibrosis are prone to recurrent lung inflammation, bacterial colonisation and subsequent chronic airway disease, putting them at risk for severe respiratory syncytial virus infections requiring intensive care and respiratory support. No treatment currently exists, hence prevention is important. Palivizumab is effective in reducing respiratory syncytial virus hospitalisation rates and is recommended for prophylaxis in high-risk children with other conditions. It is unclear if palivizumab can prevent respiratory syncytial virus hospitalisations and intensive care unit admissions in children with cystic fibrosis.

OBJECTIVES

To determine the efficacy and safety of palivizumab (Synagis(®)) compared with placebo, no prophylaxis or other prophylaxis, in preventing hospitalisation and mortality from respiratory syncytial virus infection in children with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register and scanned references of the eligible study and related reviews.Date of last search: 11 October 2012.

SELECTION CRITERIA

Randomised and quasi-randomised studies.

DATA COLLECTION AND ANALYSIS

The authors independently extracted data and assessed risk of bias.

MAIN RESULTS

One study (186 infants up to two years old) comparing five monthly doses of palivizumab (N = 92) to placebo (N = 94) over one respiratory syncytial virus season was identified and met our inclusion criteria. At six months follow-up, one participant in each group was hospitalised due to respiratory syncytial virus; there were no deaths in either group. In the palivizumab and placebo groups, 86 and 90 children experienced any adverse event, while five and four children had related adverse events respectively. Nineteeen children receiving palivizumab and 16 receiving placebo suffered serious adverse events; one participant receiving palivizumab discontinued due to this. At 12 months follow-up, there were no significant differences between groups in number of Pseudomonas bacterial colonisations or change in weight-to-height ratio.

AUTHORS' CONCLUSIONS

We identified one randomised controlled trial comparing five monthly doses of palivizumab to placebo in infants up to two years old with cystic fibrosis. While the overall incidence of adverse events was similar in both groups, it is not possible to draw firm conclusions on the safety and tolerability of respiratory syncytial virus prophylaxis with palivizumab in infants with cystic fibrosis. Six months after treatment, the authors reported no clinically meaningful differences in outcomes. Additional randomised studies are needed to establish the safety and efficacy of palivizumab in children with cystic fibrosis.

The epidemiology and clinical characteristics of young children hospitalized with respiratory syncytial virus infections in Guatemala (2007-2010)

BACKGROUND

There have been few population-based studies from Central America on respiratory syncytial virus (RSV) infections in young children. We report population-based incidence rates and describe epidemiological and clinical characteristics of children <5 years old hospitalized with RSV infections in Guatemala.

METHODS

Prospective, active hospital-based surveillance for acute respiratory infections in children <5 years old was conducted at 3 hospitals in Guatemala from November 2007 through July 2010. RSV hospitalization rates were calculated for areas where the catchment population could be defined. Comparisons were made between children who were RSV-positive and RSV-negative.

RESULTS

RSV was detected in 549 (25%) of enrolled children. Overall, annual rates of RSV hospitalizations ranged from 5.9 to 45.9 and 2.0 to 13.7 per 1000 children <1 year old and <5 years old, respectively, but varied by location and calendar year. Rates generally decreased with age--children <6 months had rates up to 30 times higher than older children, but children >12 months old still had rates up to 5.5 per 1000 per year and accounted for 42% of deaths. Children with RSV infections were more likely to have signs of respiratory distress (85% versus 63%, P < 0.001) compared with those without RSV infections, but case fatality ratios were similar (3-4%).

CONCLUSIONS

The large burden and severity of RSV infections in young Guatemalan children is similar in magnitude and age distribution to RSV disease burdens found in other developing countries and suggests that this population would benefit from prevention strategies, including vaccines against RSV that are currently under development.

Global and regional burden of hospital admissions for severe acute lower respiratory infections in young children in 2010: a systematic analysis

BACKGROUND

The annual number of hospital admissions and in-hospital deaths due to severe acute lower respiratory infections (ALRI) in young children worldwide is unknown. We aimed to estimate the incidence of admissions and deaths for such infections in children younger than 5 years in 2010.

METHODS

We estimated the incidence of admissions for severe and very severe ALRI in children younger than 5 years, stratified by age and region, with data from a systematic review of studies published between Jan 1, 1990, and March 31, 2012, and from 28 unpublished population-based studies. We applied these incidence estimates to population estimates for 2010, to calculate the global and regional burden in children admitted with severe ALRI in that year. We estimated in-hospital mortality due to severe and very severe ALRI by combining incidence estimates with case fatality ratios from hospital-based studies.

FINDINGS

We identified 89 eligible studies and estimated that in 2010, 11·9 million (95% CI 10·3-13·9 million) episodes of severe and 3·0 million (2·1-4·2 million) episodes of very severe ALRI resulted in hospital admissions in young children worldwide. Incidence was higher in boys than in girls, the sex disparity being greatest in South Asian studies. On the basis of data from 37 hospital studies reporting case fatality ratios for severe ALRI, we estimated that roughly 265,000 (95% CI 160,000-450,000) in-hospital deaths took place in young children, with 99% of these deaths in developing countries. Therefore, the data suggest that although 62% of children with severe ALRI are treated in hospitals, 81% of deaths happen outside hospitals.

INTERPRETATION

Severe ALRI is a substantial burden on health services worldwide and a major cause of hospital referral and admission in young children. Improved hospital access and reduced inequities, such as those related to sex and rural status, could substantially decrease mortality related to such infection. Community-based management of severe disease could be an important complementary strategy to reduce pneumonia mortality and health inequities.

FUNDING

WHO.

[Epidemiology, clinical features and medical interventions in children hospitalized for bronchiolitis]

OBJECTIVES

To describe the epidemiology, clinical characteristics and treatments prescribed in children with bronchiolitis admitted to our hospital.

MATERIAL AND METHODS

Observational, descriptive and prospective study of children younger than 18 months, admitted to Hospital Virgen de la Arrixaca of Murcia (Spain), with the diagnosis of bronchiolitis, during the season of maximum incidence (December 2008-April 2009).

RESULTS

A total of 235 infants were admitted, of whom 78.7% of them were aged 5 months or less. We found a positive correlation between the number of cigarettes smoked by their mothers during pregnancy and the number of hospitalization and oxygen therapy days. Children whose mothers were smokers at the time of their admission needed a greater number of oxygen therapy days. Also infants who were not breastfed needed oxygen therapy during more days. Just under one quarter (23.8%) of them had underlying diseases, with prematurity being the most frequent and a risk factor for the ongoing of oxygen therapy and hospital stay. The use of diagnostic tests, bronchodilators, corticosteroids and antibiotics was high. The onset of high temperature was associated with an increased use of antibiotics in outside and inside the hospital setting. An abnormal chest X-ray or a raised C-reactive protein was associated with a higher use of antibiotics. Respiratory Syncytial virus (RSV) was the main aetiological agent, followed by Rhinovirus, Bocavirus, Adenovirus and Metapneumovirus

CONCLUSIONS

The majority of hospital admissions due to bronchiolitis took place during the first months of life. Infants whose mothers smoked during pregnancy had a worse clinical outcome. Despite the availability of clinical practice guidelines in our area, the use of diagnostic tests and pharmacological treatment was high.

Palivizumab for prophylaxis against respiratory syncytial virus infection in children with cystic fibrosis

BACKGROUND

Respiratory syncytial virus infection causes acute lung infection in infants and young children worldwide, resulting in considerable morbidity and mortality. Children with cystic fibrosis are prone to recurrent lung inflammation, bacterial colonisation and subsequent chronic airway disease, putting them at risk for severe respiratory syncytial virus infections requiring intensive care and respiratory support. No treatment currently exists, hence prevention is important. Palivizumab is effective in reducing respiratory syncytial virus hospitalisation rates and is recommended for prophylaxis in high-risk children with other conditions. It is unclear if palivizumab can prevent respiratory syncytial virus hospitalisations and intensive care unit admissions in children with cystic fibrosis.

OBJECTIVES

To determine the efficacy and safety of palivizumab (Synagis(®)) compared with placebo, no prophylaxis or other prophylaxis, in preventing hospitalisation and mortality from respiratory syncytial virus infection in children with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register and scanned references of the eligible study and related reviews.Date of last search: 25 October 2011.

SELECTION CRITERIA

Randomised and quasi-randomised studies.

DATA COLLECTION AND ANALYSIS

The authors independently extracted data and assessed risk of bias.

MAIN RESULTS

One study (186 infants up to two years old) comparing five monthly doses of palivizumab (N = 92) to placebo (N = 94) over one respiratory syncytial virus season was identified and met our inclusion criteria. At six months follow-up, one participant in each group was hospitalised due to respiratory syncytial virus; there were no deaths in either group. In the palivizumab and placebo groups, 86 and 90 children experienced any adverse event, while 5 and 4 children had related adverse events respectively. Nineteeen children receiving palivizumab and 16 receiving placebo suffered serious adverse events; one participant receiving palivizumab discontinued due to this. At 12 months follow-up, there were no significant differences between groups in number of Pseudomonas bacterial colonisations or change in weight-to-height ratio.

AUTHORS' CONCLUSIONS

We identified one randomised controlled trial comparing five monthly doses of palivizumab to placebo in infants up to two years old with cystic fibrosis. While the overall incidence of adverse events was similar in both groups, it is not possible to draw conclusions on the safety and tolerability of respiratory syncytial virus prophylaxis with palivizumab in infants with cystic fibrosis because the trial did not specify how adverse events were classified. Six months after treatment, the authors reported no clinically meaningful differences in outcomes; however no data were provided. Additional randomised studies are needed to establish the safety and efficacy of palivizumab in children with cystic fibrosis.

Ten years of global evolution of the human respiratory syncytial virus BA genotype with a 60-nucleotide duplication in the G protein gene

The emergence of natural isolates of human respiratory syncytial virus group B (HRSV-B) with a 60-nucleotide (nt) duplication in the G protein gene in Buenos Aires, Argentina, in 1999 (A. Trento et al., J. Gen. Virol. 84:3115-3120, 2003) and their dissemination worldwide allowed us to use the duplicated segment as a natural tag to examine in detail the evolution of HRSV during propagation in its natural host. Viruses with the duplicated segment were all clustered in a new genotype, named BA (A. Trento et al., J. Virol. 80:975-984, 2006). To obtain information about the prevalence of these viruses in Spain, we tested for the presence of the duplicated segment in positive HRSV-B clinical samples collected at the Severo Ochoa Hospital (Madrid) during 12 consecutive epidemics (1996-1997 to 2007-2008). Viruses with the 60-nt duplication were found in 61 samples, with a high prevalence relative to the rest of B genotypes in the most recent seasons. Global phylogenetic and demographic analysis of all G sequences containing the duplication, collected across five continents up until April 2009, revealed that the prevalence of the BA genotype increased gradually until 2004-2005, despite its rapid dissemination worldwide. After that date and coinciding with a bottleneck effect on the population size, a relatively new BA lineage (BA-IV) replaced all other group B viruses, suggesting further adaptation of the BA genotype to its natural host.

Global burden of acute lower respiratory infections due to respiratory syncytial virus in young children: a systematic review and meta-analysis

BACKGROUND

The global burden of disease attributable to respiratory syncytial virus (RSV) remains unknown. We aimed to estimate the global incidence of and mortality from episodes of acute lower respiratory infection (ALRI) due to RSV in children younger than 5 years in 2005.

METHODS

We estimated the incidence of RSV-associated ALRI in children younger than 5 years, stratified by age, using data from a systematic review of studies published between January, 1995, and June, 2009, and ten unpublished population-based studies. We estimated possible boundaries for RSV-associated ALRI mortality by combining case fatality ratios with incidence estimates from hospital-based reports from published and unpublished studies and identifying studies with population-based data for RSV seasonality and monthly ALRI mortality.

FINDINGS

In 2005, an estimated 33.8 (95% CI 19.3-46.2) million new episodes of RSV-associated ALRI occurred worldwide in children younger than 5 years (22% of ALRI episodes), with at least 3.4 (2.8-4.3) million episodes representing severe RSV-associated ALRI necessitating hospital admission. We estimated that 66 000-199 000 children younger than 5 years died from RSV-associated ALRI in 2005, with 99% of these deaths occurring in developing countries. Incidence and mortality can vary substantially from year to year in any one setting.

INTERPRETATION

Globally, RSV is the most common cause of childhood ALRI and a major cause of admission to hospital as a result of severe ALRI. Mortality data suggest that RSV is an important cause of death in childhood from ALRI, after pneumococcal pneumonia and Haemophilus influenzae type b. The development of novel prevention and treatment strategies should be accelerated as a priority.

FUNDING

WHO; Bill & Melinda Gates Foundation.

[Consensus conference on acute bronchiolitis (II): epidemiology of acute bronchiolitis. Review of the scientific evidence]

A review of the evidence on epidemiology, risk factors, etiology and clinical-etiological profile of acute bronchiolitis is presented. The frequency estimates are very heterogeneous; in the population under two years the frequency of admission for bronchiolitis is between 1 and 3.5%, primary care consultations between 4 and 20% and emergency visits between 1 and 2%. The frequency of admissions for respiratory infection by respiratory syncytial virus in the risk population is: in premature infants < or =32 weeks of gestation between 4.4 and 18%, in patients with bronchopulmonary dysplasia between 7.3 and 42%, and in infants with congenital heart disease between 1.6 and 9.8%. The main risk factors are: prematurity, chronic lung disease or bronchopulmonary dysplasia, congenital heart disease and age less than 3-6 months at onset of the epidemic. Other factors are: older siblings or day care attendance, male gender, exposure to smoking, breastfeeding for less than 1-2 months and variables associated with lower socioeconomic status. Respiratory syncytial virus is the dominant etiological agent, constituting just over half the cases (median 56%; interval 27% to 73%). Other viruses implicated, in descending order of frequency, are rhinovirus, adenovirus, metapneumovirus, influenza viruses, parainfluenza, enterovirus and bocavirus. In studies with genomic detection techniques, between 20 and 25% of cases the virus involved is not identified and between 9% and 27% of cases have viral co-infection. Although respiratory syncytial virus bronchiolitis shows more wheezing and retractions, longer duration of respiratory symptoms and oxygen therapy and are associated with lower use of antibiotics. This pattern is associated with the younger age of the patients and does not help us to predict the etiology. In general, the etiological identification is not useful for the management of patients. However, in young infants (<3 months) with febrile bronchiolitis in the hospital environment, conservative management may help these patients and avoid diagnostic and therapeutic procedures.

Palivizumab for prophylaxis against respiratory syncytial virus infection in children with cystic fibrosis

BACKGROUND

Respiratory syncytial virus (RSV) infection causes acute lung infection in infants and young children worldwide, resulting in considerable morbidity and mortality. Children with cystic fibrosis (CF) are prone to recurrent lung inflammation, bacterial colonisation and subsequent chronic airway disease, putting them at risk for severe RSV infections requiring intensive care and respiratory support. No treatment currently exists, hence prevention is important. Palivizumab is effective in reducing RSV hospitalisation rates and is recommended for prophylaxis in high-risk children with other conditions. It is unclear if palivizumab can prevent RSV hospitalisations and intensive care unit admissions in children with CF.

OBJECTIVES

To determine the efficacy and safety of palivizumab (Synagis((R))) compared with placebo, no prophylaxis or other prophylaxis, in preventing hospitalisation and mortality from RSV infection in children with CF.

SEARCH STRATEGY

We searched the Cochrane CF and Genetic Disorders Group Trials Register and scanned references of the eligible study and related reviews.Last search: 20 January 2010.

SELECTION CRITERIA

Randomised and quasi-randomised studies.

DATA COLLECTION AND ANALYSIS

The authors independently extracted data and assessed risk of bias.

MAIN RESULTS

One study (186 infants up to two years old) comparing five monthly doses of palivizumab (N=92) to placebo (N=94) over one RSV season was identified and met our inclusion criteria. At six months follow-up, one participant in each group was hospitalised due to RSV; there were no deaths in either group. In the palivizumab and placebo groups, 86 and 90 children experienced any adverse event, while 5 and 4 children had related adverse events respectively. Nineteeen children receiving palivizumab and 16 receiving placebo suffered serious adverse events; one participant receiving palivizumab discontinued due to this. At 12 months follow-up, there were no significant differences between groups in number of Pseudomonas bacterial colonisations or change in weight-to-height ratio.

AUTHORS' CONCLUSIONS

We identified one randomised controlled trial comparing five monthly doses of palivizumab to placebo in infants up to two years old with CF. While the overall incidence of adverse events was similar in both groups, it is not possible to draw conclusions on the safety and tolerability of RSV prophylaxis with palivizumab in infants with CF because the trial did not specify how adverse events were classified. Six months after treatment, the authors reported no clinically meaningful differences in outcomes; however no data were provided. Additional randomised studies are needed to establish the safety and efficacy of palivizumab in children with CF.

Seasonality of respiratory viral identification varies with age and Aboriginality in metropolitan Western Australia

BACKGROUND

Viral respiratory infections are a major cause of pediatric illness. It is not known whether seasonality of viruses differs between Aboriginal and non-Aboriginal children of varying ages.

METHODS

We extracted data on respiratory syncytial virus (RSV), influenza viruses A and B, parainfluenza virus types 1, 2, and 3 and adenovirus identified through cell culture or direct immunofluorescence between 1997 and 2005 from nasopharyngeal or throat specimens at Western Australia's only pediatric hospital. We used harmonic analysis in generalized linear models to examine the variations in seasonality of these viruses with Aboriginality and age.

RESULTS

A respiratory virus was identified in 32% of 32 741 specimens. RSV (18.6%), influenza virus A (5.1%), and parainfluenza virus 3 (4.0%) were most common. The median age at time of identification was lower in Aboriginal children than non-Aboriginal for all viruses except RSV. Seasonality differed between all viruses and varied with age for RSV, influenza viruses and adenovirus. Influenza viruses A and B activity peaked earlier in Aboriginal than non-Aboriginal children during 1997, 1998, and 2002.

CONCLUSIONS

All viruses showed distinct seasonality. Variability with age and different seasonal patterns for influenza viruses in Aboriginal children compared with non-Aboriginal children has to be taken into account when identifying target groups and timing for vaccination and other interventions.

[Success and failure predictors of non-invasive ventilation in acute bronchiolitis]

INTRODUCTION

The objective was to identify predictive factors for non-invasive ventilation (NIV) failure and to describe its use in bronchiolitis.

PATIENTS AND METHODS

Prospective observational study that included patients diagnosed with bronchiolitis with a modified Wood's Clinical Asthma Score 5, or oxygen saturation <92%, or venous CO(2) partial pressure (PCO(2)) 60 mm Hg, with no response to medical treatment, who received NIV from December 2005 to May 2008. We collected clinical data before NIV began and at 1, 6, 12, 24 and 48 h. Need for intubation was considered as NIV failure.

RESULTS

NIV was successful in 83% of 47 cases included. Patients in whom NIV failed had lower weight (5.2+/-2.2 vs. 3.5+/-0.8 kg, P=.011), lower age [1.8 (0.3-12.3) vs. 0.8 (0.4-4.3) months, P=.038)], lower heart rate (HR) before NIV began (176.3+/-19.1 vs. 160.4+/-9.7 beats/minute, P=.010), lower HR decrease at hours 1 (-16.0+/-17.3 vs.+1.1+/-11.6, P=.005) and 12 (-31.5+/-19.7 vs. -0.75+/-12.2, P=.002), presence of apnoeas (23.1% vs. 75%; P=.004) and of a predisposing condition (84.6% vs. 50%; P=.029). Multivariate analysis identified the absence of a predisposing condition, and a greater HR decrease during the first hour as success-associated independent factors (OR 0.004; 95% CI 0.000-0.664 and OR 0.896; 95% CI: 0.809-0.993, respectively).

CONCLUSIONS

NIV has a high success rate in bronchiolitis. The main parameters which can predict NIV success are the absence of a predisposing condition and a higher HR decrease in the first hour.

Epidemiologic, experimental, and clinical links between respiratory syncytial virus infection and asthma

Virtually all children experience respiratory syncytial virus (RSV) infection at least once during the first 2 years of life, but only a few develop bronchiolitis and more severe disease requiring hospitalization, usually in the first 6 months of life. Children who recover from RSV-induced bronchiolitis are at increased risk for the development of recurrent wheeze and asthma in later childhood. Recent studies suggest that there is an association between RSV-induced bronchiolitis and asthma within the first decade of life but that this association is not significant after age 13. Despite the considerable progress made in our understanding of several aspects of respiratory viral infections, further work needs to be done to clarify the molecular mechanisms of early interactions between virus and host cell and the role of host gene products in the infection process. This review provides a critical appraisal of the literature in epidemiology and experimental research which links RSV infection to asthma. Studies to date demonstrate that there is a significant association between RSV infection and childhood asthma and that preventing severe primary RSV infections can decrease the risk of childhood asthma.

Hospitalization rates for human metapneumovirus infection among 0- to 3-year-olds in Gipuzkoa (Basque Country), Spain

Numerous studies have been published on human metapneumovirus (HMPV) infection, but few have been population based. The main aim of this study was to estimate the incidence rate of hospitalization for community-acquired HMPV infection in infants and children aged <3 years. Between July 2004 and June 2007, 796 episodes (742 patients) of community-acquired acute respiratory infection were hospitalized. HMPV was detected in 90 episodes (11·3%). Fifty-nine episodes occurred in infants aged <1 year. The mean length of hospital stay was 6·2 days (range 2–31 days). Thirteen children required admission to the intensive care unit. Viral co-infections were detected in 46 episodes (51·1%). The incidence rate of hospitalization per 1000 inhabitants was 2·6 (95% CI 2·1–3·2), lower than that for respiratory syncytial virus, but higher than that observed for the influenza and parainfluenza viruses. HMPV is a major respiratory pathogen that leads to a high hospitalization rate.

[Severe bronchiolitis. Epidemiology and clinical course of 284 patients]

INTRODUCTION

Bronchiolitis is the leading cause of hospital admission and a frequent cause of pediatric intensive care unit (PICU) admission among infants during the winter months. The objective of this study was to analyze the characteristics and clinical course of patients admitted to the PICU for bronchiolitis.

PATIENTS AND METHOD

We performed a descriptive, observational study by clinical chart review of all patients admitted to the PICU for severe bronchiolitis from November 1994 to March 2006.

RESULTS

A total of 284 patients were included. Most were admitted during December and January and 74% had respiratory syncytial virus (RSV) infection. At least one risk factor for severe disease was present in 68% of the patients: the most frequent risk factor was age < 6 weeks (45%), followed by prematurity (30%). Mechanical ventilation was required in 64 of the 284 patients (24%). Mortality was 1.8% and was associated with chronic pre-existing illness (p < 0.001). The factors associated with a greater risk of mechanical ventilation and a longer PICU stay were the association of two or more risk factors (42/284; 15%), the presence of apnea (73/284; 25.7%), and images of pulmonary consolidation or atelectasis on admission chest X-ray (157/284; 55%).

CONCLUSIONS

Most patients admitted for severe bronchiolitis to the PICU are healthy infants whose principal risk factor is young age. The main predictors of severe clinical course during PICU stay are the association of two or more risk factors, the presence of apnea, and pulmonary consolidation on admission chest X-ray. Bronchiolitis-associated mortality is low and is associated with pre-existing chronic illness.

The association between respiratory syncytial virus infection and the development of childhood asthma: a systematic review of the literature

BACKGROUND

The relation between early respiratory syncytial virus (RSV) infection and later emergence of episodes of wheezing/asthma remains a subject of debate. We carried out a systematic review of studies of the association between RSV infection in the first 36 months of life and the subsequent development of asthma/bronchial hyperreactivity.

METHODS

A literature search for original studies on RSV respiratory infection published in English or Spanish over the last 21 years was conducted in the bibliographic databases Medline, Embase, and Indice Médico Español, and in the Cochrane library. Articles were included if they described original studies of confirmed RSV infection in children under 3 years of age, and had defined outcome variables. The methodologic quality of articles included in the review was evaluated according to the Hadorn criteria.

RESULTS

The review included 12 original articles that respond to the research question. The studies evaluated showed that RSV lower respiratory tract infection is associated with an increased risk for subsequent development of asthma/recurrent wheezing, and that this association becomes progressively smaller with increasing age.

CONCLUSION

On the basis of this systematic review of the literature, it can be concluded that a significant association exists between RSV infection in childhood and the long-term development of subsequent episodes of recurrent wheezing or asthma. However, the methodologic quality of the articles evaluated is limited, and hence additional studies are needed, ideally, with specific therapeutic interventions aimed at reducing RSV replication.

Incidencia y costes de la hospitalización por bronquiolitis y de las infecciones por virus respiratorio sincitial en la Comunidad Valenciana. Años 2001 y 2002

OBJECTIVE

To assess the incidence and costs of hospitalizations for bronchiolitis and respiratory syncytial virus (RSV) infections the Autonomous Community of Valencia, Spain.

METHODS

The minimum data set (MDS) of the Autonomous Community of Valencia was analyzed. Hospital discharges with the codes for bronchiolitis (with or without etiologic determination) and RSV infections occurring in 2001 and 2002 in children less than 2 years old were included. Second cases of bronchiolitis and RSV infections of possible nosocomial origin occurring during prolonged hospitalization were excluded. The average cost of hospitalization in a pediatric ward was estimated at euro 310.30 per day. To calculate the incidence, we assumed that 95 % of the hospitals reported to the MDS; the population used was that of the National Census, 2001.

RESULTS

A total of 3,705 hospitalizations were obtained, of which 3,507 were coded as bronchiolitis and 42.2 % of these were RSV-positive. Virological assessment varied greatly among hospitals. Hospitalizations were most frequent between October and April, with no differences between the two years. The incidence of bronchiolitis hospitalization was 40.2 cases/1000 children < 1 year/year, with an average annual cost of 3,618 thousand Euros.

CONCLUSIONS

The cost of bronchiolitis hospitalizations is high. Microbiological investigation is low in some hospitals, leading the economic impact of RSV on society to be underestimated.

Risk factors for hospitalization due to respiratory syncytial virus infection among infants in the Basque Country, Spain

This study analysed the role of several risk factors for hospitalization due to community-acquired, respiratory syncytial virus (RSV) infection. The risk factors detected in infants hospitalized for RSV infection in the first 24 months of life were compared with those in the general infant population in our region. There were 361 episodes of hospitalization in 357 infants. Eighty per cent of the infants did not present underlying conditions for severe RSV infection and only 10 (3%) were candidates for palivizumab prophylaxis. In multivariate analysis, birthweight of <2500 g was independently associated with hospitalization for RSV infection and was the most commonly detected medical risk factor. Other risk factors were maternal age at delivery <25 years, birth in the second half of the year, prematurity, suburban residence and congenital heart disease. In conclusion, together with well-known risk factors, we found that low birthweight was an independent factor for severe RSV infection.

[Recommendations for the prevention of respiratory syncytial virus infection]

Premature babies < or = 35 weeks gestation, with or without chronic lung disease (CLD), and infants affected by severe congenital heart disease should be considered high risk population for RSV infection and hospitalization. Hygienic measures and RSV monoclonal antibodies (palivizumab) have been found useful in decreasing rates of RSV hospitalization in these patients. Guidelines for their administration include: a) strongly recommended use in premature babies < or = 28 weeks gestation, or born between 29-32 weeks gestation and less than 6 months at start of RSV station or discharged along it, or affected by CLD in treatment during last 6 months or by severe congenital heart disease. Last two groups could be prophylaxed for two RSV seasons. b) Recommended use among premature babies between 32-35 weeks gestation and less than 6 months of age and presenting two or more risk factors: chronologic age < 10 weeks at start of RSV station, breastfeeding < or = 2 months (physician prescription), sibling < 14 years old, day-care assistance, family history of wheezing, > or = 4 adults at home, airways malformation or neuromuscular disease.

Influenza-related hospitalisations among children aged less than 5 years old in the Basque Country, Spain: a 3-year study (July 2001–June 2004)

This population-based study evaluated the incidence of virologically confirmed influenza-related hospitalisation in children aged <5 years between July 2001 and June 2004 in a region of southern Europe. Forty-nine children with influenza virus infection were hospitalised. The annual hospitalisation rates per 1000 inhabitants for each period were 5.1, 0 and 7.3 for infants aged less than 6 months, 0.9, 0.2 and 0.9 for children aged 6-23 months, and 0.7, 0.1 and 0.8 for those aged 24-59 months. Most of the children were hospitalised in the epidemic waves caused by the influenza A/H3N2 virus and were previously healthy. This study supports the need to introduce measures to reduce the burden of disease due to influenza virus infection in young children. New vaccines or vaccination strategies that could be applied in infants should be developed.

The immune response to human metapneumovirus is associated with aberrant immunity and impaired virus clearance in BALB/c mice

Human metapneumovirus (HMPV), recently identified in isolates from children hospitalized with acute respiratory tract illness, is associated with clinical diagnosis of pneumonia, asthma exacerbation, and acute bronchiolitis in young children. HMPV has been shown to cocirculate with respiratory syncytial virus (RSV) and mediate clinical disease features similarly to RSV. Little is known regarding the pathophysiology or immune response associated with HMPV infection; thus, animal models are needed to better understand the mechanisms of immunity and disease pathogenesis associated with infection. In this study, we examine features of the innate and adaptive immune response to HMPV infection in a BALB/c mouse model. Primary HMPV infection elicits weak innate and aberrant adaptive immune responses characterized by induction of a Th2-type cytokine response at later stages of infection that coincides with increased interleukin-10 expression and persistent virus replication in the lung. Examination of the cytotoxic T lymphocyte and antibody response to HMPV infection revealed a delayed response, but passive transfer of HMPV-specific antibodies provided considerable protection. These features are consistent with virus persistence and indicate that the immune response to HMPV is unique compared to the immune response to RSV.

[Chest radiograph in bronchiolitis: is it always necessary?]

BACKGROUND

The routine use of chest radiograph in infants with bronchiolitis increases health costs and can often unnecessarily expose the patient to radiation.

OBJECTIVES

To evaluate the prevalence of infiltrate/atelectasis in infants younger than 2 years who presented to the emergency department with bronchiolitis, to assess whether patient management is changed after viewing the chest radiograph and to determine which clinical variables can accurately identify children with normal radiographs, with a view to reducing unnecessary radiological investigations.

PATIENTS AND METHODS

From October 2003 to December 2004, infants aged < 24 months evaluated in the emergency department of the Severo Ochoa Hospital (Madrid) with a diagnosis of bronchiolitis were included in this study. The variables registered were age, sex, time since onset, respiratory rate, temperature, asymmetry on auscultation, oxygen saturation and the virus identified. A chest radiograph was obtained and the need for admission was evaluated before and after obtaining the results.

RESULTS

Two hundred fifty-two infants were included, of which 50 % were aged less than 5 months. Infiltrate/atelectasis was identified in 14.3 % (95 % CI: 10.1-18.5; kappa coefficient: 0.64). Patients with infiltrate/atelectasis were 2.5 times more likely to have a temperature of > or = 38 degrees C (p: 0.004), O2 saturation of < 94 % (p: 0,006) and to be admitted before the results of chest radiograph were known. No differences were found between children with and without infiltrate in age at presentation, sex, disease duration, respiratory rate or identified virus. Patient management was modified in 30 % of patients with infiltrate/ atelectasis. Patients with a temperature of < 38 degrees and O2 saturation of > 94 % had a 92 % probability of normal chest radiograph.

CONCLUSIONS

Most infants presenting with bronchiolitis had a normal chest radiograph. Temperature >or = 38 degrees and O2 saturation < 94 % were significantly associated with infiltrate/atelectasis. In most infants with bronchiolitis, the absence of fever and hypoxia are good predictors of normal chest radiographs.

[Asthma and respiratory syncytial virus. New opportunities for therapeutic intervention]

Numerous studies have described an association between respiratory sincticial virus (RSV) infection in infancy and the subsequent development of airway hyperresponsiveness (AHR). Besides the exaggerated immune response and the abnormal neurogenic mechanisms induced by RSV, recent studies have correlated the "persistence" of RSV in the lower respiratory tract with the development of AHR. Several investigators have evaluated whether treatment with antiviral or immunosuppressive agents could decrease the long term respiratory abnormalities induced by RSV. The RSV murine model has allowed us to study the immunopathogenesis of RSV-induced AHR. Once the airway obstruction, typical of acute disease, is resolved and no virus is longer detected by cell cultures, mice progress into a chronic phase characterized by AHR and persistent airway inflammation. The use of polymerase chain reaction assay for RSV quantitation has demonstrated, quite unexpectedly, the presence of RSV RNA in the lower respiratory tract of mice during the chronic phase of the disease. As an example of intervention, the administration of an anti-RSV neutralizing antibody (palivizumab) was associated with a significant reduction in viral replication, pulmonary inflammation and inflammatory cytokines, as well as a significant improvement in the pulmonary function both in the acute and chronic phases of the disease. Future clinical studies to determine whether therapy with palivizumab can prevent the long-term morbidity associated with RSV in children are warranted.