Respiratory syncytial virus: diagnosis, prevention and management

Identifying the panorama of potential pandemic pathogens and their key characteristics: a systematic scoping review

The globe has recently seen several terrifying pandemics and outbreaks, underlining the ongoing danger presented by infectious microorganisms. This literature review aims to explore the wide range of infections that have the potential to lead to pandemics in the present and the future and pave the way to the conception of epidemic early warning systems. A systematic review was carried out to identify and compile data on infectious agents known to cause pandemics and those that pose future concerns. One hundred and fifteen articles were included in the review. They provided insights on 25 pathogens that could start or contribute to creating pandemic situations. Diagnostic procedures, clinical symptoms, and infection transmission routes were analyzed for each of these pathogens. Each infectious agent's potential is discussed, shedding light on the crucial aspects that render them potential threats to the future. This literature review provides insights for policymakers, healthcare professionals, and researchers in their quest to identify potential pandemic pathogens, and in their efforts to enhance pandemic preparedness through building early warning systems for continuous epidemiological monitoring.

Clinical and economic inpatient burden of respiratory syncytial virus (RSV) infections in children < 2 years of age in Germany, 2014-2019: a retrospective health claims analysis

BACKGROUND

Respiratory syncytial virus (RSV) is a common cause for severe lower respiratory tract infections (LRTI) in children < 2 years of age in Germany - though little is known about the clinical and economic burden of RSV in children with and without risk factors per month of life.

METHODS

In a retrospective health claims analysis, we identified RSV inpatient cases between 2014 and 2019. We assessed incidence rates, mortality rate, healthcare resource utilization, associated direct costs per case and excess costs for 30, 90 and 365 days after hospital admission matched to a control group. The outcomes are reported separately for the first and second year of life (i.e., for infants and toddlers) and were stratified by month of life, preterm and risk status (i.e., presence of underlying disease: chronic respiratory or cardiac disease, immunosuppression, neurological diseases, diabetes, conditions originating in the perinatal period).

RESULTS

RSV-attributable hospital incidence rate was higher in infants (30.25/1,000) than toddlers (14.52/1,000), highest in the first three months of life (44.21/1,000), in infants born preterm (64.76/1,000) or with any underlying disease (54.85/1,000). Mortality rate was also higher for infants (0.08/1,000) than toddlers (0.04/1,000). Mean 30-day excess costs ranged from 2,953 € for infants born full-term at no risk, hospitalized for 5 days, to 6,694 € for infants born extremely premature, hospitalized for 7 days.

CONCLUSION

In Germany, the clinical and economic burden of RSV is substantial, especially in the most vulnerable population, that is, very young infants, those born premature and/or those with an underlying disease.

Clinical Characteristics of Virologically Confirmed Respiratory Syncytial Virus in English Primary Care: Protocol for an Observational Study of Acute Respiratory Infection

BACKGROUND

There are gaps in our understanding of the clinical characteristics and disease burden of the respiratory syncytial virus (RSV) among community-dwelling adults. This is in part due to a lack of routine testing at the point of care. More data would enhance our assessment of the need for an RSV vaccination program for adults in the United Kingdom.

OBJECTIVE

This study aimed to implement point-of-care-testing (POCT) in primary care to describe the incidence, clinical presentation, risk factors, and economic burden of RSV among adults presenting with acute respiratory infection.

METHODS

We are recruiting up to 3600 patients from at least 21 practices across England to participate in the Royal College of General Practitioners Research Surveillance Centre. Practices are selected if they undertake reference virology sampling for the Royal College of General Practitioners Research Surveillance Centre and had previous experience with respiratory illness studies. Any adult, ≥40 years old, presenting with acute respiratory infection with onset ≤10 days, but without RSV within the past 28 days, will be eligible to participate. We will estimate the incidence proportion of RSV, describe the clinical features, and risk factors of patients with RSV infection, and measure the economic burden of RSV infection.

RESULTS

A total of 25 practices across different English health administrative regions expressed interest and were recruited to participate. We have created and tested an educational program to deploy POCT for RSV in primary care. In addition to using the POCT device, we provide suggestions about how to integrate POCT into primary care workflow and templates for high-quality data recording of diagnosis, symptoms, and signs. In the 2023-2024 winter RSV detection in the sentinel network grew between October and late November. According to data from the UK Health Security Agency, the peak RSV swab positivity was in International Standards Organization week 48, 2023. Data collection remains ongoing, and results from the subset of practices participating in this study are not yet available.

CONCLUSIONS

This study will provide data on the RSV incidence in the community as well as rapid information to inform sentinel surveillance and vaccination programs. This information could potentially improve clinical decision-making.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/60669.

Respiratory syncytial virus: A review of current basic and clinical knowledge

Background

Respiratory syncytial virus (RSV) is a highly contagious pathogen known for causing respiratory tract infections, particularly among pediatric and elderly patients. Its ability to induce outbreaks in both community and hospital settings underscores its substantial health burden. This review aims to provide a comprehensive understanding of RSV, including its biological and clinical aspects.

Methods

A comprehensive review of the literature was conducted by searching PubMed, Scopus, and Web of Science databases for relevant articles. Key topics included RSV virology, epidemiology, clinical findings, diagnostic methods, management approaches, and preventive strategies.

Results

This review encompasses the taxonomy and structure of RSV, including its genome and proteins. Various strains and their dominance patterns, alongside pathogenesis mechanisms, are explored. Diagnostic techniques such as nucleic acid amplification tests are discussed for their efficacy and accessibility. Supportive care remains the primary treatment, with antiviral therapies playing a limited role. Monoclonal antibody immunization and vaccination efforts offer promising avenues for RSV prevention. The impact of the COVID-19 pandemic on RSV epidemiology is also considered, along with the oncolytic potential of RSV in cancer treatment.

Conclusion

Advancements in understanding RSV virology, epidemiology, and clinical management have paved the way for improved diagnostic and preventive strategies. However, challenges remain in ensuring widespread access to diagnostics and effective treatments, particularly in resource-limited settings. Continued research and global collaboration are essential for addressing the ongoing impact of RSV and reducing its burden on public health.

Respiratory Syncytial Virus: A WAidid Consensus Document on New Preventive Options

Background/Objectives: Respiratory syncytial virus (RSV) is a leading cause of respiratory infections, particularly affecting young infants, older adults, and individuals with comorbidities. Methods: This document, developed as a consensus by an international group of experts affiliated with the World Association of Infectious Diseases and Immunological Disorders (WAidid), focuses on recent advancements in RSV prevention, highlighting the introduction of monoclonal antibodies (mAbs) and vaccines. Results: Historically, RSV treatment options were limited to supportive care and the monoclonal antibody palivizumab, which required multiple doses. Recent innovations have led to the development of long-acting mAbs, such as nirsevimab, which provide season-long protection with a single dose. Nirsevimab has shown high efficacy in preventing severe RSV-related lower respiratory tract infections (LRTIs) in infants, reducing hospitalizations and ICU admissions. Additionally, new vaccines, such as RSVpreF and RSVpreF3, target older adults and have demonstrated significant efficacy in preventing LRTIs in clinical trials. Maternal vaccination strategies also show promise in providing passive immunity to newborns, protecting them during the most vulnerable early months of life. This document further discusses the global burden of RSV, its economic impact, and the challenges of implementing these preventative strategies in different healthcare settings. Conclusions: The evidence supports the integration of both passive (mAbs) and active (vaccines) immunization approaches as effective tools to mitigate the public health impact of RSV. The combined use of these interventions could substantially reduce RSV-related morbidity and mortality across various age groups and populations, emphasizing the importance of widespread immunization efforts.

Retrospective Analysis of RSV Infection in Pediatric Patients: Epidemiology, Comorbidities, Treatment, and Costs in Dubai (2014-2023)

Background: Infections attributable to respiratory syncytial virus (RSV) are a major cause of hospitalization among young children worldwide. Despite substantial clinical and economic burden, real-world data associated with RSV infections in the United Arab Emirates (UAE) are limited. Objectives: This study aimed to assess among children (<18 years) diagnosed with RSV the epidemiology, seasonality, comorbidities, treatment patterns, length of hospital stay, healthcare resource utilization (HCRU), and costs associated with pediatric infection in Dubai, UAE. Methods: This 10-year retrospective cohort study (Jan. 1, 2014-Sept. 30, 2023) utilized Dubai Real-World Database, a private insurance claims database. Patients aged <18 years with a first-episode diagnosis claim (primary or secondary, or a hospital admission) for RSV any time during the index period (Jan. 1, 2014-June 30, 2023) were included. Outcomes were analyzed during a 3-month follow-up. Patients were stratified into 3 cohorts: Cohort 1 (<2 years), Cohort 2 (2 to <6 years), and Cohort 3 (6 to <18 years). Results: Of 28 011 patients identified, 25 729 were aged <18 years with RSV infection. An increasing trend in reported cases was observed from 2014 to 2022, with an average annual increase of 55%. Half of study patients (49.3%) belonged to Cohort 1, with a mean age of 0.6 years, while less than 2% had known risk factors and 22% of the patients in cohort 1 were hospitalized. In Cohort 1, 32.0% had upper respiratory tract infections, 39.4% had lower respiratory tract infections, and 44.4% of patients had an "other respiratory disease." The average length of hospitalization was about 4 days across all cohorts. The total hospitalization cost was highest in patients <2 years, amounting to US 9   798   174 ( m e d i a n , U S 2241.30). Conclusion: Among the RSV patients, 49.3% were <2 years of age and few had recognized risk factors. Among patients <2 years, 22% were hospitalized, with an average hospital stay of 4 days; the cost of hospitalization totaled US $9 798 174. These findings can inform healthcare stakeholders about future policy measures and the need for effective preventive strategies.

Natural Binary Herbal Small Molecules Self-Assembled Nanogel for Synergistic Inhibition of Respiratory Syncytial Virus

Respiratory syncytial virus (RSV) is one of the most significant pathogenic infections in childhood, associated with high morbidity and mortality rates. Currently, there is no effective and safe drug or vaccine available for RSV. Glycyrrhizic acid (GA), an active compound derived from the natural herb licorice, has been reported to provide protection against influenza and coronaviruses, exhibiting notable antiviral and anti-inflammatory properties. Ephedrine (EPH) is a commonly prescribed medication for the treatment of cough and asthma, and it also demonstrates certain antiviral effects. In this study, EPH and GA were combined to form an efficient nanomaterial (EPH-GA nanogel). The self-assembly of this nanogel is driven by hydrogen bonding and hydrophobic interactions, allowing it to serve as an antiviral nanomedicine without the need for a dual-component carrier, achieving a 100% drug loading efficiency. Oral administration of the EPH-GA nanogel significantly reduced viral load in the lungs of mice and improved lung lesions and tissue infiltration caused by RSV. Notably, we discovered that the assembled drug may create a "physical barrier" that prevents RSV from adsorbing to host cells, while free GA and EPH may compete with RSV for protein binding sites, thereby enhancing cellular uptake of EPH. Consequently, this prevents RSV infection and proliferation within host cells. Furthermore, the EC50 values changed from 310.83 μM for EPH and 262.88 μM for GA to 68.25 μM for the EPH-GA combination, with a combination index of 0.458. In addition, the in vivo biopharmaceutic process of GA and EPH was investigated, revealing that the oral administration of EPH-GA significantly increased the bioavailability of EPH while maintaining its plasma concentration at a relatively stable level. This enhancement may contribute to a synergistic antiviral effect when combined with GA. Furthermore, the in vivo process of EPH-GA demonstrates the advantage of delivering the drug to the lesion at elevated levels, thereby facilitating its antiviral mechanism at the cellular level. In this study, we identified an effective nanomedicine, EPH-GA nanogel, which can inhibit the proliferation of RSV and mitigate lung lesions resulting from viral infection by influencing the biopharmaceutical process in vivo. This research not only offers a novel strategy for the nanomedicine treatment of RSV but also elucidates, to some extent, the compatibility mechanisms of the multicomponents of traditional Chinese medicine.

Respiratory syncytial virus: an overview of clinical manifestations and management in the Indian pediatric population

Respiratory syncytial virus (RSV) plays a major part in causing lower respiratory tract infections in younger populations, especially in infants and pediatric patients, causing a higher rate of morbidity and mortality in the respective population, affecting 60% of the population globally. Typically, identifying the virus in the patient's respiratory secretions is important for laboratory validation of a clinically suspected RSV infection. Unfortunately, the only available preventive measure to lower the incidence for infants who are at high risk of RSV-induced hospitalization is palivizumab prophylaxis. Treatment strategies to manage RSV involve using an antiviral drug that is Ribavirin along with bronchodilators, nebulized adrenaline (epinephrine), and nebulized hypertonic saline. Providing patients with alternative treatment options like vitamin D-cathelicidin as well as probiotics and prebiotics can help reduce the intensity of the infection. This review article focuses on the epidemiology, clinical manifestation, prophylaxis, and available treatment options for RSV infections in infants, children, and young adults.

Computational Analysis of the Accumulation of Mutations in Therapeutically Important RNA Viral Proteins During Pandemics with Special Emphasis on SARS-CoV-2

Single stranded RNA viruses are primary causative agents for pandemics, causing extensive morbidity and mortality worldwide. A pivotal question in pandemic preparedness and therapeutic intervention is what are the specific mutations which are more likely to emerge during such global health crises? This study aims to identify markers for mutations with the highest probability of emergence in these pandemics, focusing on the SARS-CoV-2 spike protein, an essential and therapeutically significant viral protein, starting from sequence information from the onset of the pandemic until July 2022. Quite consistently, we observed that emerged mutations tended to demonstrate a high genetic score, which reflects high similarity of the type of codon required for translation between an amino acid and to the mutated one. Further, this pattern is also observed in therapeutically significant proteins of other ssRNA pandemic viruses, including influenza (HA, NA), spike proteins of Ebola, envelope of Dengue and Chikungunya. We propose that the genetic score serves as an initial indicator, preceding the actual impact of the mutation on viral fitness. Finally, we developed a comprehensive computational pipeline to further explore and predict the subsequent effects of mutations on viral fitness. We believe that our pipeline can narrow down and predict future mutations in therapeutically important viral proteins during a pandemic.

Modelling the potential clinical and economic impact of universal immunisation with nirsevimab versus standard of practice for protecting all neonates and infants in their first respiratory syncytial virus season in Spain

BACKGROUND

Respiratory syncytial virus (RSV) is associated with substantial morbidity among infants. This study modelled the potential public health and economic impact of nirsevimab, a long-acting monoclonal antibody, as an immunoprophylactic strategy for all infants in Spain in their first RSV season.

METHODS

A static decision-analytic model of the Spanish birth cohort during its first RSV season was developed to estimate the impact of nirsevimab on RSV-related health events and costs versus the standard of practice (SoP). Spain-specific costs and epidemiological data were used as model inputs. Modelled outcomes included RSV-related outpatient visits, emerging room (ER) visits, hospitalisations - including pediatric intensive care unit (PICU) admission, mechanical ventilation, and inpatient mortality.

RESULTS

Under the current SoP, RSV caused 151,741 primary care visits, 38,798 ER visits, 12,889 hospitalisations, 1,412 PICU admissions, and 16 deaths over a single season, representing a cost of €71.8 million from a healthcare payer perspective. Universal immunisation of all infants with nirsevimab was expected to prevent 97,157 primary care visits (64.0% reduction), 24,789 ER visits (63.9%), 8,185 hospitalisations (63.5%), 869 PICU admissions (61.5%), and 9 inpatient deaths (52.6%), saving €47.8 million (62.4%) in healthcare costs.

CONCLUSIONS

These results suggest that immunisation with nirsevimab of all infants experiencing their first RSV season in Spain is likely to prevent thousands of RSV-related health events and save considerable costs versus the current SoP.

Disease Burden of RSV Infections and Bronchiolitis in Young Children (< 5 Years) in Primary Care and Emergency Departments: A Systematic Literature Review

Respiratory syncytial virus (RSV) is the most common cause of acute respiratory infections in young children. Limited data are available on RSV disease burden in primary care and emergency departments (EDs). This review synthesizes the evidence on population-based incidence rates of RSV infections in young children (< 5 years) in primary care and EDs. A systematic literature review was performed in PubMed and Embase. Studies reporting yearly population-based RSV incidence rates in primary care and EDs were included. A total of 4244 records were screened and 32 studies were included, conducted between 1993 and 2019. Studies were mainly performed in high-income countries (n = 27), with 15 studies in North America and 10 studies in Europe. There was significant variability in study methodology and setting among studies, resulting in considerable variability in reported incidence rates. Incidence rates were higher in primary care-ranging from 0.8 to 330 (median = 109) per 1000 population-compared to EDs (7.5-144.0, median = 48). The highest incidence rates were reported in infants. Additionally, incidence rates were higher in high-income countries and in studies using laboratory-confirmed RSV cases compared to studies using bronchiolitis ICD-codes (non-laboratory confirmed). Our study found that a substantial number of children under 5 years of age attend primary care settings and EDs, every year for RSV infections. Due to the considerable heterogeneity in study methodology, it was impossible to draw definitive conclusions regarding factors explaining differences in reported incidence rates. Additionally, more studies in low- and middle-income countries are recommended.

Epidemiology, Outcomes, and Trend Analysis of Hospitalized Infants With Respiratory Syncytial Virus (RSV) Bronchiolitis From 1997 to 2019

Background  Most children with respiratory syncytial virus (RSV) infection have a self-limiting course that can be managed with supportive care, and hospitalization is uncommon. The objectives of this study were to evaluate the epidemiology, outcomes, associated comorbidities, and temporal trends in the prevalence of infants one to 24 months of age who required hospitalization for RSV infection in the United States of America from 1997 to 2019. Methods In this retrospective cross-sectional study, we utilized the Kids' Inpatient Database (KID) to investigate the prevalence and outcomes of RSV bronchiolitis within a large cohort of discharged patients from 1997 to 2019. We included children one to 24 months of age admitted with a diagnosis of RSV bronchiolitis. Neonates were excluded from the analysis. A chi-square for linear trend was used to analyze trends in the prevalence of RSV bronchiolitis hospitalization, the presence of complex chronic conditions (CCC), congenital heart disease (CHD), the use of non-invasive and invasive mechanical ventilation (NIV and IMV), and hospital mortality. Results There were a total of 566,786 infants aged one to 24 months hospitalized with RSV infection out of a total of 9,309,597 discharges during the eight-year cohort, with a hospital prevalence of 60.9 per 1000 discharges and a hospital mortality rate of 0.09% (95% confidence interval (CI): 0.08%-0.1%). There was no trend in hospitalization rates of RSV infections per 100,000 U.S. population during the study period, with a decrease in hospital mortality trend. Children with RSV bronchiolitis were more likely to have government insurance and reside in zip codes with the lowest income quartile. There was a significant seasonal and regional variation in RSV-related hospitalizations. The presence of CCC was identified in 2.4% of the RSV group compared to 5.1% of non-RSV discharges (odds ratio (OR): 0.46, 95% CI: 0.45-0.47; p<0.001). The prevalence of RSV among all discharges has significantly increased over the study period, rising from 51.6 cases per 1000 discharges in 1997 to 180.1 cases per 1000 discharges in 2019 (p<0.001). The prevalence of CCC and CHD among RSV patients has also shown an upward trend, with CCC cases increasing from 1,411 in 1997 to 2,795 in 2019 and CHD cases rising from 1,795 to 3,622 during the same period. The use of invasive mechanical ventilation, non-invasive ventilation, and extracorporeal membrane oxygenation has consistently increased over time. Additionally, complications such as the need for cardiopulmonary resuscitation have demonstrated a similar increasing trend, although they have remained overall low. However, population-based hospitalization rates showed no significant trend. Conclusions The hospitalization rates at a population level in the United States for RSV infection in children aged one to 24 months remained steady from 1997 to 2019, while hospital mortality rates showed a declining trend. There is an increased proportion of comorbid conditions and increased resource utilization in children with RSV. These findings are important for monitoring the effectiveness of preventive strategies for severe RSV infections.

Cost-effectiveness Analysis of Maternal Immunization with RSVpreF Vaccine for the Prevention of Respiratory Syncytial Virus Among Infants in Spain

INTRODUCTION

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory infections (ALRI) in children under one year of age. In high-income countries, RSV infections cause a significant overload of care every winter, imposing a significant burden to the healthcare system, which has made the development of prevention strategies a major global health priority. In this context, a new bivalent RSV prefusion F protein-based vaccine (RSVpreF) has recently been approved. The objective of this study was to evaluate the cost-effectiveness of vaccinating pregnant women with the RSVpreF vaccine to prevent RSV in infants from the Spanish National Healthcare System (NHS) perspective.

METHODS

A hypothetical cohort framework and a Markov-type process were used to estimate clinical outcomes, costs, quality-adjusted life years (QALY) and cost-per-QALY gained (willingness-to-pay threshold: €25,000/QALY) for newborn infants born to RSV-vaccinated versus unvaccinated mothers over an RSV season. The base case analysis was performed from the NHS perspective including direct costs (€2023) and applying a discount of 3% to future costs and outcomes. To evaluate the robustness of the model, several scenarios, and deterministic and probabilistic analyses were carried out. All the parameters and assumptions were validated by a panel of experts.

RESULTS

The results of the study showed that year-round maternal vaccination program with 70% coverage is a dominant option compared to no intervention, resulting in direct cost savings of €1.8 million each year, with an increase of 551 QALYs. Maternal vaccination could prevent 38% of hospital admissions, 23% of emergency room visits, 19% of primary care visits, and 34% of deaths due to RSV. All scenario analyses showed consistent results, and according to the probabilistic sensitivity analysis (PSA), the probability of maternal vaccination being cost-effective versus no intervention was 99%.

CONCLUSIONS

From the Spanish NHS perspective, maternal vaccination with bivalent RSVpreF is a dominant alternative compared with a non-prevention strategy.

Pre-COVID-19-pandemic RSV epidemiology and clinical burden in pediatric primary care in Italy: a comparative analysis across two regions for the 2019/2020 season

BACKGROUND

Respiratory syncytial virus (RSV) infection in children under 5 years have a significant clinical burden, also in primary care settings. This study investigates the epidemiology and burden of RSV in Italian children during the 2019/20 pre-pandemic winter season.

METHODS

A prospective cohort study was conducted in two Italian regions. Children with Acute Respiratory Infection (ARI) visiting pediatricians were eligible. Nasopharyngeal swabs were collected and analyzed via multiplex PCR for RSV detection. A follow-up questionnaire after 14 days assessed disease burden, encompassing healthcare utilization and illness duration. Statistical analyses, including regression models, explored associations between variables such as RSV subtype and regional variations.

RESULTS

Of 293 children with ARI, 41% (119) tested positive for RSV. Median illness duration for RSV-positive cases was 7 days; 6% required hospitalization (median stay: 7 days). Medication was prescribed to 95% (110/116) of RSV cases, with 31% (34/116) receiving antibiotics. RSV subtype B and regional factors predicted increased healthcare utilization. Children with shortness of breath experienced a 36% longer illness duration.

CONCLUSIONS

This study highlights a significant clinical burden and healthcare utilization associated with RSV in pre-pandemic Italian primary care settings. Identified predictors, including RSV subtype and symptomatology, indicate the need for targeted interventions and resource allocation strategies. RSV epidemiology can guide public health strategies for the implementation of preventive measures.

RSV Disease Burden in Primary Care in Italy: A Multi-Region Pediatric Study, Winter Season 2022-2023

INTRODUCTION

Human respiratory syncytial virus (RSV) is one of the most frequent causes of respiratory infections in children under 5 years of age, but its socioeconomic impact and burden in primary care settings is still little studied.

METHODS

During the 2022/2023 winter season, 55 pediatricians from five Italian regions participated in our community-based study. They collected a nasal swab for RSV molecular test from 650 patients under the age of 5 with acute respiratory infections (ARIs) and performed a baseline questionnaire. The clinical and socioeconomic burden of RSV disease in primary care was evaluated by two follow-up questionnaires completed by the parents of positive children on Days 14 and 30.

RESULTS

RSV laboratory-confirmed cases were 37.8% of the total recruited ARI cases, with RSV subtype B accounting for the majority (65.4%) of RSV-positive swabs. RSV-positive children were younger than RSV-negative ones (median 12.5 vs. 16.5 months). The mean duration of symptoms for all children infected by RSV was 11.47 ± 6.27 days. We did not observe substantial differences in clinical severity between the two RSV subtypes, but RSV-A positive patients required more additional pediatric examinations than RSV-B cases. The socioeconomic impact of RSV infection was considerable, causing 53% of children to be absent from school, 46% of parents to lose working days, and 25% of families to incur extra costs.

CONCLUSIONS

Our findings describe a baseline of the RSV disease burden in primary care in Italy before the introduction of upcoming immunization strategies.

Strategies to Reduce the Burden of Respiratory Syncytial Virus Infections in Children in Portugal: Results from the Focus Group RSV Think Tank

N/a.

Inhaled "Muco-Trapping" Monoclonal Antibody Effectively Treats Established Respiratory Syncytial Virus (RSV) Infections

Respiratory syncytial virus (RSV) causes substantial morbidity and mortality in infants, the immunocompromised, and the elderly. RSV infects the airway epithelium via the apical membrane and almost exclusively sheds progeny virions back into the airway mucus (AM), making RSV difficult to target by systemically administered therapies. An inhalable "muco-trapping" variant of motavizumab (Mota-MT), a potent neutralizing mAb against RSV F is engineered. Mota-MT traps RSV in AM via polyvalent Fc-mucin bonds, reducing the fraction of fast-moving RSV particles in both fresh pediatric and adult AM by ≈20-30-fold in a Fc-glycan dependent manner, and facilitates clearance from the airways of mice within minutes. Intranasal dosing of Mota-MT eliminated viral load in cotton rats within 2 days. Daily nebulized delivery of Mota-MT to RSV-infected neonatal lambs, beginning 3 days after infection when viral load is at its maximum, led to a 10 000-fold and 100 000-fold reduction in viral load in bronchoalveolar lavage and lung tissues relative to placebo control, respectively. Mota-MT-treated lambs exhibited reduced bronchiolitis, neutrophil infiltration, and airway remodeling than lambs receiving placebo or intramuscular palivizumab. The findings underscore inhaled delivery of muco-trapping mAbs as a promising strategy for the treatment of RSV and other acute respiratory infections.

Evaluation of antibody-based preventive alternatives for respiratory syncytial virus: a novel multi-criteria decision analysis framework and assessment of nirsevimab in Spain

BACKGROUND

Respiratory syncytial virus (RSV) is a highly infectious disease that poses a significant clinical and medical burden, as well as social disruption and economic costs, recognized by the World Health Organization as a public health issue. After several failed attempts to find preventive candidates (compounds, products, including vaccines), new alternatives might be available, one being nirsevimab, the first and only option approved for RSV prevention in neonates and infants during their first RSV season. The objective of this study was to develop a novel multi-criteria decision analysis (MCDA) framework for RSV antibody-based preventive alternatives and to use it to assess the value of nirsevimab vs. placebo as a systematic immunization approach to prevent RSV in neonates and infants during their first RSV season in Spain.

METHODS

Based on a pre-established model called Vaccinex, an ad-hoc MCDA framework was created to reflect relevant attributes for the assessment of current and future antibody-based preventive measures for RSV. The estimated value of nirsevimab was obtained by means of an additive linear model combining weights and scores assigned by a multidisciplinary committee of 9 experts. A retest and three sensitivity analyses were conducted.

RESULTS

Nirsevimab was evaluated through a novel framework with 26 criteria by the committee as a measure that adds value (positive final estimated value: 0.56 ± 0.11) to the current RSV scenario in Spain, by providing a high efficacy for prevention of neonates and infants. In addition, its implementation might generate cost savings in hospitalizations and to the healthcare system and increase the level of public health awareness among the general population, while reducing health inequities.

CONCLUSIONS

Under a methodology with increasing use in the health field, nirsevimab has been evaluated as a measure which adds value for RSV prevention in neonates and infants during their first RSV season in Spain.

Arexvy: A Comprehensive Review of the Respiratory Syncytial Virus Vaccine for Revolutionary Protection

The respiratory syncytial virus (RSV) is a major cause of acute lower respiratory tract infection in children and poses a significant risk to older adults. Developing a vaccine against RSV has been a priority, and the recently approved Arexvy vaccine has shown promise in preventing lower respiratory tract disease (LRTD) caused by RSV in individuals aged 60 years and older. This comprehensive review discusses the history of RSV, challenges in vaccine development, and the mechanism of action of Arexvy. The efficacy and safety of the vaccine are explored based on phase 3 clinical trial, demonstrating its effectiveness in preventing RSV-associated LRTD. The most common adverse reactions reported include injection site pain, fatigue, myalgia, headache, and arthralgia. Ongoing research focuses on the long-term effectiveness of Arexvy, including the need for booster doses and its impact on reducing RSV-associated hospitalizations. The potential of Arexvy to lessen the burden of RSV-related illnesses, particularly in vulnerable populations, is highlighted, emphasizing the importance of widespread immunization efforts and accessibility to this groundbreaking vaccine.

Controlled Human Infection Challenge Studies with RSV

Despite considerable momentum in the development of RSV vaccines and therapeutics, there remain substantial barriers to the development and licensing of effective agents, particularly in high-risk populations. The unique immunobiology of RSV and lack of clear protective immunological correlates has held back RSV vaccine development, which, therefore, depends on large and costly clinical trials to demonstrate efficacy. Studies involving the deliberate infection of human volunteers offer an intermediate step between pre-clinical and large-scale studies of natural infection. Human challenge has been used to demonstrate the potential efficacy of vaccines and antivirals while improving our understanding of the protective immunity against RSV infection. Early RSV human infection challenge studies determined the role of routes of administration and size of inoculum on the disease. However, inherent limitations, the use of highly attenuated/laboratory-adapted RSV strains and the continued evolutionary adaptation of RSV limits extrapolation of results to present-day vaccine testing. With advances in technology, it is now possible to perform more detailed investigations of human mucosal immunity against RSV in experimentally infected adults and, more recently, older adults to optimise the design of vaccines and novel therapies. These studies identified defects in RSV-induced humoral and CD8+ T cell immunity that may partly explain susceptibility to recurrent RSV infection. We discuss the insights from human infection challenge models, ethical and logistical considerations, potential benefits, and role in streamlining and accelerating novel antivirals and vaccines against RSV. Finally, we consider how human challenges might be extended to include relevant at-risk populations.

POU Class 2 Associating Factor 1 Exerts a Protective Effect on the Respiratory Syncytial Virus-Induced Acute Bronchiolitis by the NF-κB Pathway

Background

Respiratory syncytial virus (RSV) is the main pathogen causing acute bronchiolitis, which is common in infants and young children. A previous study revealed the possible involvement of POU class 2 associating factor 1 (POU2AF1) in RSV-triggered acute bronchiolitis. We attempted to clarify the specific action mechanism of POU2AF1 underlying RSV-triggered inflammation.

Methods

RT-qPCR measured POU2AF1 levels in RSV-infected children, mice, and airway epithelial cell lines (HBECs). HE staining showed histopathological features in the lung tissue of RSV-infected mice. ELISA examined the contents of proinflammatory cytokines in RSV-infected mice. Western blotting evaluated the protein abundance of proinflammatory cytokines in RSV-infected HBECs and assessed NF-κB pathway-associated protein expression in RSV-infected mice and RSV-treated HBECs.

Results

POU2AF1 presented depletion in RSV-infected children, mice, and HBECs. RSV-infected triggered lung injury and inflammatory cell infiltration in the mouse lung tissue, while POU2AF1 overexpression rescued these changes. RSV-infected induced inflammatory impairment in HBECs, whereas POU2AF1 reversed this effect. POU2AF1 suppressed the upregulated NF-κB pathway-associated protein expression in mice and HBECs under RSV infection.

Conclusion

POU2AF1 exerts a protective impact on RSV-induced acute bronchiolitis in vitro and in vivo through the NF-κB pathway. Our research may provide a novel direction for better therapy of RSV-triggered acute bronchiolitis.

Machine learning clinical decision support systems for surveillance: a case study on pertussis and RSV in children

We tested the performance of a machine learning (ML) algorithm based on signs and symptoms for the diagnosis of RSV infection or pertussis in the first year of age to support clinical decisions and provide timely data for public health surveillance. We used data from a retrospective case series of children in the first year of life investigated for acute respiratory infections in the emergency room from 2015 to 2020. We collected data from PCR laboratory tests for confirming pertussis or RSV infection, clinical symptoms, and routine blood testing results, which were used for the algorithm development. We used a LightGBM model to develop 2 sets of models for predicting pertussis and RSV infection: for each type of infection, we developed one model trained with the combination of clinical symptoms and results from routine blood test (white blood cell count, lymphocyte fraction and C-reactive protein), and one with symptoms only. All analyses were performed using Python 3.7.4 with Shapley values (Shap values) visualization package for predictor visualization. The performance of the models was assessed through confusion matrices. The models were developed on a dataset of 599 children. The recall for the pertussis model combining symptoms and routine laboratory tests was 0.72, and 0.74 with clinical symptoms only. For RSV infection, recall was 0.68 with clinical symptoms and laboratory tests and 0.71 with clinical symptoms only. The F1 score for the pertussis model was 0.72 in both models, and, for RSV infection, it was 0.69 and 0.75. ML models can support the diagnosis and surveillance of infectious diseases such as pertussis or RSV infection in children based on common symptoms and laboratory tests. ML-based clinical decision support systems may be developed in the future in large networks to create accurate tools for clinical support and public health surveillance.

Worldwide research trends on bronchiolitis in pediatrics

BACKGROUND

The COVID-19 pandemic has led to a significant increase in cases of bronchiolitis among children. As a result, there has been a corresponding increase in the number of publications on this topic. It is essential to examine the main areas of focus within the scientific literature to understand the current trends in research on pediatric bronchiolitis. This research aims to analyze the types of scientific advances related to pediatric bronchiolitis, the research trends being pursued, and the countries and research institutions leading these efforts. By understanding these aspects of bronchiolitis research, we can better understand the current state of knowledge and identify areas where further research is needed.

METHODS

To conduct a bibliometric analysis of the scientific literature on pediatric bronchiolitis, all relevant publications were retrieved from the Scopus database. The Scopus API and the SW VosViewer software with optimized modularity functions were used. This analysis was intended to provide a comprehensive overview of the current state of research on this topic, including the types of scientific advances being developed, the research trends being pursued, and the countries and research institutions leading these efforts.

RESULTS

A total of 3810 publications were reviewed. We observed an increasing number of publications, particularly in recent years. Of these, 73.7% were articles, 95% were written in English, and 29.4% were from the United States. The main keywords used in these publications included: human, bronchiolitis, child, preschool, preschool child, major clinical study, controlled study, pneumonia, asthma, adolescent, hospitalization, infant, and newborn. These keywords were grouped into six clusters: outpatient management, long-term consequences, etiology, intensive care management, diagnostic methods, and the main cluster, which focused on hospital treatment and clinical studies.

CONCLUSIONS

The bibliometric analysis of bronchiolitis research in pediatrics reveals that there has been a significant increase in the number of publications on this topic, particularly in recent years. Most of these publications are articles written in English and published in the United States. The main keywords used in these studies relate to various aspects of bronchiolitis, including diagnosis, treatment, and long-term consequences. The results of this analysis suggest that bronchiolitis is a topic of significant interest and concern for researchers and practitioners in the field of pediatrics and that further research is needed to improve our understanding and management of this condition.

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.

Respiratory Syncytial Virus in Veneto Region: Analysis of Hospital Discharge Records from 2007 to 2021

Respiratory Syncytial Virus (RSV) is a known cause of acute lower respiratory infections in infants and young children. The present study aims to analyze the temporal trends and characteristics of hospitalization related to RSV in the Veneto region (Italy) in the period between 2007 and 2021. The analysis is performed on all the hospital discharge records (HDRs) of public and accredited private hospitals corresponding to hospitalizations occurring in the Veneto region (Italy). HDRs are considered if they included at least one of the following ICD9-CM codes: 079.6-Respiratory Syncytial Virus (RSV); 466.11-acute bronchiolitis due to RSV; and 480.1-pneumonia due to RSV. Total annual cases, sex, and age-specific rates and trends are evaluated. Overall, an increasing trend in the number of hospitalizations due to RSV was observed between 2007 and 2019, with a slight drop in RSV seasons 2013-2014 and 2014-2015. From March 2020 to September 2021, almost no hospitalization was registered, but in the last quarter of 2021, the number of hospitalizations reached its highest value in the series. Our data confirm the preponderance of RSV hospitalizations in infants and young children, the seasonality of RSV hospitalizations, and acute bronchiolitis as the most frequent diagnosis. Interestingly, the data also show the existence of a significant burden of disease and a non-negligible number of deaths also in older adults. The present study confirms RSV is associated with high rates of hospitalization in infants and sheds light on the burden in the 70+ age group in which a considerable number of deaths was observed, as well as the parallelism with other countries, which is consistent with a wide underdiagnoses issue.

Metatranscriptome Reveals Specific Immune and Microbial Signatures of Respiratory Syncytial Virus Infection in Children

Respiratory syncytial virus (RSV) is the most frequently detected respiratory virus in children with acute lower respiratory tract infection. Previous transcriptome studies have focused on systemic transcriptional profiles in blood and have not compared the expression of multiple viral transcriptomes. Here, we sought to compare transcriptome responses to infection with four common respiratory viruses for children (respiratory syncytial virus, adenovirus, influenza virus, and human metapneumovirus) in respiratory samples. Transcriptomic analysis showed that cilium organization and assembly were common pathways related to viral infection. Compared with other virus infections, collagen generation pathways were distinctively enriched in RSV infection. We identified two interferon-stimulated genes (ISGs), CXCL11 and IDO1, which were upregulated to a greater extent in the RSV group. In addition, a deconvolution algorithm was used to analyze the composition of immune cells in respiratory tract samples. The proportions of dendritic cells and neutrophils in the RSV group were significantly higher than those in the other virus groups. The RSV group exhibited a higher richness of Streptococcus than the other virus groups. The concordant and discordant responses mapped out here provide a window to explore the pathophysiology of the host response to RSV. Last, according to host-microbe network interference, RSV may disrupt respiratory microbial composition by changing the immune microenvironment. IMPORTANCE In the present study, we demonstrated the comparative results of host responses to infection between RSV and other three common respiratory viruses for children. The comparative transcriptomics study of respiratory samples sheds light on the significant roles that ciliary organization and assembly, extracellular matrix changes, and microbial interactions play in the pathogenesis of RSV infection. Additionally, it was demonstrated that the recruitment of neutrophils and dendritic cells (DCs) in the respiratory tract is more substantial in RSV infection than in other viral infections. Finally, we discovered that RSV infection dramatically increased the expression of two ISGs (CXCL11 and IDO1) and the abundance of Streptococcus.

IL-17A plays a critical role in RSV infection in children and mice

BACKGROUND

IL-17A is a pleiotropic cytokine and intimately associated with asthma, but its role in respiratory syncytial virus (RSV) infection is conflicting in the literature.

METHODS

Children hospitalized in the respiratory department with RSV infection during RSV pandemic season of 2018-2020 were included. Nasopharyngeal aspirates were collected for pathogen and cytokines determination. In the murine model, RSV intranasal administrations were performed in wild-type and IL-17A-/- mice. Leukocytes and cytokines in bronchoalveolar lavage fluid (BALF), lung histopathology, and airway hyperresponsiveness (AHR) were measured. RORγt mRNA and IL-23R mRNA were semi-quantified by qPCR.

RESULTS

IL-17A increased significantly in RSV-infected children and was positively associated with pneumonia severity. In the murine model, IL-17A significantly increased in BALF of mice with RSV infection. Airway inflammation, lung tissue damage and AHR were significantly alleviated in wild-type mice following IL-17A neutralization and in the IL-17A-/- mice. IL-17A decreased by removing CD4⁺ T cells but increased by depleting CD8⁺ T cells. IL-6, IL-21, RORγt mRNA and IL-23R mRNA dramatically increased in parallel with the rise of IL-17A.

CONCLUSIONS

IL-17A contributes to the airway dysfunctions induced by RSV in children and murine. CD3⁺CD4⁺T cells are its major cellular sources and the IL-6/IL-21-IL-23R-RORγt signaling pathway might participate in its regulation.

The efficacy and safety of nirsevimab for the prevention of RSV infection among infants: A systematic review and meta-analysis

Background

Respiratory syncytial virus (RSV) is a leading cause of morbidity and mortality among infants with a global incidence of 9.5% and a mortality rate of 2.2%. The management of RSV infection is mainly supportive and, aside from emerging monoclonal antibodies, there has been no benefit of most preventive measures. Recent evidence suggests the potential of nirsevimab in preventing RSV infection.

Objective

This study aims to determine the efficacy and safety of nirsevimab in preventing RSV infection among infants using a review of relevant clinical trials.

Methods

We performed a random-effects meta-analysis among infants comparing nirsevimab injection vs. placebo. MEDLINE, CENTRAL, Scopus, and ClinicalTrials.gov were searched for relevant trials from inception to June 2022. The selected studies were assessed for risk of bias using the Revised Cochrane Risk-of-Bias (RoB2) tool and for quality of evidence using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach.

Results

Two studies were included. Data analysis showed that among infants, nirsevimab given before the RSV season significantly reduced the risk of medically attended RSV-related infection (RR: 0.26; 95% CI: 0.18-0.38) and the risk of hospitalization due to RSV infection (RR: 0.24; 95% CI: 0.13-0.47). There was no difference in terms of adverse events leading to death (RR: 0.78, 95% CI: 0.20-2.98) and adverse events of special interest (RR: 0.92, 95% CI: 0.25-3.38).

Conclusions

The use of nirsevimab to prevent RSV infections and hospitalization shows its promising potential, but studies on its cost-effectiveness are lacking. We recommend that further studies be done to look into the applicability and cost-effectiveness of nirsevimab.

Preventing Respiratory Syncytial Virus in Children in France: A Narrative Review of the Importance of a Reinforced Partnership Between Parents, Healthcare Professionals, and Public Health Authorities

The highly contagious respiratory syncytial virus (RSV) is responsible for up to approximately 50,000 hospitalisations during each RSV season in children aged under 5 years in France, with the burden greatest in infants younger than 1 year who were born at term. There is a need for a strategy to universally protect young children from RSV infection, and thereby reduce the pressure that RSV places every year on RSV-infected children, their parents, and French healthcare systems. Potential strategies currently undergoing clinical investigation include passive immunisation via maternal vaccination or administration of long-acting monoclonal antibodies at or soon after birth, followed by vaccination later in infancy or childhood. An ongoing partnership and collaboration between parents, public health authorities, and frontline primary healthcare will need to be reinforced once these new RSV prevention strategies are available, to facilitate their use and ensure that all children receive adequate protection from the start of their first RSV season.

The mechanism and pharmacodynamics of 2-((1H-indol-3-yl)thio/sulfinyl)-N-pheny acetamide derivative as a novel inhibitor against human respiratory syncytial virus

Human respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection worldwide. Until now, there are no licenced vaccines or effective antiviral drugs against RSV infections. In our previous work, we found 2-((1H-indol-3-yl)thio/sulfinyl)-N-pheny acetamide derivatives (4-49 C and 1-HB-63) being a novel inhibitor against RSV in vitro. Here, we explored the underlying mechanism of 2-((1H-indol-3-yl)thio/sulfinyl)-N-pheny acetamide derivatives to inhibit RSV replication in vitro and disclosed that 4–49 C worked as the inhibitor of membrane fusion and 1-HB-63 functioned at the stage of RSV genome replication/transcription. Yet, both of them could not inhibit RSV infection of BALB/c mice by using RSV-Luc, in vivo imaging and RT-qPCR analyses, for which it may be due to the fast metabolism in vivo. Our work suggests that further structural modification and optimisation of 2-((1H-indol-3-yl) thio/sulfinyl)-N-pheny acetamide derivative are needed to obtain drug candidates with effective anti-RSV activities in vivo.

Human Respiratory Syncytial Virus Infections among Hospitalized Children in Poland during 2010-2020: Study Based on the National Hospital Registry

Background: Human respiratory syncytial virus (RSV) is responsible for infections mainly affecting the lower respiratory tract in infants and young children after the first exposure. The aim of the study is to show up-to-date information on RSV hospitalization cases in Poland in children aged < 5 years. Methods: A retrospective, population-based study was conducted using data from hospital discharge records of patients hospitalized from 2010−2020. Results: The study group consisted of 57,552 hospitalizations of RSV children. The mean and median ages were 232 (95% CI: 230−234) and 132 (IQR 63−271) days. The mean annual hospitalization rate for patients with RSV infection was estimated to be 267.5 per 100,000, and the highest was observed in children < 1 year (1132.1 per 100,000). The mean annual hospitalization rate was significantly higher in patients living in urban than rural regions (p < 0.001). A statistically significant increase in the number of hospitalizations was observed (p < 0.0001) during the analyzed period. The seasonal pattern was found with the highest rates of hospitalizations in the January−March period. Conclusions: The increasing RSV hospitalization rate requires further research and may be the basis for urgent healthcare measures. The results may be helpful in comparative analyses in the European and global context.

Impact of immunoprophylaxis with palivizumab on respiratory syncytial virus infection in preterm infants less than 35 weeks in Colombian hospitals

OBJECTIVE

To evaluate the impact of immunoprophylaxis with palivizumab in preterm infants less than 35 weeks in terms of hospitalization rate, intensive care unit requirement, and mortality.

METHODS

A prospective cohort study was conducted at six Colombian hospitals. Preterm infants less than 35 weeks who received at least one dose of palivizumab during the first 6 months of life were included. The primary outcome was the hospitalization rate related to respiratory syncytial virus (RSV) infection.

RESULTS

A total of 222 newborns participated in the study; 204 (91.8%) completed the 6-month follow-up, and three died during the study. 88.7% received a second dose of palivizumab, 79.7% a third, 34.7% a fourth, and 25.2% a fifth. The nonadjusted incidence rate of RSV infection was 2.4%, and the overall RSV-positive hospitalization rate was 1.9%. The proportion of patients that required Neonatal Intensive Care Unit (NICU) and mechanical ventilation in relation to RSV infection was 1.4%. Discharge with home oxygen, pulmonary dysplasia, and being younger than 6 months were significantly associated with respiratory infection. Furthermore, exposition to cigarette smoke was the only factor associated with increased risk of hospitalization. The group that required hospitalization received fewer doses of palivizumab (p = 0.049). No discontinuation of treatment due to adverse events were reported. No death was judged to be related to palivizumab.

CONCLUSION

The hospitalization rate and the need for NICU admission were lower than those reported in the literature. In this real-life setting, palivizumab appears to be effective in preventing serious cases of RSV infection.

Respiratory Syncytial Virus

Respiratory syncytial virus (RSV) is a ubiquitous virus and infects nearly every child before their second birthday. Causing a wide array of symptoms, ranging from a mild cold to respiratory failure and even death, it is an illness that every general pediatrician will encounter on a yearly basis. It is important to know which populations are at risk for severe disease and what we can do to protect them from RSV and treat them if they do contract it. Many preventive measures are being studied, but so far, RSV has proved a challenging virus to capture and control. As our technology and knowledge grow, there is hope for a vaccine, more attainable and longer-lasting immunoprophylaxis, and better treatment options for those who do contract the disease. [Pediatr Ann. 2022;51(10):e376-e378.].

Expected Impact of Universal Immunization With Nirsevimab Against RSV-Related Outcomes and Costs Among All US Infants in Their First RSV Season: A Static Model

BACKGROUND

Respiratory syncytial virus (RSV) is associated with substantial morbidity in the United States, especially among infants. Nirsevimab, an investigational long-acting monoclonal antibody, was evaluated as an immunoprophylactic strategy for infants in their first RSV season and for its potential impact on RSV-associated, medically attended lower respiratory tract illness (RSV-MALRTI) and associated costs.

METHODS

A static decision-analytic model of the US birth cohort during its first RSV season was developed to estimate nirsevimab's impact on RSV-related health events and costs; model inputs included US-specific costs and epidemiological data. Modelled RSV-related outcomes included primary care and emergency room visits, hospitalizations including intensive care unit admission and mechanical ventilations, and RSV-related mortality.

RESULTS

Under current standard of care, RSV caused 529 915 RSV-MALRTIs and 47 281 hospitalizations annually, representing $1.2 billion (2021 US dollars [USD]) in costs. Universal immunization of all infants with nirsevimab is expected to reduce 290 174 RSV-MALRTI, 24 986 hospitalizations, and expenditures of $612 million 2021 USD.

CONCLUSIONS

An all-infant immunization strategy with nirsevimab could substantially reduce the health and economic burden for US infants during their first RSV season. While this reduction is driven by term infants, all infants, including palivizumab-eligible and preterm infants, would benefit from this strategy.

Insights into the Anti-inflammatory and Antiviral Mechanisms of Resveratrol

Resveratrol is a naturally occurring stilbene phytoalexin phenolic compound, which has been extensively studied on its biological activity. It has been widely accepted that resveratrol possesses anti-inflammatory and antiviral activities. In this review, we summarize the anti-inflammatory dosages and mechanism and antiviral mechanism of resveratrol. Since viral infections are often accompanied by inflammation, we propose that the NF-κB signaling pathway is a key and common molecular mechanism of resveratrol to exert anti-inflammatory and antiviral effects. For future studies, we believe that resveratrol's anti-inflammatory and antiviral mechanisms can consider the upstream signaling molecules of the NF-κB signaling pathway. For resveratrol antivirus, future studies can be conducted on the interaction of resveratrol with key proteins or important enzymes of the virus. In addition, we also think that the clinical application of resveratrol is very important. In short, resveratrol is a promising anti-inflammatory and antiviral drug, and research on it needs to be expanded.

Out-of-Season Epidemic of Respiratory Syncytial Virus during the COVID-19 Pandemic: The High Burden of Child Hospitalization in an Academic Hospital in Southern Italy in 2021

Respiratory syncytial virus (RSV) infection is the most common cause of hospitalization in young children. In the last 2 years, public health measures aimed at controlling the spread of SARS-CoV-2 have affected the epidemiology and seasonality of RSV worldwide. The aim of this descriptive retrospective observational study was to describe the characteristics of children hospitalized with RSV in an academic tertiary care hospital in Southern Italy in 2021. We also investigate the seasonal trends of RSV from 2017 to 2021. The demographic characteristics, comorbidities, clinical data, and coinfections were retrospectively evaluated. Compared with previous seasons, the 2021 outbreak of RSV was characterized by an increased number of patients, with a delayed peak observed in November. Overall, 179 children, including 128 (71.5%) aged <12 months, were hospitalized for RSV infection between August and December 2021. Ten children (5.6%) were admitted to the intensive care unit (ICU), all aged <5 months. One patient (0.5%) aged <1 month with severe comorbidities died. The severity of symptoms was significantly associated with younger age, underlying chronic disease, and the length of hospital stay (p < 0.05 each). History of prematurity was not significantly associated with the presence of coinfections. Because of the high burden of RSV infection and the expected larger RSV epidemics resulting from a greater number of RSV-naïve children, systematic epidemiological and virological surveillance is needed. Appropriate pathways for access to RSV prevention in all infants should also be introduced.

Respiratory Syncytial Virus Nonstructural Protein 1 Promotes 5-Lipoxygenase via miR-19a-3p

Background

Respiratory syncytial virus (RSV) infection can regulate the expression of a wide range of noncoding microRNAs (miRNAs), in which mir-19a-3p can participate in airway inflammatory response by regulating 5-lipoxygenase (5-LO) pathway. RSV nonstructural protein (NS) 1 is involved in the airway hyperresponsiveness during RSV infection.

Methods

The expression levels of miR-19a-3p and inflammatory signaling-related indicators were detected using quantitative real-time PCR and western blot analyses on the A549 cells transfected with NS1 expression plasmids (pNS1). The 5-LO-mediated inflammatory signaling pathway was assessed when the miR-19a-3p or 5-LO was inhibited.

Results

The immunofluorescence analysis showed that the plasmid-mediated NS1 protein was observed in both the cytoplasm and nucleus. The expression level of miR-19a-3p was significantly upregulated in the pNS1 or RSV-treated cells, which was reversed by the NS1 small interfering RNA. In addition, pNS1 also upregulated the expression of 5-LO, interleukin-5 (IL-5), and leukotriene B4 (LTB4), which was also significantly inhibited by the miR-19a-3p antagonists. The 5-LO inhibitor MK886 prevented the increase in the expression level of IL-5 induced by pNS1.

Conclusions

These results suggested that the RSV NS1 might play an important role in the pathogenesis of RSV by activating the 5-LO and subsequent inflammatory cytokines through miR-19a-3p.

RSV Prevention in All Infants: Which Is the Most Preferable Strategy?

Respiratory syncytial virus (RSV) causes a spectrum of respiratory illnesses in infants and young children that may lead to hospitalizations and a substantial number of outpatient visits, which result in a huge economic and healthcare burden. Most hospitalizations happen in otherwise healthy infants, highlighting the need to protect all infants against RSV. Moreover, there is evidence on the association between early-life RSV respiratory illness and recurrent wheezing/asthma-like symptoms As such, RSV is considered a global health priority. However, despite this, the only prevention strategy currently available is palivizumab, a monoclonal antibody (mAb) indicated in a subset of preterm infants or those with comorbidities, hence leaving the majority of the infant population unprotected against this virus. Therefore, development of prevention strategies against RSV for all infants entering their first RSV season constitutes a large unmet medical need. The aim of this review is to explore different immunization approaches to protect all infants against RSV. Prevention strategies include maternal immunization, immunization of infants with vaccines, immunization of infants with licensed mAbs (palivizumab), and immunization of infants with long-acting mAbs (e.g., nirsevimab, MK-1654). Of these, palivizumab use is restricted to a small population of infants and does not offer a solution for all-infant protection, whereas vaccine development in infants has encountered various challenges, including the immaturity of the infant immune system, highlighting that future pediatric vaccines will most likely be used in older infants (>6 months of age) and children. Consequently, maternal immunization and immunization of infants with long-acting mAbs represent the two feasible strategies for protection of all infants against RSV. Here, we present considerations regarding these two strategies covering key areas which include mechanism of action, "consistency" of protection, RSV variability, duration of protection, flexibility and optimal timing of immunization, benefit for the mother, programmatic implementation, and acceptance of each strategy by key stakeholders. We conclude that, based on current data, immunization of infants with long-acting mAbs might represent the most effective approach for protecting all infants entering their first RSV season.

Integrated Trinity Test With RPA-CRISPR/Cas12a-Fluorescence for Real-Time Detection of Respiratory Syncytial Virus A or B

Respiratory syncytial virus (RSV) is a common virus that causes respiratory infection, especially severe respiratory infection in infants and young children, the elderly people over 65 years old, and people with weak immunity. Currently, RSV infection has no effective vaccine and antiviral treatment. The number of deaths due to RSV infection increases every year. Moreover, RSV A infection occurs in a large number and has severe clinical symptoms and complications than RSV B infection. Therefore, the development of a simple, rapid, and inexpensive detection method with high amplification efficiency, high sensitivity, and specificity is very important for the diagnosis of RSV A or RSV B infection, which can help in the early clinical medication and prevent the progress of the disease. Therefore, we developed an integrated trinity test with an RPA-CRISPR/Cas12a-fluorescence (termed IT-RAISE) assay system to detect RSV A or RSV B. The characteristic of the IT-RAISE system is that after target recognition, the reporter single-stranded DNA (ssDNA) is cleaved by Cas12a that is activated by different crRNAs to detect the generated fluorescent signal. This method is simple and helps in adding all reagents rapidly. It is a high-sensitive method that can detect 1.38 × 10¹ copies/μl of the target sequences, and it can distinguish RSV A or RSV B infection within 37 min. In addition, clinical specimens were detected for IT-RAISE system. It was found that the sensitivity and specificity of RSV A were 73.08 and 90%, respectively, and those of RSV B were 42.86 and 93.33%, respectively. The cost of ONE specimen for IT-RAISE system was approximately $ 2.6 (excluding rapid RNA extraction and reverse transcription costs). IT-RAISE system has good clinical application prospects for detecting RSV A or RSV B infection; it is a simple, rapid, and inexpensive method with high amplification efficiency, high sensitivity, and high specificity. The IT-RAISE system might also detect other viral or bacterial infections.

Favipiravir Inhibits Hepatitis A Virus Infection in Human Hepatocytes

Hepatitis A virus (HAV) is a causative agent of acute hepatitis and can occasionally induce acute liver failure. However, specific potent anti-HAV drug is not available on the market currently. Thus, we investigated several novel therapeutic drugs through a drug repositioning approach, targeting ribonucleic acid (RNA)-dependent RNA polymerase and RNA-dependent deoxyribonucleic acid polymerase. In the present study, we examined the anti-HAV activity of 18 drugs by measuring the HAV subgenomic replicon and HAV HA11-1299 genotype IIIA replication in human hepatoma cell lines, using a reporter assay and real-time reverse transcription polymerase chain reaction, respectively. Mutagenesis of the HAV 5’ untranslated region was also examined by next-generation sequencing. These specific parameters were explored because lethal mutagenesis has emerged as a novel potential therapeutic approach to treat RNA virus infections. Favipiravir inhibited HAV replication in both Huh7 and PLC/PRF/5 cells, although ribavirin inhibited HAV replication in only Huh7 cells. Next-generation sequencing demonstrated that favipiravir could introduce nucleotide mutations into the HAV genome more than ribavirin. In conclusion, favipiravir could introduce nucleotide mutations into the HAV genome and work as an antiviral against HAV infection. Provided that further in vivo experiments confirm its efficacy, favipiravir would be useful for the treatment of severe HAV infection.

Synergism and Antagonism of Bacterial-Viral Coinfection in the Upper Respiratory Tract

Streptococcus pneumoniae (the pneumococcus) is a leading cause of pneumonia in children under 5 years of age. Coinfection by pneumococci and respiratory viruses enhances disease severity. Little is known about pneumococcal coinfections with respiratory syncytial virus (RSV). Here, we developed a novel infant mouse model of coinfection using pneumonia virus of mice (PVM), a murine analogue of RSV, to examine the dynamics of coinfection in the upper respiratory tract, an anatomical niche that is essential for host-to-host transmission and progression to disease. Coinfection increased damage to the nasal tissue and increased production of the chemokine CCL3. Nasopharyngeal pneumococcal density and shedding in nasal secretions were increased by coinfection. In contrast, coinfection reduced PVM loads in the nasopharynx, an effect that was independent of pneumococcal strain and the order of infection. We showed that this "antagonistic" effect was absent using either ethanol-killed pneumococci or a pneumococcal mutant deficient in capsule production and incapable of nasopharyngeal carriage. Colonization with a pneumococcal strain naturally unable to produce capsule also reduced viral loads. The pneumococcus-mediated reduction in PVM loads was caused by accelerated viral clearance from the nasopharynx. Although these synergistic and antagonistic effects occurred with both wild-type pneumococcal strains used in this study, the magnitude of the effects was strain dependent. Lastly, we showed that pneumococci can also antagonize influenza virus. Taken together, our study has uncovered multiple novel facets of bacterial-viral coinfection. Our findings have important public health implications, including for bacterial and viral vaccination strategies in young children. IMPORTANCE Respiratory bacterial-viral coinfections (such as pneumococci and influenza virus) are often synergistic, resulting in enhanced disease severity. Although colonization of the nasopharynx is the precursor to disease and transmission, little is known about bacterial-viral interactions that occur within this niche. In this study, we developed a novel mouse model to examine pneumococcal-viral interactions in the nasopharynx with pneumonia virus of mice (PVM) and influenza. We found that PVM infection benefits pneumococci by increasing their numbers in the nasopharynx and shedding of these bacteria in respiratory secretions. In contrast, we discovered that pneumococci decrease PVM numbers by accelerating viral clearance. We also report a similar effect of pneumococci on influenza. By showing that coinfections lead to both synergistic and antagonistic outcomes, our findings challenge the existing dogma in the field. Our work has important applications and implications for bacterial and viral vaccines that target these microbes.

Favipiravir in the Battle with Respiratory Viruses

Abstract:

Among antiviral drugs, the vast majority targets only one or two related viruses. The conventional model, one virus - one drug, significantly limits therapeutic options. Therefore, in the strategy of controlling viral infections, there is a necessity to develop compounds with pleiotropic effects. Favipiravir (FPV) emerged as a strong candidate to become such a drug. The aim of the study is to present up-to-date information on the role of favipiravir in the treatment of viral respiratory infections. The anti-influenza activity of favipiravir has been confirmed in cell culture experiments, animal models and clinical trials. Thoroughly different - from the previously registered drugs - mechanism of action suggests that FVP can be used as a countermeasure for the novel or re-emerging influenza virus infections. In recent months, favipiravir has been broadly investigated due to its potential efficacy in the treatment of Covid-19. Based on preclinical and clinical studies and a recently published meta-analysis it seems that favipiravir may be a promising antiviral drug in the treatment of patients with Covid-19. FPV is also effective against other RNA respiratory viruses and may be a candidate for the treatment of serious infections caused by human rhinovirus, respiratory syncytial virus, metapneumovirus, parainfluenza viruses and hantavirus pulmonary syndrome.

Ephedrae Herba and Cinnamomi Cortex interactions with G glycoprotein inhibit respiratory syncytial virus infectivity

Although respiratory syncytial virus (RSV) is a major cause of respiratory tract infection in children, no effective therapies are available. Recently, RSV G, the attachment glycoprotein, has become a major focus in the development of therapeutic strategies against RSV infection. Treatment of RSV-infected cultured cells with maoto, a traditional herbal medicine for acute febrile diseases, significantly reduced the viral RNA and titers. RSV attachment to the cell surface was inhibited both in the presence of maoto and when RSV particles were pre-treated with maoto. We demonstrated that maoto components, Ephedrae Herba (EH) and Cinnamomi Cortex (CC), specifically interacted with the central conserved domain (CCD) of G protein, and also found that this interaction blocked viral attachment to the cellular receptor CX3CR1. Genetic mutation of CX3C motif on the CCD, the epitope for CX3CR1, decreased the binding capacity to EH and CC, suggesting that CX3C motif was the target for EH and CC. Finally, oral administration of maoto for five days to RSV-infected mice significantly reduced the lung viral titers. These experiments clearly showed the anti-RSV activity of EH and CC mixed in maoto. Taken together, this study provides insights for the rational design of therapies against RSV infection.

Potential Neurocognitive Symptoms Due to Respiratory Syncytial Virus Infection

Respiratory infections are among the major public health burdens, especially during winter. Along these lines, the human respiratory syncytial virus (hRSV) is the principal viral agent causing acute lower respiratory tract infections leading to hospitalization. The pulmonary manifestations due to hRSV infection are bronchiolitis and pneumonia, where the population most affected are infants and the elderly. However, recent evidence suggests that hRSV infection can impact the mother and fetus during pregnancy. Studies have indicated that hRSV can infect different cell types from the placenta and even cross the placenta barrier and infect the fetus. In addition, it is known that infections during the gestational period can lead to severe consequences for the development of the fetus due not only to a direct viral infection but also because of maternal immune activation (MIA). Furthermore, it has been described that the development of the central nervous system (CNS) of the fetus can be affected by the inflammatory environment of the uterus caused by viral infections. Increasing evidence supports the notion that hRSV could invade the CNS and infect nervous cells, such as microglia, neurons, and astrocytes, promoting neuroinflammation. Moreover, it has been described that the hRSV infection can provoke neurological manifestations, including cognitive impairment and behavioral alterations. Here, we will review the potential effect of hRSV in brain development and the potential long-term neurological sequelae.

Respiratory Syncytial Virus Phosphoprotein Residue S156 Plays a Role in Regulating Genome Transcription and Replication

Respiratory syncytial virus (RSV) is a single-stranded, negative-sense RNA virus in the family Pneumoviridae and genus Orthopneumovirus that can cause severe disease in infants, immunocompromised adults, and the elderly. The RSV viral RNA-dependent RNA polymerase (vRdRp) complex is composed of the phosphoprotein (P) and the large polymerase protein (L). The P protein is constitutively phosphorylated by host kinases and has 41 serine (S) and threonine (T) residues as potential phosphorylation sites. To identify important phosphorylation residues in the P protein, we systematically and individually mutated all S and T residues to alanine (A) and analyzed their effects on genome transcription and replication by using a minigenome system. We found that the mutation of eight residues resulted in minigenome activity significantly lower than that of wild-type (WT) P. We then incorporated these mutations (T210A, S203A, T151A, S156A, T160A, S23A, T188A, and T105A) into full-length genome cDNA to rescue recombinant RSV. We were able to recover four recombinant viruses (with T151A, S156A, T160A, or S23A), suggesting that RSV-P residues T210, S203, T188, and T105 are essential for viral RNA replication. Among the four recombinant viruses rescued, rRSV-T160A caused a minor growth defect relative to its parental virus while rRSV-S156A had severely restricted replication due to decreased levels of genomic RNA. During infection, P-S156A phosphorylation was decreased, and when passaged, the S156A virus acquired a known compensatory mutation in L (L795I) that enhanced both WT-P and P-S156A minigenome activity and was able to partially rescue the S156A viral growth defect. This work demonstrates that residues T210, S203, T188, and T105 are critical for RSV replication and that S156 plays a critical role in viral RNA synthesis. IMPORTANCE RSV-P is a heavily phosphorylated protein that is required for RSV replication. In this study, we identified several residues, including P-S156, as phosphorylation sites that play critical roles in efficient viral growth and genome replication. Future studies to identify the specific kinase(s) that phosphorylates these residues can lead to kinase inhibitors and antiviral drugs for this important human pathogen.

Endothelial Dysfunction through Oxidatively Generated Epigenetic Mark in Respiratory Viral Infections

The bronchial vascular endothelial network plays important roles in pulmonary pathology during respiratory viral infections, including respiratory syncytial virus (RSV), influenza A(H1N1) and importantly SARS-Cov-2. All of these infections can be severe and even lethal in patients with underlying risk factors.A major obstacle in disease prevention is the lack of appropriate efficacious vaccine(s) due to continuous changes in the encoding capacity of the viral genome, exuberant responsiveness of the host immune system and lack of effective antiviral drugs. Current management of these severe respiratory viral infections is limited to supportive clinical care. The primary cause of morbidity and mortality is respiratory failure, partially due to endothelial pulmonary complications, including edema. The latter is induced by the loss of alveolar epithelium integrity and by pathological changes in the endothelial vascular network that regulates blood flow, blood fluidity, exchange of fluids, electrolytes, various macromolecules and responses to signals triggered by oxygenation, and controls trafficking of leukocyte immune cells. This overview outlines the latest understanding of the implications of pulmonary vascular endothelium involvement in respiratory distress syndrome secondary to viral infections. In addition, the roles of infection-induced cytokines, growth factors, and epigenetic reprogramming in endothelial permeability, as well as emerging treatment options to decrease disease burden, are discussed.

Clinico-virological Profile, Intensive Care Needs, and Outcome of Infants with Acute Viral Bronchiolitis: A Prospective Observational Study

OBJECTIVES

The objective of the study was to describe the clinico-virological profile, treatment details, intensive care needs, and outcome of infants with acute viral bronchiolitis (AVB).

METHODOLOGY

In this prospective observational study, 173 infants with AVB admitted to the pediatric emergency room and pediatric intensive care unit (PICU) of a tertiary care teaching hospital in North India during November 2019 to February 2020 were enrolled. The data collection included clinical features, viruses detected [respiratory syncytial virus (RSV), rhinovirus, influenza A virus, parainfluenza virus (PIV) 2 and 3, and human metapneumovirus (hMPV)], complications, intensive care needs, treatment, and outcomes. Multivariate analysis was performed to determine independent predictors for PICU admission.

RESULTS

Most common symptoms were rapid breathing (98.8%), cough (98.3%), and fever (74%). On examination, tachypnea (98.8%), chest retractions (93.6%), respiratory failure (84.4%), wheezing (49.7%), and crepitations (23.1%) were observed. RSV and rhinovirus were the predominant isolates. Complications were noted in 25% of cases as encephalopathy (17.3%), transaminitis (14.3%), shock (13.9%), acute kidney injury (AKI) (7.5%), myocarditis (6.4%), multiple organ dysfunction syndrome (MODS) (5.8%), and acute respiratory distress syndrome (ARDS) (4.6%). More than one-third of cases required PICU admission. The treatment details included nasal cannula oxygen (11%), continuous positive airway pressure (51.4%), high-flow nasal cannula (14.5%), mechanical ventilation (23.1%), nebulization (74%), antibiotics (35.9%), and vasoactive drugs (13.9%). The mortality was 8.1%. Underlying comorbidity, chest retractions, respiratory failure at admission, presence of shock, and need for mechanical ventilation were independent predictors of PICU admission. Isolation of virus or coinfection was not associated with disease severity, intensive care needs, and outcomes.

CONCLUSION

Among infants with AVB, RSV and rhinovirus were predominant. One-third infants with AVB needed PICU admission. The presence of comorbidity, chest retractions, respiratory failure, shock, and need for mechanical ventilation independently predicted PICU admission.

HOW TO CITE THIS ARTICLE

Angurana SK, Takia L, Sarkar S, Jangra I, Bora I, Ratho RK, et al. Clinico-virological Profile, Intensive Care Needs, and Outcome of Infants with Acute Viral Bronchiolitis: A Prospective Observational Study. Indian J Crit Care Med 2021;25(11):1301-1307.

Contribution of Nanotechnologies to Vaccine Development and Drug Delivery against Respiratory Viruses

According to the Center for Disease Control and Prevention (CDC), the coronavirus disease 2019, a respiratory viral illness linked to significant morbidity, mortality, production loss, and severe economic depression, was the third-largest cause of death in 2020. Respiratory viruses such as influenza, respiratory syncytial virus, SARS-CoV-2, and adenovirus, are among the most common causes of respiratory illness in humans, spreading as pandemics or epidemics throughout all continents. Nanotechnologies are particles in the nanometer range made from various compositions. They can be lipid-based, polymer-based, protein-based, or inorganic in nature, but they are all bioinspired and virus-like. In this review, we aimed to present a short review of the different nanoparticles currently studied, in particular those which led to publications in the field of respiratory viruses. We evaluated those which could be beneficial for respiratory disease-based viruses; those which already have contributed, such as lipid nanoparticles in the context of COVID-19; and those which will contribute in the future either as vaccines or antiviral drug delivery systems. We present a short assessment based on a critical selection of evidence indicating nanotechnology's promise in the prevention and treatment of respiratory infections.

Epidemiology and prevention of respiratory syncytial virus infections in children in Italy

Respiratory syncytial virus (RSV) is the leading global cause of respiratory infections in infants and the second most frequent cause of death during the first year of life. This highly contagious seasonal virus is responsible for approximately 3 million hospitalizations and 120,000 deaths annually among children under the age of 5 years. Bronchiolitis is the most common severe manifestation; however, RSV infections are associated with an increased long-term risk for recurring wheezing and the development of asthma. There is an unmet need for new agents and a universal strategy to prevent RSV infections starting at the time of birth. RSV is active between November and April in Italy, and prevention strategies must ensure that all neonates and infants under 1 year of age are protected during the endemic season, regardless of gestational age at birth and timing of birth relative to the epidemic season. Approaches under development include maternal vaccines to protect neonates during their first months, monoclonal antibodies to provide immediate protection lasting up to 5 months, and pediatric vaccines for longer-lasting protection. Meanwhile, improvements are needed in infection surveillance and reporting to improve case identification and better characterize seasonal trends in infections along the Italian peninsula. Rapid diagnostic tests and confirmatory laboratory testing should be used for the differential diagnosis of respiratory pathogens in children. Stakeholders and policymakers must develop access pathways once new agents are available to reduce the burden of infections and hospitalizations.

Burden of illness in infants and young children hospitalized for respiratory syncytial virus: A rapid review

Respiratory syncytial virus (RSV) infections are common among young children and represent a significant burden to patients, their families and the Canadian health system. Here we conduct a rapid review of the burden of RSV illness in children 24 months of age or younger. Four databases (Medline, Embase, Cochrane Database of Clinical Trials, ClinicalTrials.gov from 2014 to 2018), grey literature and reference lists were reviewed for studies on the following: children with or without a risk factor, without prophylaxis and with lab-confirmed RSV infection. Of 29 studies identified, 10 provided within-study comparisons and few examined clinical conditions besides prematurity. For infants of 33-36 weeks gestation (wGA) versus term infants, there was low-to-moderate certainty evidence for an increase in RSV-hospitalizations (n=599,535 infants; RR 2.05 [95% CI 1.89-2.22]; 1.3 more per 100 [1.1-1.5 more]) and hospital length of stay (n=7,597 infants; mean difference 1.00 day [95% CI 0.88-1.12]). There was low-to-moderate certainty evidence of little-to-no difference for infants born at 29-32 versus 33-36 wGA for hospitalization (n=12,812 infants; RR 1.20 [95% CI 0.92-1.56]). There was low certainty evidence of increased mechanical ventilation for hospitalized infants born at 29-32 versus 33-35 wGA (n=212 infants; RR 1.58, 95% CI 0.94-2.65). Among infants born at 32-35 wGA, hospitalization for RSV in infancy may be associated with increased wheeze and asthma-medication use across six-year follow-up (RR range 1.3-1.7). Children with versus without Down syndrome may have increased hospital length of stay (n=7,206 children; mean difference 3.00 days, 95% CI 1.95-4.05; low certainty). Evidence for other within-study comparisons was of very low certainty. In summary, prematurity is associated with greater risk for RSV-hospitalization and longer hospital length of stay, and Down syndrome may be associated with longer hospital stay for RSV. Respiratory syncytial virus-hospitalization in infancy may be associated with greater wheeze and asthma-medication use in early childhood. Lack of a comparison group was a major limitation for many studies.