Respiratory Syncytial Virus Infection in High-risk Infants - an Update on Palivizumab Prophylaxis

Efficacy and Safety of Palivizumab as a Prophylaxis for Respiratory Syncytial Virus (RSV) Disease: An Updated Systemic Review and Meta-Analysis

This systematic review and meta-analysis aimed to summarize the current evidence regarding the efficacy and safety of palivizumab as a prophylaxis for respiratory syncytial virus (RSV) disease. We searched MEDLINE via PubMed, Scopus, Cochrane, Web of Science, Embase, and Science Direct from inception till November 2023. Studies that assessed the efficacy and safety of palivizumab in infants aged between 28 days and three months of age were included. We analyzed the data using Review Manager 5.4 software, with results pooled across studies and expressed as risk ratios (RR) with 95% confidence intervals (CI). A total of 10 studies were included. The effect estimates favored palivizumab over placebo regarding the hospitalization for RSV infection (RR=0.51, 95% CI: 0.40 to 0.65; P<0.00001) and ICU admission (RR=0.49, 95% CI: 0.30 to 0.81; P=0.005). On the other hand, the effect estimate showed no significant difference between palivizumab and placebo regarding all-cause mortality (RR=0.69, 95% CI: 0.42 to 1.15; P=0.16), lower respiratory tract infection (RR=0.42, 95% CI: 0.11 to 1.69; P=0.22), and need for mechanical ventilation (RR=0.75, 95% CI: 0.34 to 1.67; P=0.48). Palivizumab can be considered a prophylaxis for RSV disease in young children as it is safe, well-tolerated, and effective in reducing RSV hospitalizations. However, further research through high-quality randomized controlled trials is required to determine its efficacy as a therapeutic agent for established RSV infections.

Impact of COVID-19 Pandemic on Respiratory Syncytial Virus (RSV) Prophylaxis Program: A Tertiary-Care Center Experience

OBJECTIVES

The purpose of this investigation was to evaluate the effects of the COVID-19 pandemic on the respiratory syncytial virus (RSV) prevention program at our institution across three time frames: 2019-2020, 2020-2021, and 2021-2022.

METHODS

We carried out a descriptive, single-site observational study spanning four years, from June 2019 to June 2022. Our study included patients in our institution's RSV program who met our enrollment criteria. We collected information about the number of children receiving immunoprophylaxis, immunoprophylaxis doses, and RSV risk factors.

RESULTS

The number of patients receiving immunoprophylaxis dropped across the three periods, from 315 patients in the first period (2019-2020) to 176 in the second period (2020-2021), and further decreased to 128 in the third period (2021-2022). Following the COVID-19 pandemic, there was a 50% reduction in the number of patients receiving immunoprophylaxis. The proportion of RSV-infected patients remained relatively similar in the first and second periods (2.86% and 2.27%, respectively) but increased in the third period (5.47%). In the first period, most patients (60.32%) received seven doses, 11.75% got four to six doses, and 27.95% received three doses or fewer. The second period saw 59.66% of patients receiving four to six doses and 40.34% receiving three doses or fewer. In the third period, a mere 9.38% received four to five doses, while 90.63% got three doses or fewer.

CONCLUSIONS

While preventative measures associated with COVID-19 may have helped reduce the number of RSV cases, the pandemic seems to have caused a significant decrease in the number of children receiving immunoprophylaxis and the doses of immunoprophylaxis. More extensive, multicenter research is needed to understand the impact of the COVID-19 pandemic on RSV immunoprophylaxis, its activity, and seasonal patterns fully.

New Developments and Challenges in Antibody-Based Therapies for the Respiratory Syncytial Virus

Since the discovery of the human respiratory syncytial virus (hRSV), multiple research efforts have been conducted to develop vaccines and treatments capable of reducing the risk of severe disease, hospitalization, long-term sequelae, and death from this pathogen in susceptible populations. In this sense, therapies specifically directed against hRSV are mainly based on monoclonal and polyclonal antibodies such as intravenous IgG (IVIG)-RSV and the monoclonal antibody palivizumab. However, these therapies are associated with significant limitations, including the need for the recruitment of a high number of convalescent volunteers who donate blood to procure IVIG-RSV and the costs associated with the need for repeated administrations of palivizumab. These limitations render this product not cost-effective for populations other than high-risk patients. These problems have underscored that it is still necessary to identify new safe and effective therapies for human use. However, these new therapies must benefit from a comparatively cheap production cost and the opportunity to be available to the high-risk population and anyone who requires treatment. Here, we review the different antibodies used to prevent the pathology caused by hRSV infection, highlighting therapies currently approved for human use and their clinical value. Also, the new, most promising candidates based on preclinical studies and clinical trial results are revised.

Viral burden and diversity in acute respiratory tract infections in hospitalized children in wet and dry zones of Sri Lanka

The present study was done to identify the viral diversity, seasonality and burden associated with childhood acute respiratory tract infection (ARTI) in Sri Lanka. Nasopharyngeal aspirates (NPA) of hospitalized children (1 month-5 years) with ARTI were collected in 2 centers (wet and dry zones) from March 2013 to August 2014. Respiratory viral antigen detection by immunofluorescence assay (IFA) was used to identify the infecting viruses. IFA negative 100 NPA samples were tested for human metapeumovirus (hMPV), human bocavirus and corona viruses by polymerase chain reaction. Of the 443 and 418 NPAs, 37.2% and 39.4% were positive for any of the 8 different respiratory viruses tested from two centers studied. Viral co-infection was detected with respiratory syncytial virus (RSV) in both centers. Peak viral detection was noted in the wet zone from May-July 2013 and 2014 and in the dry zone from December-January 2014 suggesting a local seasonality for viral ARTI. RSV showed a clear seasonality with a direct correlation of monthly RSV infections with rainy days in the wet zone and an inverse correlation with temperature in both centers. The case fatality rate was 2.7% for RSV associated ARTI. The overall disability adjusted life years was 335.9 and for RSV associated ARTI it was 241.8. RSV was the commonly detected respiratory virus with an annual seasonality and distribution in rainy seasons in the dry and wet zones of Sri Lanka. Identifying the virus and seasonality will contribute to employ preventive measures and reduce the empirical use of antibiotics in resource limited settings.

A Multivariate Age-Structured Stochastic Model with Immunization Strategies to Describe Bronchiolitis Dynamics

Bronchiolitis has a high morbidity in children under 2 years old. Respiratory syncytial virus (RSV) is the most common pathogen causing the disease. At present, there is only a costly humanized monoclonal RSV-specific antibody to prevent RSV. However, different immunization strategies are being developed. Hence, evaluation and comparison of their impact is important for policymakers. The analysis of the disease with a Bayesian stochastic compartmental model provided an improved and more natural description of its dynamics. However, the consideration of different age groups is still needed, since disease transmission greatly varies with age. In this work, we propose a multivariate age-structured stochastic model to understand bronchiolitis dynamics in children younger than 2 years of age considering high-quality data from the Valencia health system integrated database. Our modeling approach combines ideas from compartmental models and Bayesian hierarchical Poisson models in a novel way. Finally, we develop an extension of the model that simulates the effect of potential newborn immunization scenarios on the burden of disease. We provide an app tool that estimates the expected reduction in bronchiolitis episodes for a range of different values of uptake and effectiveness.

The respiratory syncytial virus (RSV) prefusion F-protein functional antibody repertoire in adult healthy donors

Respiratory syncytial virus (RSV) is the leading cause of death from lower respiratory tract infection in infants and children, and is responsible for considerable morbidity and mortality in older adults. Vaccines for pregnant women and elderly which are in phase III clinical studies target people with pre-existing natural immunity against RSV. To investigate the background immunity which will be impacted by vaccination, we single cell-sorted human memory B cells and dissected functional and genetic features of neutralizing antibodies (nAbs) induced by natural infection. Most nAbs recognized both the prefusion and postfusion conformations of the RSV F-protein (cross-binders) while a smaller fraction bound exclusively to the prefusion conformation. Cross-binder nAbs used a wide array of gene rearrangements, while preF-binder nAbs derived mostly from the expansion of B-cell clonotypes from the IGHV1 germline. This latter class of nAbs recognizes an epitope located between Site Ø, Site II, and Site V on the F-protein, identifying an important site of pathogen vulnerability.

Assessment of the Effects of Active Immunisation against Respiratory Syncytial Virus (RSV) using Decision-Analytic Models: A Systematic Review with a Focus on Vaccination Strategies, Modelling Methods and Input Data

BACKGROUND

Several vaccine and antibody candidates are currently in development for the prevention of lower respiratory tract infections caused by the respiratory syncytial virus (RSV).

METHODS

We searched MEDLINE, Embase, and SCOPUS and included model-based evaluations of RSV vaccinations. Two reviewers performed the selection, data extraction, and quality evaluation with EVIDEM. Cost-effectiveness (CE) estimates were converted to $US purchasing power parity (PPP), year 2018 values. Potential economic and epidemiological outcomes were summarised for maternal, infant, children, and elderly vaccinations. The PROSPERO identifier is CRD42019122570.

RESULTS

In total, 22 model-based studies were reviewed. On average, a potential 27% reduction in RSV hospitalisations in infants was projected for maternal vaccination and 50% for direct infant immunisation. The CE of maternal vaccination was $US1766-5857 PPP 2018/disability-adjusted life-years (DALYs) for Global Alliance for Vaccines and Immunisation (Gavi)-eligible countries. For England, the maximum cost-effective price of maternal vaccination was estimated at $US81.5 PPP 2018. Infant vaccination was associated with higher CE ratios in low- and high-income settings. Vaccination of neonates born before the RSV season was the most cost effective in high-income settings. Higher values for vaccine effectiveness, duration of protection, and vaccine uptake increased the benefits. Due to indirect effects, the vaccination of school-age children and a cocooning strategy were effective alternatives to protect infants, and the vaccination of children aged < 5 years had a beneficial impact on the elderly.

CONCLUSION

RSV vaccines with anticipated characteristics may reduce a sizeable proportion of the RSV burden. The results are subject to uncertainty because of the limited epidemiological and clinical data. Data on RSV incidence and hospitalisation risk for granular age strata should be prioritised to facilitate the evaluation of RSV interventions and decision making.

Reappraisal of the Subtropical Guidelines on Palivizumab Prophylaxis in Congenital Heart Disease

Objective: To define the impact of associated abnormalities on the efficacy of the novel subtropical guidelines for palivizumab prophylaxis on respiratory syncytial virus (RSV)-related hospitalizations in patients with hemodynamically significant congenital heart disease (hsCHD). Method: This prospective study enrolled every patient seen at a tertiary care center for hsCHD, who was born between 2014 and 2018 and received at least 1 dose of palivizumab, according to the subtropical guidelines. The patients were followed until the age of 2 years. Results: A total of 772 patients (49% male) were enrolled. Cyanotic CHD was seen in 46% of patients, of whom 23% had associated abnormalities. Lung/airway abnormalities (14%) were the most common followed by the genetic syndromes associated with CHD (7.3%). Among the 772 patients, RSV-related hospitalizations occurred in 3.2 and 2.2% children aged ≤ 12 and 13-24 months, respectively. Most of the RSV infections occurred in patients no longer satisfying the criteria for palivizumab prophylaxis. The patients with associated abnormalities but not the type of CHD, patient age, and patient sex were risk factors for RSV-related hospitalizations. The rates of RSV-related hospitalizations, admission to the intensive care unit, and endotracheal intubation were higher for patients with associated anomalies than for other patients before 24 months of age (10.2 vs. 4.0%, 67 vs. 33%, and 39 vs. 4.2%, p = 0.004, 0.06, 0.013, respectively). Conclusion: Children with abnormalities, especially genetic syndromes and lung/airway problems associated with CHD, are at high risk for RSV-related hospitalization. Our current subtropical guidelines for palivizumab prophylaxis in patients with hsCHD, should be revised to include the results of this study.

Cost-effectiveness of palivizumab in infants with congenital heart disease: a Swedish perspective

Background

Infants with congenital heart disease (CHD) have an increased risk of morbidity and mortality during a respiratory syncytial virus (RSV) infection. The aim of this study was to estimate the cost-effectiveness of palivizumab as RSV-prophylaxis among infants with CHD, including the effect of delayed heart surgery and asthma.

Methods

A simulation model with data from the literature and health care authorities including costs and utilities was developed to estimate costs and health effects over a lifetime for a cohort of CHD infants receiving palivizumab compared to no RSV-prophylaxis.

Results

The prophylaxis treatment incurred a cost of 3664 EUR per treated infant. However, due to cost-savings from primarily avoiding hospitalizations (5145 EUR/treated infant) and avoiding heart complications due to delayed heart surgery (2082 EUR/treated infant), the RSV-prophylaxis treatment resulted in a total cost-saving of 3833 EUR per treated infant. At the same time, the prophylaxis-treated cohort accumulated more life-years and higher quality of life than the non-prophylaxis cohort.

Conclusion

This study confirms that RSV-prophylaxis in severe CHD infants less than one year of age is cost beneficial. Avoiding delayed heart surgeries is an important benefit of prophylaxis and should be taken into consideration.

Delivery of ALX-0171 by inhalation greatly reduces respiratory syncytial virus disease in newborn lambs

Respiratory syncytial virus (RSV) is a common cause of acute lower respiratory disease in infants and young children worldwide. Currently, treatment is supportive and no vaccines are available. The use of newborn lambs to model hRSV infection in human infants may provide a valuable tool to assess safety and efficacy of new antiviral drugs and vaccines. ALX-0171 is a trivalent Nanobody targeting the hRSV fusion (F) protein and its therapeutic potential was evaluated in newborn lambs infected with a human strain of RSV followed by daily ALX-0171 nebulization for 3 or 5 consecutive days.

Colostrum-deprived newborn lambs were infected with hRSV-M37 before being treated by daily nebulization with either ALX-0171 or placebo. Two different treatment regimens were examined: day 1–5 or day 3–5 post-infection. Lambs were monitored daily for general well-being and clinical parameters. Respiratory tissues and bronchoalveolar lavage fluid were collected at day 6 post-inoculation for the quantification of viral lesions, lung viral titers, viral antigen and lung histopathology.

Administration by inhalation of ALX-0171 was well-tolerated in these hRSV-infected newborn lambs. Robust antiviral effects and positive effects on hRSV-induced lung lesions and reduction in symptoms of illness were noted. These effects were still apparent when treatment start was delayed and coincided with peak viral loads (day 3 post-infection) and at a time point when signs of RSV disease were apparent. The latter design is expected to have high translational value for planned clinical trials. These results are indicative of the therapeutic potential of ALX-0171 in infants.

Hospitalization for Respiratory Syncytial Virus in Children with Down Syndrome Less than 2 Years of Age: A Systematic Review and Meta-Analysis

OBJECTIVES

To compare the respiratory syncytial virus (RSV)-related hospitalization rate, hospital length of stay (LOS), and need for assisted ventilation in children aged <2 years with Down syndrome and those without Down syndrome.

STUDY DESIGN

MEDLINE, Embase, and CINAHL databases were searched from inception up to December 2017. Studies that provided data on RSV-related hospitalization in children aged <2 years with Down syndrome and those without Down syndrome were included. Data were independently extracted in pairs by 2 reviewers and synthesized with random-effects meta-analysis.

RESULTS

In 10 studies including a total of 1 748 209 children, 12.6% of the children with Down syndrome (491 of 3882) were hospitalized with RSV infection. The presence of Down syndrome was associated with a significantly higher risk of RSV-related hospitalization (relative risk [RR], 6.06; 95% CI, 4.93-7.45; I² = 65%; Grading of Recommendations, Assessment, Development and Evaluation [GRADE], moderate). RSV-related LOS (mean difference, 2.11 days; 95% CI, 1.47-2.75 days; I² = 0%; GRADE, low), and the need for assisted ventilation (RR, 5.82; 95% CI, 1.81-18.69; I² = 84%; GRADE, low). Children with Down syndrome without congenital heart disease (RR, 6.31; 95% CI, 4.83-8.23; GRADE, moderate) also had a significantly higher risk of RSV-related hospitalization. The risk of RSV-related hospitalization remained significant in the subgroup of children aged <1 year (RR, 6.25; 95% CI, 4.71-8.28; GRADE, high).

CONCLUSION

RSV-related hospitalization, hospital LOS, and the need for assisted ventilation are significantly higher in children with Down syndrome aged <2 years compared with those without Down syndrome. The results should prompt reconsideration of the need for routine RSV prophylaxis in children with Down syndrome up to 2 years of age.

Overview of prevention and management of acute bronchiolitis due to respiratory syncytial virus

INTRODUCTION

Respiratory Syncytial Virus (RSV) is the most common cause of Acute Bronchiolitis (AVB) in infants. AVB causes significant morbidity and mortality worldwide, most deaths occurring in the developing world. AVB causes respiratory distress in infants, leading to respiratory failure in some cases. Disease is more severe in infants with risk factors, such as prematurity, chronic cardiac and lung disease and immunodeficiency. Areas covered: Despite major advances in supportive care in the developed world, which has led to a significant reduction in mortality, treatment remains symptomatic and supportive. No specific antiviral treatment has yet proven to be effective. Prevention of disease with monoclonal antibodies has proven to reduce illness severity in those with risk factors, however, this is prohibitively expensive, particularly for the developing world. Prospects for vaccine development are improving. However, because most disease is in young infants, maternal immunization is necessary. However, due to the transient nature of RSV immunity and the circulation of multiple subtypes, vaccines proven to be effective in adult challenge models have yet to be translated to protection in infants. Expert commentary: Despite advances in preventative treatments, adherence to evidence-based guidelines provides the best prospect for successful reduction in morbidity and mortality.

Superensemble forecast of respiratory syncytial virus outbreaks at national, regional, and state levels in the United States

Respiratory syncytial virus (RSV) infections peak during the winter months in the United States, yet the timing, intensity, and onset of these outbreaks vary each year. An RSV vaccine is on the cusp of being released; precise models and accurate forecasts of RSV epidemics may prove vital for planning where and when the vaccine should be deployed. Accurate forecasts with sufficient spatial and temporal resolution could also be used to support the prevention or treatment of RSV infections. Previously, we developed and validated an RSV forecast system at the regional scale in the United States. This model-inference system had considerable forecast skill, relative to the historical expectance, for outbreak peak intensity, total outbreak size, and onset, but only marginal skill for predicting the timing of the outbreak peak. Here, we use a superensemble approach to combine three forecasting methods for RSV prediction in the US at three different spatial resolutions: national, regional, and state. At the regional and state levels, we find a substantial improvement of forecast skill, relative to historical expectance, for peak intensity, timing, and onset outbreak up to two months in advance of the predicted outbreak peak. Moreover, due to the greater variability of RSV outbreaks at finer spatial scales, we find that improvement of forecast skill at the state level exceeds that at the regional and national levels. Such finer scale superensemble forecasts may be more relevant for effecting local-scale interventions, particularly in communities with a high burden of RSV infection.

Maternal immunization with a recombinant adenovirus-expressing fusion protein protects neonatal cotton rats from respiratory syncytia virus infection by transferring antibodies via breast milk and placenta

We evaluated the efficacy of a recombinant adenovirus that expresses a membrane-truncated respiratory syncytial virus (RSV) fusion protein (Ad-F0ΔTM) in newborns via maternal immunization (MI) of pregnant cotton rats. Intranasal Ad-F0ΔTM immunization was given to pregnant female rats, and MI-newborn rats were then challenged intranasally with RSV. Anti-RSV IgGs were observed in the serum of MI-newborn rats after birth. The pulmonary viral loads in Ad-F0ΔTM vs. control vector, Ad-LacZ, and MI-newborns on day 3 post-challenge were reduced by 4 log₁₀/g lung. The neutralizing antibody remained for up to 3 weeks in the serum of MI-newborns, which is when weaning began. Ad-F0ΔTM protected MI-newborns from RSV challenge for 1 week. Vertical-transferred protective antibodies were examined in the breast milk and placenta as well. Finally, anti-RSV immunity was not boosted but was only primed during the next RSV exposure in Ad-F0ΔTM-MI-newborns. Maternal Ad-F0ΔTM immunization provides acute protection against RSV infection in neonates.

Respiratory syncytial virus associated hospitalizations in children with congenital diaphragmatic hernia

BACKGROUND

To evaluate the risk of RSV infection in infants and children with congenital diaphragmatic hernia (CDH) over two consecutive RSV seasons.

METHODS

Retrospective, single-center cohort study from southern Austria including infants with CDH born between 1993 and 2012. Infants were retrieved by searching via ICD-10 codes Q79.0 and Q79.1 and by using a local electronic database. Children were followed over 2 years of life including at least two consecutive RSV seasons (November to April). We also defined a group of hypothetical RSV infections with the following criteria: 70% of the admissions due to a respiratory infection (diagnosis of bronchiolitis and/or LRI score ≥3) during the RSV seasons over the first 2 years of life, when no test for RSV was performed.

RESULTS

Twenty-nine of 45 infants with CDH comprised the study population (6 were lost to follow-up and 10 died) of whom 9 (31%) exhibited 17 hospitalizations due to respiratory illness. Two hospitalized infants (6.9% of the study population) tested RSV positive, one during the first and the other during the second RSV season. Nine of 29 infants (31%) had documentation of palivizumab prophylaxis, none (0%) had proven RSV hospitalization compared to 1 of 20 (5%) without prophylaxis during the first RSV season (p = 0.256). Including the hypothetical cases, we calculated 0 of 9 (0%) in the palivizumab group and 4 of 20 (20%) in the group without prophylaxis (p = 0.079).

CONCLUSIONS

We found a moderate rate of proven RSV hospitalizations in infants with CDH, and palivizumab prophylaxis led to a non-significant reduction of proven and hypothesized RSV hospitalizations.

Burden of Respiratory Syncytial Virus Hospitalizations in Canada

Objective

To examine the socioeconomic burden of respiratory syncytial virus (RSV) disease for Canadian infants hospitalized for the condition.

Data and Methods

The descriptive study used data collected in Alberta, Canada, during 2 consecutive RSV seasons. Infants (<1 year of age) were included if they had not received palivizumab and were hospitalized with a confirmed diagnosis of RSV. Hospitalization resource use and parental time burden, out-of-pocket costs, lost work productivity, and stress and anxiety were assessed.

Results

13.4% of all infants (n = 67) had intensive care unit (ICU) admission, and average ICU stay for these infants was 6.5 days. Families had average out-of-pocket expenses of 736.69 Canadian dollars (CAD $), and the average time both parents spent in hospital was nearly 7 days (164.0 hours). For working parents (n = 43), average absenteeism was 49% and overall work impairment was 77.8%. Parents also exhibited significant parental stress (3.6 on the Parental Stressor Scale: 43.9 state anxiety and 36.9 trait anxiety scores).

Conclusions

Results indicate a high burden associated with the hospitalization of an infant due to RSV disease in terms of resource use, time, productivity, costs, and stress, even among a population of infants not considered to be at risk for the condition.

Evaluation of the Financial and Health Burden of Infants at Risk for Respiratory Syncytial Virus

BACKGROUND

Respiratory syncytial virus (RSV) is the leading viral cause of death in infants younger than 1 year. In July 2014, the American Academy of Pediatrics (AAP) Committee on Infectious Diseases concluded that the "limited clinical benefit" for infants born at more than 29 weeks' gestation, together with the associated high cost of the immunoprophylaxis, no longer supported the routine use of palivizumab (Synagis).

PURPOSE

To evaluate the impact of the newly adopted AAP palivizumab prophylaxis administration on health and subsequent hospital costs of infants born between 29 and less than 32 weeks' gestation.

METHODS

A retrospective cohort analysis from a single institution across the duration of the study comparing the clinical and financial outcomes of infants (aged < 32 weeks) treated under the 2009 AAP guidelines (PRE) and infants (aged >29 weeks) managed after the 2014 AAP guidelines (POST) took effect.

RESULTS

RSV-positive admissions were greater in the POST cohort versus the PRE cohort (P = .04). There were no readmission deaths due to RSV infection in either cohort. The number needed to treat to avoid a single RSV-positive hospitalization was 20 infants at an estimated palivizumab cost of $90,000 to avoid an estimated hospital cost of $29,000.

IMPLICATIONS FOR PRACTICE

Assessment of individual risk factors and their ability to predict severe RSV risk/disease, thus, would allow providers greater flexibility in determining need for prophylaxis therapy.

IMPLICATIONS FOR RESEARCH

Longitudinal evaluation of financial and clinical outcomes is needed to determine the impact of the 2014 AAP revised regulatory guidelines.

Burden of paediatric respiratory syncytial virus disease and potential effect of different immunisation strategies: a modelling and cost-effectiveness analysis for England

BACKGROUND

Vaccines and prophylactic antibodies against respiratory syncytial virus (RSV) are in development and likely to be available in the next 5-10 years. The most efficient way to use these products when they become available is an important consideration for public health decision makers.

METHODS

We performed a multivariate regression analysis to estimate the burden of RSV in children younger than 5 years in England (UK), a representative high-income temperate country, and used these results to assess the potential effect of different RSV immunisation strategies (targeting vaccination for infants, or pregnant women, or prophylactic antibodies for neonates). We did a cost-effectiveness analysis for these strategies, implemented either separately or concurrently, and assessed the effect of restricting vaccination to certain months of the year.

FINDINGS

We estimated that RSV is responsible for 12 primary care consultations (95% CI 11·9-12·1) and 0·9 admissions to hospital annually per 100 children younger than 5 years (95% CI 0·89-0·90), with the major burden occurring in infants younger than 6 months. The most cost-effective strategy was to selectively immunise all children born before the start of the RSV season (maximum price of £220 [95% uncertainty interval (UI) 208-232] per vaccine, for an incremental cost-effectiveness ratio of £20 000 per quality-adjusted life-year). The maximum price per fully protected person that should be paid for the infant, newborn, and maternal strategies without seasonal restrictions was £192 (95% UI 168-219), £81 (76-86), and £54 (51-57), respectively.

INTERPRETATION

Nearly double the number of primary care consultations, and nearly five times the number of admissions to hospital occurred with RSV compared with influenza. RSV vaccine and antibody strategies are likely to be cost-effective if they can be priced below around £200 per fully protected person. A seasonal vaccination strategy is likely to provide the most direct benefits. Herd effects might render a year-round infant vaccination strategy more appealing, although it is currently unclear whether such a programme would induce herd effects.

FUNDING

UK National Institute for Health Research.

Product review on the monoclonal antibody palivizumab for prevention of respiratory syncytial virus infection

Respiratory syncytial virus (RSV) accounts for about 20% of all respiratory infections in children below the age of 5 y. It is associated with up to 63% of all acute respiratory infections and up to 81% of all viral lower respiratory tract infections causing hospitalization in infants and young children. RSV leads to seasonal epidemics between November and April in the northern hemisphere. Most severe infections (RSV accounts for 50 to 80% of all cause bronchiolitis) affect infants younger than 6 months of age and high-risk infants including those born preterm with or without bronchopulmonary dysplasia and those with hemodynamically significant congenital heart disease up to an age of 24 months. Palivizumab, a highly potent RSV-neutralizing monoclonal antibody (Mab), has been licensed in 1998 for prophylactic use to prevent RSV associated hospitalizations in high-risk infants. This Mab is given by monthly intramuscular injection at a dose of 15 mg/kg over the RSV season (up to 5 times). Palivizumab proved to be safe and well-tolerated in this population. Concerns have been raised regarding cost-effectiveness of palivizumab and thus, palivizumab prophylaxis is mainly limited to selected high-risk infants for the first RSV season. Long-lasting Mabs will be the next future approach in the prophylaxis of RSV hospitalization until a vaccine is developed.

Respiratory Syncytial Virus Infection-associated Hospitalization Rates in Infants and Children With Cystic Fibrosis

BACKGROUND

Infections with respiratory syncytial virus (RSV) are the leading cause for hospital admissions in infants and young children. The incidence of RSV-related hospitalizations in patients with cystic fibrosis (CF) is unclear. To date, no effective treatment for RSV infections is available. Thus, prophylaxis with the monoclonal antibody palivizumab is an important option.

METHODS

In a retrospective, single-center study at the Department of Pediatrics and Adolescent Medicine of the Medical University Graz, Austria, we analyzed all CF patients born between 1995 and 2012, who were admitted for respiratory problems between 1995 and 2014. We also defined a group of hypothetical RSV infections with the following criteria: admission caused by a respiratory infection during the first RSV season of life when no test for RSV was performed. Furthermore, we assessed the effectiveness of palivizumab as a prevention of RSV-related hospitalizations.

RESULTS

A total of 51 patients with CF were identified. The RSV-related hospitalization rate for the first RSV season was 0. Two patients (3.9%) were hospitalized 3 and 4 times, respectively, caused by RSV infections. The mean age at the time of admission was 12.4 ± 2.5 years. One case (1.9%) met our criteria for hypothetical RSV infections. There was no difference in RSV-related hospitalization rates between patients who received palivizumab and those who did not.

CONCLUSIONS

We found a low rate of RSV-related hospitalizations and could not demonstrate a benefit of palivizumab prophylaxis regarding a decrease of RSV-related hospital admissions. The role of RSV reinfections in CF patients beyond infancy appears to be underestimated.

Comparing First- and Second-year Palivizumab Prophylaxis in Patients With Hemodynamically Significant Congenital Heart Disease in the CARESS Database (2005-2015)

BACKGROUND

Respiratory syncytial virus hospitalization (RSVH) rates in children <2 years of age with hemodynamically significant congenital heart disease (HSCHD) are 2- to 4-fold higher compared with healthy term infants. Pediatric recommendations differ as to whether palivizumab is beneficial beyond 1 year of age. The objective of this study was to determine whether differences exist in respiratory-related illness hospitalization (RIH) and RSVH in HSCHD infants receiving palivizumab during the first year versus second year of life in the Canadian Registry of Palivizumab.

METHODS

The Canadian Registry of Palivizumab is a prospective database of infants who received ≥1 dose of palivizumab in 32 hospitals from 2005 to 2015. Demographic data were collected at enrollment and RIH events recorded monthly. Infants <24 months of age with HSCHD were recruited.

RESULTS

Of 1909 HSCHD infants, 1380 (72.3%) in the first year (mean age, 4.2 months) and 529 (27.7%) in the second year of life (mean age, 17.8 months) received prophylaxis. Baseline demographics for day-care attendance, multiple births, enrollment age and weight differed between the groups (all P < 0.05). Additionally, second year infants had a more complicated neonatal course, with significantly longer length of stay (51.2 vs. 24.9 days) compared with those in the first year. The RIH and RSVH rates in the first year were 11.2% and 2.3% and in the second year were 10.6% and 1.7%. Cox regression analysis showed similar hazard for RIH [hazard ratio, 1.9; 95% confidence interval: 0.7-4.6; P = 0.18] and RSVH [hazard ratio, 2.0; 95% confidence interval: 0.2-16.5; P = 0.52].

CONCLUSIONS

Infants in the first and second year of life had a similar RSVH hazard. These findings suggest that infants in the second year with HSCHD, who remain unstable, are equally at risk for RSVH and merit prophylaxis.

Immunological Features of Respiratory Syncytial Virus-Caused Pneumonia-Implications for Vaccine Design

The human respiratory syncytial virus (hRSV) is the causative agent for high rates of hospitalizations due to viral bronchiolitis and pneumonia worldwide. Such a disease is characterized by an infection of epithelial cells of the distal airways that leads to inflammation and subsequently to respiratory failure. Upon infection, different pattern recognition receptors recognize the virus and trigger the innate immune response against the hRSV. Further, T cell immunity plays an important role for virus clearance. Based on animal studies, it is thought that the host immune response to hRSV is based on a biased T helper (Th)-2 and Th17 T cell responses with the recruitment of T cells, neutrophils and eosinophils to the lung, causing inflammation and tissue damage. In contrast, human immunity against RSV has been shown to be more complex with no definitive T cell polarization profile. Nowadays, only a humanized monoclonal antibody, known as palivizumab, is available to protect against hRSV infection in high-risk infants. However, such treatment involves several injections at a significantly high cost. For these reasons, intense research has been focused on finding novel vaccines or therapies to prevent hRSV infection in the population. Here, we comprehensively review the recent literature relative to the immunological features during hRSV infection, as well as the new insights into preventing the disease caused by this virus.

Defining the Risk and Associated Morbidity and Mortality of Severe Respiratory Syncytial Virus Infection Among Preterm Infants Without Chronic Lung Disease or Congenital Heart 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 second publication covers the risk and burden of RSV infection in preterm infants born at <37 weeks' gestational age (wGA) without chronic lung disease or congenital heart disease.

METHODS

A systematic review was undertaken for articles published between January 1, 1995 and December 31, 2015. Studies reporting data for hospital visits/admissions for RSV infection among preterm infants 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.

RESULTS

2469 studies were identified of which 85 were included. Preterm infants, particularly those born at lower wGA, tended to have higher RSV hospitalization (RSVH) rates compared with otherwise healthy term infants (high SOE). RSVH rates ranged from ~5 per 1000 children to >100 per 1000 children with the highest rates shown in the lowest gestational age infants (high SOE). Independent risk factors associated with RSVH include: proximity of birth to the RSV season, living with school-age siblings, smoking of mother during pregnancy or infant exposure to environmental smoking, reduced breast feeding, male sex, and familial atopy (asthma) (high SOE). Predictive models can identify 32/33-35 wGA infants at risk of RSVH (high SOE).

CONCLUSION

RSV infection remains a major burden on Western healthcare systems and is associated with significant morbidity. Further studies focusing on the prevalence and burden of RSV in different gestational age cohorts, the changing risk of RSVH during the first year of life, and on RSV-related mortality in preterm infants are needed to determine the true burden of disease.

FUNDING

AbbVie.

Risk of Readmission for Wheezing during Infancy in Children with Congenital Diaphragmatic Hernia

RATIONALE

Congenital diaphragmatic hernia (CDH) is associated with a high incidence of respiratory problems, even after initial hospital discharge. These problems are likely to lead to re-hospitalization during infancy, although actual frequency of readmissions is unknown.

OBJECTIVE

We aimed to determine the rate of hospitalization for wheezing in infants with CDH between the time of initial discharge and 24 months of age, and to identify factors associated with readmission.

METHODS

Data about infants with CDH born in three French reference tertiary centers between January 2009 and March 2013 who were alive at hospital discharge, were extracted from a prospective national database.

RESULTS

Ninety-two children were identified, and 86 were included in the analysis. In total, 116 wheezing episodes requiring a doctor's visit occurred in 50 infants (58%) before 24 months of age. Twenty-two children (26%) were readmitted at least once for wheezing exacerbations. RSV was present in 6 of 15 (40%) of children with available nasal samples at first readmission, and 1 of 5 (20%) at second readmission. Thoracic herniation of the liver, low gestational age, longer initial hospitalization, need for oxygen therapy at home, and eczema were all significantly associated with readmission for wheezing exacerbations. Fifty-three infants (62%) received palivizumab prophylaxis, but there was no association with the overall rate of readmission for wheezing exacerbations or RSV-related hospitalization.

CONCLUSIONS

The rate of readmission for wheezing among infants with CDH is high, and significantly influenced by several prenatal and neonatal factors. Palivizumab prophylaxis was not associated with the rate of readmission.

Trends in respiratory syncytial virus bronchiolitis hospitalizations in children less than 1 year: 2004-2012

OBJECTIVE

To analyze trends in health outcomes and the influence of risk factors in children under 1 year with acute bronchiolitis due to respiratory syncytial virus (RSV bronchiolitis). A risk-adjustment model for RSV bronchiolitis in-hospital mortality was also developed.

RESEARCH DESIGN AND METHODS

Retrospective study of hospitalizations for RSV bronchiolitis in children aged <1 year from 2004 to 2012. We used nationally representative data from the Spanish National Health Service records.

RESULTS

Over the study period, the annual hospital discharges for RSV bronchiolitis ranged between 6390 and 8637. The annual in-hospital mortality rate ranged from 120 (2004) to 69 (2012) per 100,000 hospitalizations and the mean length of stay decreased steadily from 6.5 to 5.2 days (p < 0.001); 98.3% of hospitalizations for RSV bronchiolitis were children without risk factors. The in-hospital mortality rate due to RSV bronchiolitis in children with risk factors was 18.8 times higher than non-high-risk children and, in adjusted analyses, the OR of in-hospital mortality due to RSV bronchiolitis was higher than that due to other causes.

LIMITATIONS

This study is a retrospective analysis, based on administrative data. It does not include data about pre- or in-hospital treatments, and has the limitations inherent in procedures for determining risk-adjusted mortality rates. Socioeconomic and environmental factors have not been considered in this study.

CONCLUSIONS

RSV bronchiolitis is a leading cause of hospitalizations for infants under 1 year and has not shown incidence reduction over a 9 year period. Risk factors increase the in-hospital mortality risk and it is higher if the hospitalization cause is RSV bronchiolitis than any other reason.

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.

Safety and pharmacokinetics of extended use of palivizumab in Saudi Arabian infants and children

BACKGROUND

The peak season of respiratory syncytial virus (RSV) infections in warmer climates may extend beyond the typical five-month RSV season of temperate regions. Additional monthly doses of palivizumab may be necessary in warmer regions to protect children at high risk for serious infection by the RSV.

METHODS

In a Phase II, single-arm, single-center, non-comparative, open-label, prospective study conducted in Saudi Arabia, children at high risk for RSV infection received up to seven monthly injections of palivizumab (15 mg/kg) during the 2000-2001 RSV season. Key enrollment criteria were no previous exposure to palivizumab and gestational age ≤35 weeks, ≤6 months of age at enrollment, or chronic lung disease and ≤24 months of age at enrollment. We wished to assess the safety, immunogenicity, and pharmacokinetics of palivizumab as an extended seven-dose regimen.

RESULTS

Of 18 enrolled patients, 17 patients received seven palivizumab injections. Seven adverse events (AEs) occurred in five patients. Bronchiolitis was the most commonly reported AE. Six serious AEs occurred in four patients. No AEs were considered related to palivizumab. Trough levels of palivizumab in serum were >40 μg/mL in most patients after the first injection and in 16/18 and 14/17 patients after the fourth and sixth injections, respectively. Except for one patient at one visit, the anti-palivizumab titer was <1:10 at all visits.

CONCLUSION

These data suggest that an extended palivizumab regimen of up to seven monthly doses during the RSV season exhibited an acceptable safety profile in children at high risk for RSV infection in Saudi Arabia.

Clinical characteristics and risk factors of severe respiratory syncytial virus-associated acute lower respiratory tract infections in hospitalized infants

BACKGROUND

To investigate the clinical characteristics and analyze risk factors for severe respiratory syncytial virus (RSV) infection in hospitalized infants with acute lower respiratory tract infections (ALRIs).

METHODS

A retrospective review of the medical records of infants with RSV-associated ALRIs between March 1st, 2011 and February 29th, 2012 was conducted. Subjects were followed up over the phone or by outpatient visit six and twelve months after discharge.

RESULTS

Among 913 RSV-associated ALRIs infants, 288 (31.5%) had severe infections, which accounted for 4.2% of hospitalized children. The hospital RSV mortality rate was 1.0%. The proportions of cases with tachypnea, apnea, cyanosis, and fine rales were significantly higher in the severe ALRIs group (all P<0.001). Multivariate logistic regression showed that low-birth-weight [1.698 (1.028-2.805)], age less than 3 months old [3.385 (2.174-5.271)], congenital heart disease [1.667 (1.149-2.418)], bronchopulmonary dysplasia [8.505 (1.731-41.780)], and airway abnormalities [2.246 (1.008-5.005)] were independent risk factors for severe ALRIs. The incidence of bronchitis, pneumonia and readmission in the severe group was significantly higher than that of the non-severe group during the one-year follow-up (all P<0.001).

CONCLUSIONS

Younger age, low birth weight and underlying disease are associated with severe RSVassociated ALRIs. Furthermore, severe RSV infections may be associated with a higher frequency of subsequent bronchitis, pneumonia and re-hospitalization in the following year.