The burden of respiratory syncytial virus in healthy term-born infants in Europe: a prospective birth cohort study

Parental knowledge on the respiratory syncytial virus before the nirsevimab immunization program: Attitudes toward immunization in an autonomous community of Spain

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in young children and associated with most bronchiolitis- and pneumonia-related hospitalizations. A new preventive monoclonal antibody (MAb), nirsevimab, has been launched in the United States, Luxembourg, and France, and was recently approved to be given in a population-based manner throughout Spain. This study aimed to have a first pre-immunization insight into the Spanish parental knowledge about bronchiolitis, RSV, and nirsevimab immunization. Parents in Murcia with children <2 years of age up to the date of September 1, 2023, were selected to complete a questionnaire. The primary endpoint was the parental knowledge about bronchiolitis, RSV, and nirsevimab. A total of 3,217 responses were analyzed. The majority (95.8%) were aware of bronchiolitis. Meanwhile, 46.6% of the respondents knew about RSV, most of them only after the first child's birth. Information about RSV or bronchiolitis was mainly obtained from family members, with only 4.8% reporting having been informed by Health care Professionals (HCPs). Only 11.2% of respondents were aware of nirsevimab. Nonetheless, these were not entirely satisfied with the information received (score of 3.3 out of 5) and shared that HCPs should be the primary source of information. The present survey then highlights the need for better and more efficient educational strategies directed to all parents/legal guardians. It also sheds some light on the different factors that should be considered to improve awareness of RSV immunization to decrease its burden in Spain and beyond.

Evolving Epidemiology of Pediatric Respiratory Syncytial Virus (RSV) Cases Around COVID-19 Pandemic: Impact and Clinical Insights, Retrospective Cohort Study

BACKGROUND

The burden of respiratory syncytial virus (RSV) in high-risk pediatric patients remains unclear. Therefore, this study aims to characterize pediatric RSV cases from January 2019 to December 2022 and assess the impact of the COVID-19 pandemic on RSV burden and RSV-related outcomes. In addition, examining factors influencing RSV-related hospitalization.

METHODS

This is a retrospective study that included pediatric patients (aged 14 and below) who presented at King Faisal Specialist Hospital and Research Centre (KFSHRC) in Riyadh, Saudi Arabia with RSV infection identified using real-time reverse-transcriptase polymerase chain reaction assays. Statistical analyses were performed using STATA.

RESULTS

A total of 885 RSV cases were reported; (56.05%) were males and (43.95%) were females with a median age of 24 months [interquartile range (IQR): 11-60]. 534 (60.34%) required hospitalization. As for RSV seasonality, there was a significant increase in RSV prevalence following the COVID-19 pandemic, escalating from 205 cases in 2019 to 425 cases in 2022. The increase in 2022 was evident in January and persisted from September to December, reaching its peak during the months of October (20.70% - 88 cases) and November (32.00% - 136 cases). About (27.12%) of RSV infected children were medically free patients. Symptomatic patients exhibited various clinical manifestations, with ventilation necessary in (13.11%) of cases. Further analysis revealed significant changes in RSV-related outcomes post-COVID-19, including a decrease in hospitalization rates, an increase in medically free patients, and a lower need for ventilation (p < 0.05). Notably, a significant proportion of RSV admissions occurred within the first 6 months of life, with (77.69%) in the age group of 0 to 5 months. In addition, previous RSV infection, prematurity, low birth weight, renal disease, congenital heart disease, endocrine/metabolic disease, neuro/neuromuscular diseases, and genetic disorders were positively associated with hospitalization (P < 0.05). Interestingly, asthma and bone marrow transplantation were negatively associated with hospitalization (P < 0.05). The mortality rate in this study is (2.37%) (21/885).

CONCLUSION

This study provides a comprehensive understanding of the demographic and clinical factors influencing RSV outcomes, highlighting the impact of the COVID-19 pandemic and shedding light on potential risk factors for RSV-related hospitalization. The highest prevalence of RSV during (September to January), aligning with global patterns and emphasizing the importance of timing in preventive strategies.

Respiratory viral infections before the COVID-19 in Portugal: A single center study

Objectives

We aimed to describe the respiratory viruses (RV) found in respiratory samples from patients admitted to Hospital de São Bernardo, Setúbal, Portugal, between October 2019 and March 2020, and to correlate these with clinical features.

Design

This retrospective study explored 948 fresh frozen naso/oropharyngeal swabs, tested by reverse transcription-polymerase chain reaction.

Results

Rhinovirus/enterovirus, influenza, and respiratory syncytial virus (hRSV) were the most prevalent RV. Half of the patients fulfilled the acute respiratory infection (ARI) and/or influenza-like illness (ILI) criteria, with increasing age significantly reducing the risk of ARI and/or ILI. Hospital admission was more frequently observed in symptomatic patients, but the length of stay and mortality were significantly lower. Most (96.5 %) patients had a main respiratory diagnosis. In adults, the most prevalent was pneumonia, which particularly affected older patients, while in children, the most common was bronchiolitis. The number of hospital admissions was high. Sudden onset, shortness of breath, older age, and hRSV detection significantly increased the risk of hospital admission overall. In bronchiolitis, female gender significantly increased the risk of hospital admission, while older age significantly reduced this risk. Twenty patients died within the first month of sampling, and all were older adults. Older age and male gender significantly increased the risk of death.

Conclusions

Respiratory viral infections can have a significant clinical impact, particularly in young infants with bronchiolitis and older adults with pneumonia. This study provides the first snapshot of the respiratory viral infections just before the outbreak of SARS-CoV-2 in Portugal, providing relevant clinical insights.

The Multifaceted Burden of Respiratory Syncytial Virus (RSV) Infections in Young Children on the Family: A European Study

INTRODUCTION

Since the majority of hospitalisations due to RSV occur in young children, the illness profoundly influences the entire family. However, comprehensive evidence regarding its overall effects remains limited. The ResQ Family study aims to investigate the burden of RSV-induced pediatric hospitalisation on affected families.

METHODS

Spanning the 2022-2023 RSV season, an interdisciplinary, observational study was conducted in Germany, France, Italy and Sweden. Using an online questionnaire, parents and caregivers of children (< 24 months of age) with an RSV-induced hospitalisation were recruited. Information was gathered on topics related to RSV and parental health-related quality of life (HRQoL) during the acute infection phase (t0) and 6 weeks later (t1). Descriptive evaluations of the data set were performed during t0 and regarding a potential change over the observation period (t0 vs. t1). Subgroup analysis aimed to further identify differences across the countries.

RESULTS

A total set of 138 affected parents/caregivers were included in the study, with 59 participants responding to the follow-up survey (t1). Particularly during the acute infection phase, parental HRQoL was shown to be negatively influenced by the child's RSV infection [total score (p < 0.001, d = 0.54), parent HRQoL summary score (p < 0.001, d = 0.67) and family functioning summary score (p = 0.007, d = 0.33)]. Significant disparities in disease awareness and support structures were observed across Europe, with France and Sweden showing notably higher levels.

CONCLUSION

The ResQ Family study provides convincing evidence that RSV-associated hospitalisations in young children across Europe generate a multifaced burden for the entire family, partly even beyond the acute infection phase. Standardised approaches for disease prevention at societal, educational and policy levels are needed to guarantee every newborn the best possible start into life.

TRIAL REGISTRATION

ClinicalTrials.gov, identifier, NCT05550545.

Safety and Efficacy of Nirsevimab in a Universal Prevention Program of Respiratory Syncytial Virus Bronchiolitis in Newborns and Infants in the First Year of Life in the Valle d'Aosta Region, Italy, in the 2023-2024 Epidemic Season

Respiratory syncytial virus (RSV) bronchiolitis remains a significant global health burden, particularly in newborns and infants during their first year of life. The quest for an effective preventive strategy against RSV has long been sought, and recent developments have shown promise in the form of nirsevimab, a monoclonal antibody specifically designed for RSV prophylaxis. Valle d'Aosta was the first Italian region to propose universal prophylaxis with nirsevimab for newborns and infants in their first epidemic season as early as 2023-2024. This study describes the effectiveness and safety of the universal prevention program of RSV bronchiolitis using the monoclonal antibody nirsevimab in children resident in Valle d'Aosta born during the 2023-2024 epidemic season. There were 556 neonates born from 1 May 2023 to 15 February 2024. The risk of hospitalization for RSV bronchiolitis in 2023-2024 was 3.2%, compared to 7% in the 2022-2023 epidemic season (p < 0.001). After the start of the prophylaxis campaign with nirsevimab, the risk of hospitalization was 8.3% in the sample of infants who did not adhere to the prophylaxis, while no child in the sample of those treated (p < 0.001) was hospitalized for bronchiolitis. Few mild transient side effects were reported. This study shows the efficacy and safety of universal prophylaxis with nirsevimab in neonates, making Valle d'Aosta the first Italian region to offer universal prophylaxis to newborns without risk factors for RSV complications. Future research could further explore its long-term impact and cost-effectiveness.

Maternal Risk Factors for Respiratory Syncytial Virus Lower Respiratory Tract Infection in Otherwise Healthy Preterm and Term Infants: A Systematic Review and Meta-analysis

BACKGROUND/OBJECTIVE

To date, there is no published, formal assessment of all maternal risk factors for respiratory syncytial virus lower respiratory tract infection (RSV-LRTI) in infants. A systematic literature review and meta-analysis were undertaken to ascertain: What maternal risk factors are associated with an increased risk of RSV-LRTI in infants?

METHODS

The systematic literature review used explicit methods to identify, select and analyze relevant data. PubMed, Embase and the Cochrane Library were searched (November 2022) using terms regarding: (1) RSV/LRTI; (2) risk factors; (3) pregnant/postpartum population. Bayesian meta-analysis compared RSV hospitalization (RSVH) risk in infants born to mothers with or without certain risk factors.

RESULTS

A total of 2353 citations were assessed and 20 were included in the final review (10 individual studies; 10 pooled analyses). In 10 studies examining infants (<1 year) without comorbidities (primary outcome), 10 maternal risk factors were associated with RSV-LRTI/RSVH in multivariate analyses. Meta-analysis revealed smoking while pregnant increased infant RSVH risk by 2.01 (95% credible interval: 1.52-2.64) times, while breast-feeding was protective (0.73, 95% credible interval: 0.58-0.90). Risk scoring tools have reported that maternal risk factors contribute between 9% and 21% of an infant's total risk score for RSVH.

CONCLUSIONS

A greater understanding of maternal risk factors and their relative contribution to infant RSV-LRTI will enable more accurate assessments of the impact of preventive strategies.

RSV Severe Infection Risk Stratification in a French 5-Year Birth Cohort Using Machine-learning

BACKGROUND

Respiratory syncytial virus (RSV) poses a substantial threat to infants, often leading to challenges in hospital capacity. With recent pharmaceutical developments to be used during the prenatal and perinatal periods aimed at decreasing the RSV burden, there is a pressing need to identify infants at risk of severe disease. We aimed to stratify the risk of developing a clinically severe RSV infection in infants under 1 year of age.

METHODS

This retrospective observational study was conducted at the Hospices Civils de Lyon, France, involving infants born between 2014 and 2018. This study focused on infants hospitalized with severe and very severe acute lower respiratory tract infections associated with RSV (SARI-WI group). Data collection included perinatal information and clinical data, with machine-learning algorithms used to discriminate SARI-WI cases from nonhospitalized infants.

RESULTS

Of 42,069 infants, 555 developed SARI-WI. Infants born in November were very likely (>80%) predicted SARI-WI. Infants born in October were very likely predicted SARI-WI except for births at term by vaginal delivery and without siblings. Infants were very unlikely (<10%) predicted SARI-WI when all the following conditions were met: born in other months, at term, by vaginal delivery and without siblings. Other infants were possibly (10-30%) or probably (30-80%) predicted SARI-WI.

CONCLUSIONS

Although RSV preventive measures are vital for all infants, and specific recommendations exist for patients with high-risk comorbidities, in situations where prioritization becomes necessary, infants born just before or within the early weeks of the epidemic should be considered as a risk group.

Estimated Impact of Nirsevimab on the Incidence of Respiratory Syncytial Virus Infections Requiring Hospital Admission in Children < 1 Year, Weeks 40, 2023, to 8, 2024, Spain

BACKGROUND

Data from the sentinel surveillance system of severe acute respiratory infections in Spain were used to estimate the impact of administration of nirsevimab to children born from 1 April 2023 onwards.

METHODS

Estimated RSV hospitalisations in < 1-year-olds during weeks 40, 2023, to 8, 2024, were compared to the number that would be expected after accounting for the background change in RSV circulation in the 2023/24 season, compared to 2022/23.

RESULTS

We estimated 9364-9875 RSV hospitalisations less than expected, corresponding to a 74%-75% reduction.

Effectiveness and impact of universal prophylaxis with nirsevimab in infants against hospitalisation for respiratory syncytial virus in Galicia, Spain: initial results of a population-based longitudinal study

BACKGROUND

Galicia (Spain) was one of the first regions worldwide to incorporate nirsevimab for universal respiratory syncytial virus (RSV) prophylaxis in infants into its immunisation programme. The NIRSE-GAL longitudinal population-based study aimed to assess nirsevimab effectiveness in preventing hospitalisations (ie, admittance to hospital).

METHODS

The 2023-24 immunisation campaign with nirsevimab in Galicia began on Sept 25, 2023, and concluded on March 31, 2024. The campaign targeted three groups: infants born during the campaign (seasonal group), infants younger than 6 months at the start of the campaign (catch-up group), and infants aged 6-24 months with high-risk factors at the start of the campaign (high-risk group). Infants in the seasonal group were offered immunisation on the first day of life before discharge from hospital. Infants in the catch-up and high-risk groups received electronic appointments to attend a public hospital or health-care centre for nirsevimab administration. For this interim analysis, we used data collected from Sept 25 to Dec 31, 2023, from children born up to Dec 15, 2023. Data were retrieved from public health registries. Nirsevimab effectiveness in preventing RSV-associated lower respiratory tract infection (LRTI) hospitalisations; severe RSV-related LRTI requiring intensive care unit admission, mechanical ventilation, or oxygen support; all-cause LRTI hospitalisations; and all-cause hospitalisations was estimated using adjusted Poisson regression models. Data from five past RSV seasons (2016-17, 2017-18, 2018-19, 2019-20, and 2022-23), excluding the COVID-19 pandemic period, were used to estimate the number of RSV-related LRTI hospitalisations averted along with its IQR. The number needed to immunise to avoid one case in the 2023-24 season was then estimated from the averted cases. Nirsevimab safety was routinely monitored. The NIRSE-GAL study protocol was registered on ClinicalTrials.gov (NCT06180993), and follow-up of participants is ongoing.

FINDINGS

9408 (91·7%) of 10 259 eligible infants in the seasonal and catch-up groups received nirsevimab, including 6220 (89·9%) of 6919 in the seasonal group and 3188 (95·4%) of 3340 in the catch-up group. 360 in the high-risk group were offered nirsevimab, 348 (97%) of whom received it. Only infants in the seasonal and catch-up groups were included in analyses to estimate nirsevimab effectiveness and impact because there were too few events in the high-risk group. In the catch-up and seasonal groups combined, 30 (0·3%) of 9408 infants who received nirsevimab and 16 (1·9%) of 851 who did not receive nirsevimab were hospitalised for RSV-related LRTI, corresponding to an effectiveness of 82·0% (95% CI 65·6-90·2). Effectiveness was 86·9% (69·1-94·2) against severe RSV-related LRTI requiring oxygen support, 69·2% (55·9-78·0) against all-cause LRTI hospitalisations, and 66·2% (56·0-73·7) against all-cause hospitalisations. Nirsevimab effectiveness against other endpoints of severe RSV-related LRTI could not be estimated because of too few events. RSV-related LRTI hospitalisations were reduced by 89·8% (IQR 87·5-90·3), and the number needed to immunise to avoid one RSV-related LRTI hospitalisation was 25 (IQR 24-32). No severe adverse events related to nirsevimab were registered.

INTERPRETATION

Nirsevimab substantially reduced infant hospitalisations for RSV-associated LRTI, severe RSV-associated LRTI requiring oxygen, and all-cause LRTI when given in real-world conditions. These findings offer policy makers and health authorities robust, real-world, population-based evidence to guide the development of strategies for RSV prevention.

FUNDING

Sanofi and AstraZeneca.

TRANSLATION

For the Spanish translation of the abstract see Supplementary Materials section.

Effectiveness of Nirsevimab Immunoprophylaxis Administered at Birth to Prevent Infant Hospitalisation for Respiratory Syncytial Virus Infection: A Population-Based Cohort Study

Respiratory syncytial virus (RSV) infection is a frequent cause of hospitalisation in the first few months of life; however, this risk rapidly decreases with age. Nirsevimab immunoprophylaxis was approved in the European Union for the prevention of RSV-associated lower respiratory tract disease in infants during their first RSV season. We evaluated the effectiveness of nirsevimab in preventing hospitalisations for confirmed RSV infection and the impact of a strategy of immunisation at birth. A population-based cohort study was performed in Navarre, Spain, where nirsevimab was offered at birth to all children born from October to December 2023. Cox regression was used to estimate the hazard ratio of hospitalisation for PCR-confirmed RSV infection between infants who received and did not receive nirsevimab. Of 1177 infants studied, 1083 (92.0%) received nirsevimab. The risk of hospitalisation for RSV was 8.5% (8/94) among non-immunised infants versus 0.7% (8/1083) in those that were immunised. The estimated effectiveness of nirsevimab was 88.7% (95% confidence interval, 69.6-95.8). Immunisation at birth of infants born between October and December 2023 prevented one hospitalisation for every 15.3 immunised infants. Immunisation of children born from September to January might prevent 77.5% of preventable hospitalisations for RSV in infants born in 2023-2024. These results support the recommendation of nirsevimab immunisation at birth to children born during the RSV epidemic or in the months immediately before to prevent severe RSV infections and alleviate the overload of paediatric hospital resources.

Respiratory syncytial virus: A new era

Respiratory syncytial virus (RSV) is a major public health problem that has undergone significant changes in recent years. First of all, it has become easier to diagnose with highly reliable and rapidly available confirmatory tests. This has led to a better understanding of its epidemiology and RSV has gone from being a disease of the pediatric age group, severe only in infants and immunosuppressed children, to being a common disease in people of all ages, particularly important in patients of advanced age or with immunosuppressive diseases. Recent therapeutic and prophylactic advances, both with long-lasting monoclonal antibodies and vaccines, are another reason for satisfaction. For these reasons, the COVID and Emerging Pathogens Committee of the Illustrious Official College of Physicians of Madrid (ICOMEM) has considered it pertinent to review this subject in the light of new knowledge and new resources for dealing with this infection. We have formulated a series of questions that we believe will be of interest not only to members of the College but also to any non-expert in this subject, with a particular focus on the situation of RSV infection in Spain.

Vaccination in pregnancy. Consensus document of the CAV-AEP and the SEGO

During pregnancy, physiological changes in the immune response make pregnant women more susceptible to serious infection, increasing the risk for the mother as well as the foetus, newborn and infant. All women should be correctly and fully vaccinated as they enter their reproductive years, especially against diseases such as tetanus, hepatitis B, measles, rubella and varicella. In addition to the recommended vaccines, in risk situations, inactivated vaccines could be administered to women who were not correctly vaccinated before, while attenuated vaccines are contraindicated. Despite the fact that vaccination during pregnancy is a very important preventive measure and the existing recommendations from public health authorities, scientific societies and health professionals, the vaccination coverage could clearly be improved, especially against influenza and SARS-CoV-2, so any health professional involved in the care of pregnant women should proactively recommend these vaccines. The Spanish Association of Pediatrics (AEP), through its Advisory Committee on Vaccines, and the Spanish Society of Gynaecology and Obstetrics (SEGO) recommend vaccination against the following diseases during pregnancy: against influenza and COVID-19, in any trimester of pregnancy and during the postpartum period (up to 6 months post birth) in women not vaccinated during pregnancy; against pertussis, with the Tdap vaccine, between weeks 27 and 36 of gestation (in the CAV-AEP recommendations, preferably between weeks 27 and 28); and against RSV, with RSVPreF, between weeks 24 and 36 of gestation, preferably between weeks 32 and 36.

Molecular Epidemiology and Clinical Characteristics of an Outbreak on Respiratory Virus Coinfection in Gansu, China

This study aims to analyze the epidemiological and pathogenic characteristics of an outbreak primarily caused by respiratory syncytial virus (RSV), human rhinovirus (HRV), and human metapneumovirus (HMPV) in a kindergarten and primary school. The outbreak was investigated by field epidemiological investigation, and the common respiratory pathogens were screened by RT-PCR detection technology. The attack rate of this outbreak was 63.95% (110/172). Main symptoms included cough (85.45%), sore throat (60.91%), and sneezing (60.00%). Multifactorial logistic regression analysis revealed that continuous handwashing and mouth and nose covering when sneezing were protective factors. All 15 collected throat swab specimens tested positive for viruses, with HMPV as the predominant pathogen (80.00%), followed by HRV (53.33%), and two cases of positive respiratory syncytial virus (13.33%). Among them, six samples showed coinfections of HMPV and HRV, and one had coinfections of HMPV and RSV, resulting in a coinfection rate of 46.67%. Genetic sequencing indicated that the HMPV genotype in this outbreak was A2c, and the HRV genotype was type A, resulting in a coinfection outbreak of HMPV, HRV, and RSV in schools and kindergartens, suggesting that multi-pathogen surveillance of respiratory tract infections should be strengthened.

Clinical and economic burden of respiratory syncytial virus in children aged 0-5 years in Italy

BACKGROUND

Respiratory syncytial virus (RSV) is among the leading causes of hospitalization due to lower respiratory tract infections (LRTIs) in children younger than 5 years worldwide and the second cause of infant death after malaria. RSV infection occurs in almost all the infants before the second year of life with variable clinical severity, often requiring medical assistance. This analysis investigated patients aged 0-5 years with RSV infection focusing on epidemiology, clinical features, and economic burden of RSV-associated hospitalizations in a setting of Italian real clinical practice.

METHODS

An observational retrospective analysis was conducted on administrative databases of healthcare entities covering around 2.6 million residents of whom 120,000 health-assisted infants aged < 5 years. From 2010 to 2018, pediatric patients were included in the presence of hospitalization discharge diagnosis for RSV infections, and RSV-related acute bronchiolitis or pneumonia. Epidemiology, demographics, clinical picture and costs were evaluated in RSV-infected patients, overall and stratified by age ranges (0-1, 1-2, 2-5 years) and compared with an age-matched general population.

RESULTS

Overall 1378 RSV-infected children aged 0-5 years were included. Among them, the annual incidence rate of RSV-related hospitalizations was 175-195/100,000 people, with a peak in neonates aged < 1 year (689-806/100,000). While nearly 85% of infected infants were healthy, the remaining 15% presented previous hospitalization for known RSV risk factors, like preterm birth, or congenital heart, lung, and immune diseases. The economic analysis revealed that direct healthcare costs per patient/year were markedly higher in RSV patients than in the general population (3605€ vs 344€).

CONCLUSIONS

These findings derived from the real clinical practice in Italy confirmed that RSV has an important epidemiological, clinical, and economic burden among children aged 0-5 years. While the complex management of at-risk infants was confirmed, our data also highlighted the significant impact of RSV infection in infants born at term or otherwise healthy, demonstrating that all infants need protection against RSV disease, reducing then the risk of medium and long-term complications, such as wheezing and asthma.

A Genome-Wide Association Study of Respiratory Syncytial Virus Infection Severity in Infants

BACKGROUND

Respiratory syncytial virus (RSV) is a significant cause of infant morbidity and mortality worldwide. Most children experience at least one 1 RSV infection by the age of two 2 years, but not all develop severe disease. However, the understanding of genetic risk factors for severe RSV is incomplete. Consequently, we conducted a genome-wide association study of RSV severity.

METHODS

Disease severity was assessed by the ReSVinet scale, in a cohort of 251 infants aged 1 week to 1 year. Genotyping data were collected from multiple European study sites as part of the RESCEU Consortium. Linear regression models were used to assess the impact of genotype on RSV severity and gene expression as measured by microarray.

RESULTS

While no SNPs reached the genome-wide statistical significance threshold (P < 5 × 10-8), we identified 816 candidate SNPs with a P-value of <1 × 10-4. Functional annotation of candidate SNPs highlighted genes relevant to neutrophil trafficking and cytoskeletal functions, including LSP1 and RAB27A. Moreover, SNPs within the RAB27A locus significantly altered gene expression (false discovery rate, FDR P < .05).

CONCLUSIONS

These findings may provide insights into genetic mechanisms driving severe RSV infection, offering biologically relevant information for future investigations.

Respiratory Syncytial Virus-Associated Hospitalizations in Children: A 10-Year Population-Based Analysis in Finland, 2008-2018

BACKGROUND

The risk of respiratory syncytial virus (RSV) hospitalization is highest during the first months of life, but few studies have assessed the population-based rates of hospitalization in monthly age groups of infants.

METHODS

We determined the average population-based rates of hospitalization with virologically confirmed RSV infections in children ≤15 years of age admitted during the 10-year period of 2008-2018. Testing for RSV was routine in all children hospitalized with respiratory infections, and all RSV-positive children admitted at any time during the study period were included in the analyses.

RESULTS

The annual population-based rate of RSV hospitalization was highest in infants 1 month of age (52.0 per 1000 children; 95% CI, 45.2-59.7), followed by infants <1 month of age (34.8 per 1000; 95% CI, 29.2-41.1) and those 2 months of age (32.2 per 1000; 95% CI, 26.9-38.4). In cumulative age groups, the rate of hospitalization was 39.7 per 1000 (95% CI, 36.2-43.4) among infants <3 months of age, 26.8 per 1000 (95% CI, 24.8-29.0) in infants aged <6 months, and 15.8 per 1000 (95% CI, 14.7-17.0) in those <12 months of age.

CONCLUSION

In monthly age groups of infants, the incidence rates of virologically confirmed RSV hospitalization in all infants up to 3 months of age were substantially higher than those reported in earlier studies. These data may be important for improving the estimates of the cost-effectiveness of various interventions to reduce the burden of RSV in young infants.

Critical care of severe bronchiolitis during shortage of ICU resources

Large seasonal outbreaks of bronchiolitis put pressure on healthcare systems and particularly on intensive care units (ICUs). ICU admission is necessary to provide respiratory support to the severest cases, otherwise bronchiolitis can result in substantial mortality. ICU resources are often insufficient and there is scant evidence to guide the ICU clinical management. Most available studies do not cover the ICU-admitted cases and do not consider the associated public health issues. We review this topic through a multidisciplinary approach from both the clinical and public health perspectives, with an analysis based on pathophysiology and cost-effectiveness. We suggest ways to optimise respiratory care, minimise ICU stay, "protect" ICU beds and, whenever possible, make them available for other critically ill children. We also provide guidance on how to prepare ICUs to work under stressful conditions due to outbreaks and to reduce the risk of nosocomial cross-contamination, particularly in ICUs caring for high-risk children.

Funding

None.

Estimated Respiratory Syncytial Virus-Related Hospitalizations and Deaths Among Children and Adults in Spain, 2016-2019

INTRODUCTION

Respiratory syncytial virus (RSV) causes a substantial disease burden among infants. In older children and adults, incidence is underestimated due to nonspecific symptoms and limited standard-of-care testing. We aimed to estimate RSV-attributable hospitalizations and deaths in Spain during 2016-2019.

METHODS

Nationally representative hospitalization and mortality databases were obtained from the Ministry of Health and the National Statistical Office. A quasi-Poisson regression model was fitted to estimate the number of hospitalizations and deaths attributable to RSV as a function of periodic and aperiodic time trends and viral activity, while allowing for potential overdispersion.

RESULTS

In children, the RSV-attributable respiratory hospitalization incidence was highest among infants aged 0-5 months (3998-5453 cases/100,000 person-years, representing 72% of all respiratory hospitalizations) and decreased with age. In 2019, estimated rates in children 0-5, 6-11, 12-23 months and 6-17 years were approximately 1.3, 1.4, 1.5, and 6.5 times higher than those based on standard-of-care RSV-specific codes. In adults, the RSV-attributable cardiorespiratory hospitalization rate increased with age and was highest among persons ≥ 80 years (1325-1506 cases/100,000, 6.5% of all cardiorespiratory hospitalizations). In 2019, for persons aged 18-49, 50-59, 60-79, and ≥ 80 years, estimated rates were approximately 8, 6, 8, and 16 times higher than those based on standard-of-care RSV-specific codes. The RSV-attributable cardiorespiratory mortality rate was highest among ≥ 80 age group (126-150 deaths/100,000, 3.5-4.1% of all cardiorespiratory deaths), when reported mortality rate ranged between 0 and 0.5/100,000.

CONCLUSIONS

When accounting for under-ascertainment, estimated RSV-attributable hospitalizations were higher than those reported based on standard-of-care RSV-specific codes in all age groups but particularly among older children and older adults. Like other respiratory viruses, RSV contributes to both respiratory and cardiovascular complications. Efficacious RSV vaccines could have a high public health impact in these age and risk groups.

Preventative therapies for respiratory Syncytial virus (RSV) in children: Where are we now?

Respiratory Syncytial Virus (RSV) is a leading cause of hospitalization in young children and represents a substantial health-care burden around the world. Advances in research have helped identify the prefusion F protein as the key target component in RSV immunization. In this article, we review the previous, current, and ongoing research efforts for immunization against RSV in children. We present the different types of immunization which include monoclonal antibodies, maternal immunization and vaccines while addressing the challenges of preventing RSV infections in the pediatric population.

Substantial Burden of Nonmedically Attended RSV Infection in Healthy-Term Infants: An International Prospective Birth Cohort Study

BACKGROUND

During the first year of life, 1 in 4 infants develops a symptomatic respiratory syncytial virus (RSV) infection, yet only half seek medical attention. The current focus on medically attended RSV therefore underrepresents the true societal burden of RSV. We assessed the burden of nonmedically attended RSV infections and compared with medically attended RSV.

METHODS

We performed active RSV surveillance until the age of 1 year in a cohort (n = 993) nested within the Respiratory Syncytial Virus Consortium in EUrope (RESCEU) prospective birth cohort study enrolling healthy term-born infants in 5 European countries. Symptoms, medication use, wheezing, and impact on family life were analyzed.

RESULTS

For 97 of 120 (80.1%) nonmedically attended RSV episodes, sufficient data were available for analysis. In 50.5% (49/97), symptoms lasted ≥15 days. Parents reported impairment in usual daily activities in 59.8% (58/97) of episodes; worries, 75.3% (73/97); anxiety, 34.0% (33/97); and work absenteeism, 10.8% (10/93). Compared with medically attended RSV (n = 102, 9 hospital admissions), Respiratory Syncytial Virus NETwork (ReSViNET) severity scores were lower (3.5 vs 4.6, P < .001), whereas duration of respiratory symptoms and was comparable.

CONCLUSIONS

Even when medical attendance is not required, RSV infection poses a substantial burden to infants, families, and society. These findings are important for policy makers when considering the implementation of RSV immunization. Clinical Trials Registration. ClinicalTrials.gov (NCT03627572).

Resveratrol inhibits respiratory syncytial virus replication by targeting heparan sulfate proteoglycans

Resveratrol, renowned as an antioxidant, also exhibits significant potential in combatting severe respiratory infections, particularly the respiratory syncytial virus (RSV). Nevertheless, the specific mechanism underlying its inhibition of RSV replication remains unexplored. Heparan sulfate proteoglycans (HSPGs) play a pivotal role as attachment factors for numerous viruses, offering a promising avenue for countering viral infections. Our research has unveiled that resveratrol effectively curbs RSV infection in a dose-dependent manner. Remarkably, resveratrol disrupts the early stages of RSV infection by engaging with HSPGs, rather than interacting with RSV surface proteins like fusion (F) protein and glycoprotein (G). Resveratrol's affinity appears to be predominantly directed towards the negatively charged sites on HSPGs, thus impeding the binding of viral receptors. In an in vivo study involving RSV-infected mice, resveratrol demonstrates its potential by ameliorating pulmonary pathology. This improvement is attributed to the inhibition of pro-inflammatory cytokine expression and a reduction in viral load within the lungs. Notably, resveratrol specifically alleviates inflammation characterized by an abundance of neutrophils in RSV-infected mice. In summation, our data first shows how resveratrol combats RSV infection through interactions with HSPGs, positioning it as a promising candidate for innovative drug development targeting RSV infections. Our study provides insight into the mechanism of resveratrol antiviral infection.

Early estimates of nirsevimab immunoprophylaxis effectiveness against hospital admission for respiratory syncytial virus lower respiratory tract infections in infants, Spain, October 2023 to January 2024

The monoclonal antibody nirsevimab was at least 70% effective in preventing hospitalisations in infants with lower respiratory tract infections (LRTI) positive for respiratory syncytial virus (RSV) in Spain (Oct 2023-Jan 2024), where a universal immunisation programme began late September (coverage range: 79-99%). High protection was confirmed by two methodological designs (screening and test-negative) in a multicentre active surveillance in nine hospitals in three regions. No protection against RSV-negative LRTI-hospitalisations was shown. These interim results could guide public-health decision-making.

Safety and Immunogenicity of a ChAd155-Vectored Respiratory Syncytial Virus Vaccine in Infants 6-7 Months of age: A Phase 1/2 Randomized Trial

BACKGROUND

Respiratory syncytial virus (RSV) is a common cause of lower respiratory tract infections in infants. This phase 1/2, observer-blind, randomized, controlled study assessed the safety and immunogenicity of an investigational chimpanzee-derived adenoviral vector RSV vaccine (ChAd155-RSV, expressing RSV F, N, and M2-1) in infants.

METHODS

Healthy 6- to 7-month-olds were 1:1:1-randomized to receive 1 low ChAd155-RSV dose (1.5 × 1010 viral particles) followed by placebo (RSV_1D); 2 high ChAd155-RSV doses (5 × 1010 viral particles) (RSV_2D); or active comparator vaccines/placebo (comparator) on days 1 and 31. Follow-up lasted approximately 2 years.

RESULTS

Two hundred one infants were vaccinated (RSV_1D: 65; RSV_2D: 71; comparator: 65); 159 were RSV-seronaive at baseline. Most solicited and unsolicited adverse events after ChAd155-RSV occurred at similar or lower rates than after active comparators. In infants who developed RSV infection, there was no evidence of vaccine-associated enhanced respiratory disease (VAERD). RSV-A neutralizing titers and RSV F-binding antibody concentrations were higher post-ChAd155-RSV than postcomparator at days 31, 61, and end of RSV season 1 (mean follow-up, 7 months). High-dose ChAd155-RSV induced stronger responses than low-dose, with further increases post-dose 2.

CONCLUSIONS

ChAd155-RSV administered to 6- to 7-month-olds had a reactogenicity/safety profile like other childhood vaccines, showed no evidence of VAERD, and induced a humoral immune response. Clinical Trials Registration. NCT03636906.

Modeling the optimal seasonal monoclonal antibody administration strategy for respiratory syncytial virus (RSV) prevention based on age-season specific hospitalization rate of RSV in Suzhou, China, 2016-2022

BACKGROUND

The approval of nirsevimab brings light to reducing the heavy disease burden caused by respiratory syncytial virus (RSV). Considering the seasonality of RSV, the timing of administrating monoclonal antibody (mAb) is critical to maximize health utility. This study aimed to model and seek the optimal seasonal mAb administration strategy for preventing RSV-associated hospitalization.

METHODS

Age-season specific hospitalization rates for RSV-associated acute lower respiratory infection (RSV-ALRI) were estimated from a hospital-based birth cohort. Using these rates, we simulated and evaluated the effect of diverse mAb administration strategies on preventing RSV-ALRI hospitalization. Optimal strategies were selected based on their effectiveness and relative cost-effectiveness.

RESULTS

Compared with the year-round strategy of administration mAb at birth for all children, 291 out of the 854 candidate strategies, featuring diverse administration timing and age thresholds, demonstrated a greater number of averted RSV-ALRI hospitalizations and a lower number needed to treat (NNT). The NNT represents the number of mAb doses needed to prevent one case of RSV-ALRI hospitalization. Among the 291 strategies, administration mAb to children born in July-January or August-January at birth and administrating to the remaining <12 months old children in September, exhibited the highest increase in averted RSV-ALRI hospitalizations than the year-round strategy, with a magnitude of 23 %, while also achieve an 18 % reduction in NNT.

CONCLUSION

Administrating monoclonal antibodies to children born in July to January at birth, and administrating to the remaining <1-year-old children in September or October would be the optimal seasonal mAb administration strategy for children in Suzhou, China.

Epidemiology of Bronchiolitis and Respiratory Syncytial Virus and Analysis of Length of Stay from 2015 to 2022: Retrospective Observational Study of Hospital Discharge Records from an Italian Southern Province before and during the COVID-19 Pandemic

BACKGROUND

Severe respiratory infections, including pneumonia or bronchiolitis, caused by RSV can range from mild upper respiratory tract infections to those leading to hospitalization and serious complications such as respiratory failure in children. High-risk groups, such as premature infants and infants with underlying medical conditions, have a higher susceptibility to severe RSV disease. We conducted a retrospective study from years 2015 to 2022 in the Local Health Authority (LHA) of Pescara that counts about 320,000 inhabitants, with the aim to evaluate the burden of RSV infection, focusing on the incidence, hospitalization, and characteristics that may prolong hospital stays.

METHODS

All hospitalizations from 2015 to 2022 were extracted from the hospital discharge record. The monthly hospitalization rates were calculated and standardized by gender and age for the population resident in the Province of Pescara on 1 January 2015.

RESULTS

During the study period, 31,837 admissions were reported among patients aged less than 6 years. Of those, 520 hospitalizations were referred for bronchiolitis. Monthly admission rates highlighted the seasonality of bronchiolitis admissions, with higher rates in the months from December to March in all study years included. The winter seasons of years 2021 and 2022 reported a surge in bronchiolitis incidence, with a rate of 4.0/1000 (95% CI 2.964-5.146) in December 2021 and 4.0 (95% CI 2.891-5.020) in December 2022.

CONCLUSIONS

Bronchiolitis represents an important cause of hospitalization among patients aged less than 6 years. The incidence was particularly increased during the winter seasons in years 2021 and 2022.

Burden of respiratory syncytial virus disease across the lifespan in Australia and New Zealand: a scoping review

OBJECTIVES

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infection in young children worldwide. RSV is increasingly associated with severe respiratory disease in people aged >65 years. The heterogeneous landscape of RSV in Australia and New Zealand makes generalisation of results from global studies to local contexts difficult. Given the changing landscape of RSV, we aimed to examine the existing literature on the burden of RSV disease and identify evidence gaps in Australia and New Zealand.

STUDY DESIGN

Scoping review.

METHODS

We designed a scoping review protocol and searched the Web of Science and Scopus databases for eligible peer-reviewed publications. Data from eligible studies were charted and summarised in tabular and narrative form.

RESULTS

Of the 153 eligible publications identified, 123 investigated RSV disease in a hospital setting and six in primary care. Only six studies reported the economic burden of disease, all of which estimated direct healthcare costs associated with treatment and/or hospitalisation; no studies quantified the indirect costs or costs to families.

CONCLUSIONS

In this scoping review, we describe the effect of RSV disease in several high-risk populations, including children and adults. An improved understanding of the RSV burden of disease, both in primary care settings and economically, within the local context will assist with the implementation of preventative strategies, including vaccination programmes. Future studies to determine the true burden of RSV-associated morbidity, mortality and economic burden across the entire patient journey and among different healthcare settings will help prioritise emerging RSV therapeutics.

Burden of disease of respiratory syncytial virus in infants, young children and pregnant women and people

Background

Passive immunization products for infants and pregnant women and people have sparked interest in understanding Canada's respiratory syncytial virus (RSV) burden. This rapid review examines RSV burden of disease in infants, young children and pregnant women and people.

Methods

Electronic databases were searched to identify studies and systematic reviews reporting data on outpatient visits, hospitalizations, intensive care unit admissions, deaths and preterm labour associated with RSV. We also contacted Canadian respiratory virus surveillance experts for additional data.

Results

Overall, 17 studies on infants and young children and 10 studies on pregnant women and people were included, in addition to primary surveillance data from one Canadian territory (Yukon). There were higher rates of medical utilization for infants than older children. Hospitalization rates were highest in infants under six months (more than 1% annually), with 5% needing intensive care unit admission, but mortality was low. Severe outcomes often occurred in healthy full-term infants and burden was higher than influenza. Respiratory syncytial virus attack rate was 10%-13% among pregnant women and people. Only one study found a higher hospitalization rate in pregnant women and people compared to non-pregnant women and people. Limited evidence was found on intensive care unit admission, death and preterm birth for pregnant women and people.

Conclusion

While risk of severe outcomes is larger in high-risk infants and children, healthcare burden is greatest in healthy term infants. The RSV severity for pregnant women and people appears to be similar to that for non-pregnant women and people.

Outcomes of SARS-CoV-2 and Seasonal Viruses Among Children Hospitalized in Brazil

BACKGROUND AND OBJECTIVES

Understanding how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) interacts with other respiratory viruses is crucial for developing effective public health strategies in the postpandemic era. This study aimed to compare the outcomes of SARS-CoV-2 and seasonal viruses in children and adolescents hospitalized with severe acute respiratory infection (SARI).

METHODS

This population-based, retrospective cohort study included children and adolescents hospitalized with SARI from February 2020 to February 2023 in Brazil. The main exposure of interest was viral etiology. The primary outcome was in-hospital mortality. Competing risk analysis was used to account for time dependency and competing events.

RESULTS

A total of 235 829 patients had available results of the viral tests, with SARS-CoV-2 predominance. According to the competing-risk survival analysis, the estimated probability of a fatal outcome at 30 days of hospitalization according to the viral strain was 6.5%, 3.4%, 2.9%, 2.3%, 2.1%, and 1.8%, for SARS-CoV-2, coinfection, adenovirus, influenza, other viruses, and respiratory syncytial virus, respectively. Individuals with a positive test for SARS-CoV-2 had hazard of death 3 times higher than subjects with a negative test (hazard ratio, 3.3; 95% confidence interval, 3.1-3.5). After adjustment by the competing-risk multivariable analysis, admission in Northeast and North regions, oxygen saturation <95%, and the presence of comorbidities were risk factors for death in all viral strains.

CONCLUSIONS

SARS-CoV-2 infection had the highest hazard of in-hospital mortality in this pediatric cohort hospitalized with SARI. Regardless of viral etiology, the presence of underlying medical conditions was a risk factor for death.

Multicenter study to describe viral etiologies, clinical profiles, and outcomes of hospitalized children with severe acute respiratory infections, Egypt 2022

In late 2022, severe acute respiratory infections (SARI) surveillance reported an abrupt increase in non-COVID-19 infections among children after three years of drastic reductions. Signals of increased absenteeism due to respiratory symptoms among primary and preparatory school children were detected by Event-Based Surveillance. We conducted a hospital-based survey of children who were admitted with SARI to identify the causative pathogen(s) and estimate the burden of infection. A survey was conducted among children < 16 years in 21 referral hospitals in the three governorates with the highest SARI rates. Patients' demographics, clinical symptoms, and severity were collected from medical records using a line list. Patients were swabbed and tested for a panel of 33 respiratory pathogens by RT-PCR at the Central Laboratory in Cairo. Descriptive data analysis was performed for demographic data. Patients' characteristics were compared by causative agents' clinical picture and severity using Chi2 with a p < 0.05 significance. Overall, 317 patients were enrolled, 58.3% were ≤ 1 year of age, 61.5% were males. Of 229 (72.7%) of positively tested patients, viruses caused 92.1% including RSV 63.8%, Rhinovirus 10.0%, Influenza 9.2%, Adenovirus 5.2%, and 1.3% co-infected with two viruses. Bacteria caused 3.5% of cases and 4.4% had mixed viral-bacterial infections. Rhinovirus was the most common cause of death among children with SARI, followed by RSV (8.7% and 1.4%), whereas influenza and Adenovirus did not result in any deaths. Patients with viral-bacterial infections are more likely to be admitted to ICU and die at the hospital than bacterial or viral infections (60% and 20% vs. 31.8% and 1.9% vs. 12.5% and 12.5%, p < 0.001). Viruses particularly RSV are the leading cause of SARI causing significant health problem among children < 16 years in Egypt. Bacterial on top of viral infection can worsen disease courses and outcomes. Studies are required to estimate the SARI burden accurately among Egyptian children and a comprehensive approach tailored to Egypt is necessary to reduce its burden.

Effect of Palivizumab Prophylaxis on Respiratory Syncytial Virus Infection in Very Preterm Infants in the First Year of Life in The Netherlands

Respiratory Syncytial Virus (RSV) poses a severe threat to infants, particularly preterm infants. Palivizumab, the standard preventive prophylaxis, is primarily utilized in high-risk newborns due to its cost. This study assessed palivizumab's effectiveness in preventing RSV infections in predominantly very preterm infants during their first year of life. Serum samples from a prospective multicentre cohort study in the Netherlands were analyzed to assess RSV infection rates by measuring IgG levels against three RSV proteins: nucleoprotein, pre-fusion, and post-fusion protein. Infants were stratified based on gestational age (GA), distinguishing very preterm (≤32 weeks GA) from moderate/late preterm (>32 to ≤36 weeks GA). In very preterm infants, palivizumab prophylaxis significantly reduced infection rates (18.9% vs. 48.3% in the prophylaxis vs. non-prophylaxis group. Accounting for GA, sex, birth season, and birth weight, the prophylaxis group showed significantly lower infection odds. In infants with >32 to ≤36 weeks GA, the non-prophylaxis group (55.4%) showed infection rates similar to the non-prophylaxis ≤32-week GA group, despite higher maternal antibody levels in the moderate/late preterm infants. In conclusion, palivizumab prophylaxis significantly reduces RSV infection rates in very premature infants. Future research should explore clinical implications and reasons for non-compliance, and compare palivizumab with emerging prophylactics like nirsevimab aiming to optimize RSV prophylaxis and improve preterm infant outcomes.

Daily intranasal palivizumab to prevent respiratory syncytial virus infection in healthy preterm infants: a phase 1/2b randomized placebo-controlled trial

Background

Mucosal administration of monoclonal antibodies (mAbs) against respiratory pathogens is a promising alternative for systemic administration because lower doses are required for protection. Clinical development of mucosal mAbs is a highly active field yet clinical proof-of-concept is lacking.

Methods

In this investigator-initiated, double-blind, randomized placebo-controlled trial, we evaluated intranasal palivizumab for the prevention of RSV infection in preterm infants (Dutch Trial Register NTR7378 and NTR7403). We randomized infants 1:1 to receive intranasal palivizumab (1 mg/mL) or placebo once daily during the RSV season. Any RSV infection was the primary outcome and RSV hospitalization was the key secondary outcome. The primary outcome was analyzed with a mixed effect logistic regression on the modified intention-to-treat population.

Findings

We recruited 268 infants between Jan 14, 2019 and Jan 28, 2021, after which the trial was stopped for futility following the planned interim analysis. Adverse events were similar in both groups (22/134 (16.4%) palivizumab arm versus 26/134 (19.4%) placebo arm). There were 6 dropouts and 168 infants were excluded from the efficacy analyses due to absent RSV circulation during the SARS-CoV-2 pandemic. Any RSV infection was similar in infants in both groups (18/47 (38.3%) palivizumab arm versus 11/47 (23.4%) placebo arm; aOR 2.2, 95% CI 0.7-6.5).

Interpretation

Daily intranasal palivizumab did not prevent RSV infection in late preterm infants. Our findings have important implications for the clinical development of mucosal mAbs, namely the necessity of timely interim analyses and further research to understand mucosal antibody half-life.

Funding

Funded by the Department of Pediatrics, University Medical Centre Utrecht, the Netherlands.

Early lessons from the implementation of universal respiratory syncytial virus prophylaxis in infants with long-acting monoclonal antibodies, Galicia, Spain, September and October 2023

A monoclonal antibody for universal respiratory syncytial virus prophylaxis in infants has recently been licensed. We share our experiences of integrating nirsevimab into the regional immunisation programme in Galicia, Spain. After a 3-week hospital-based immunisation campaign with flexible individualised appointments and educational activities, nirsevimab uptake was 97.5% in the high-risk group, 81.4% in the catch-up group and 92.6% in infants born during the campaign. This successful implementation strategy can serve as a model and may inform other countries' programmatic deliberations.

Respiratory syncytial virus: can we still believe that after pandemic bronchiolitis is not a critical issue for public health?

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection among infants and young children, resulting in annual epidemics worldwide. Since the beginning of the COVID-19 pandemic, non-pharmacological interventions were applied, interfering with the circulation of most respiratory viruses, including RSV. The aim of this study is to analyze the RSV infection trend among hospitalized infants during the actual epidemic season (2022-2023) in comparison with the last pre-pandemic season (2018-2019), in order to outline whether significant differences emerge due to COVID-19 pandemia. We retrospectively reviewed medical data on infants hospitalized at the Bambino Gesù Children's Hospital with diagnosis of bronchiolitis in the current epidemic season and in the last pre-pandemic season, 2018-2019. RSV remains the main etiological agent of bronchiolitis in terms of frequency and severity of infections in the ongoing epidemic season. The first RSV case of the 2022-2023 season was detected at week 42 vs week 47 in the 2018-2019 season. The length of epidemic season was of 17 weeks in 2022-2023 vs 18 weeks in 2018-2019. Comparing the two seasons, age at admission was significantly higher in the current season (median age 2022-2023 65 days vs median age 2018-2019 58 days), but the disease severity was similar.       Conclusions: The 2022-2023 bronchiolitis season in Italy started earlier than the usual pre-pandemic seasons but seasonality pattern may be going back to the pre-pandemic one. This season was not more severe than the previous ones. The impact of RSV disease on health care systems and costs remains a critical issue. What is Known: • RSV is one of the major leading causes of hospitalization among children aged less than 3 months. SarsCOV2 pandemic interfered with the seasonal circulation of most respiratory viruses, Including RSV. What is New: • The 2022-2023 bronchiolitis season in Italy started and peaked earlier than the usual pre-pandemic seasons but seasonality pattern may be realigning to the pre-pandemic one. The impact of RSV disease on health care systems and costs is concerning.

Burden of Respiratory Syncytial Virus in the European Union: estimation of RSV-associated hospitalizations in children under 5 years

BACKGROUND

No overall estimate of respiratory syncytial virus (RSV)-associated hospitalizations in children aged under 5 years has been published for the European Union (EU). We aimed to estimate the RSV hospitalization burden in children aged under 5 years in EU countries and Norway, by age group.

METHODS

We collated national RSV-associated hospitalization estimates calculated using linear regression models via the RESCEU project for Denmark, England, Finland, Norway, the Netherlands, and Scotland, 2006-2018. Additional estimates were obtained from a systematic review. Using multiple imputation and nearest neighbor matching methods, we estimated overall RSV-associated hospitalizations and rates in the EU.

RESULTS

Additional estimates for 2 countries (France and Spain) were found in the literature. In the EU, an average of 245 244 (95% confidence interval [CI], 224 688-265 799) yearly hospital admissions with a respiratory infection per year were associated with RSV in children aged under 5 years, with most cases occurring among children aged under 1 year (75%). Infants aged under 2 months represented the most affected group (71.6 per 1000 children; 95% CI, 66.6-76.6).

CONCLUSIONS

Our findings will help support decisions regarding prevention efforts and represent an important benchmark to understand changes in the RSV burden following the introduction of RSV immunization programs in Europe.

Respiratory syncytial virus infection and novel interventions

The large global burden of respiratory syncytial virus (RSV) respiratory tract infections in young children and older adults has gained increased recognition in recent years. Recent discoveries regarding the neutralization-specific viral epitopes of the pre-fusion RSV glycoprotein have led to a shift from empirical to structure-based design of RSV therapeutics, and controlled human infection model studies have provided early-stage proof of concept for novel RSV monoclonal antibodies, vaccines and antiviral drugs. The world's first vaccines and first monoclonal antibody to prevent RSV among older adults and all infants, respectively, have recently been approved. Large-scale introduction of RSV prophylactics emphasizes the need for active surveillance to understand the global impact of these interventions over time and to timely identify viral mutants that are able to escape novel prophylactics. In this Review, we provide an overview of RSV interventions in clinical development, highlighting global disease burden, seasonality, pathogenesis, and host and viral factors related to RSV immunity.

Risk factors for severe respiratory syncytial virus infection during the first year of life: development and validation of a clinical prediction model

BACKGROUND

Novel immunisation methods against respiratory syncytial virus (RSV) are emerging, but knowledge of risk factors for severe RSV disease is insufficient for optimal targeting of interventions against them. Our aims were to identify predictors for RSV hospital admission from registry-based data and to develop and validate a clinical prediction model to guide RSV immunoprophylaxis for infants younger than 1 year.

METHODS

In this model development and validation study, we studied all infants born in Finland between June 1, 1997, and May 31, 2020, and in Sweden between June 1, 2006, and May 31, 2020, along with the data for their parents and siblings. Infants were excluded if they died or were admitted to hospital for RSV within the first 7 days of life. The outcome was hospital admission due to RSV bronchiolitis during the first year of life. The Finnish study population was divided into a development dataset (born between June 1, 1997, and May 31, 2017) and a temporal hold-out validation dataset (born between June 1, 2017, and May 31, 2020). The development dataset was used for predictor discovery and selection in which we screened 1511 candidate predictors from the infants', parents', and siblings' data, and developed a logistic regression model with the 16 most important predictors. This model was then validated using the Finnish hold-out validation dataset and the Swedish dataset.

FINDINGS

In total, there were 1 124 561 infants in the Finnish development dataset, 130 352 infants in the Finnish hold-out validation dataset, and 1 459 472 infants in the Swedish dataset. In addition to known predictors such as severe congenital heart defects (adjusted odds ratio 2·89, 95% CI 2·28-3·65), we confirmed some less established predictors for RSV hospital admission, most notably oesophageal malformations (3·11, 1·86-5·19) and lower complexity congenital heart defects (1·43, 1·25-1·63). The prediction model's C-statistic was 0·766 (95% CI 0·742-0·789) in Finnish data and 0·737 (0·710-0·762) in Swedish validation data. The infants in the highest decile of predicted RSV hospital admission probability had 4·5 times higher observed risk compared with others. Calibration varied according to epidemic intensity. The model's performance was similar to a machine learning (XGboost) model using all 1511 candidate predictors (C-statistic in Finland 0·771, 95% CI 0·754-0·788). The prediction model showed clinical utility in decision curve analysis and in hypothetical number needed to treat calculations for immunisation, and its C-statistic was similar across different strata of parental income.

INTERPRETATION

The identified predictors and the prediction model can be used in guiding RSV immunoprophylaxis in infants, or as a basis for further immunoprophylaxis targeting tools.

FUNDING

Sigrid Jusélius Foundation, European Research Council, Pediatric Research Foundation, and Academy of Finland.

Pediatric RSV-Associated Hospitalizations Before and During the COVID-19 Pandemic

Importance

Respiratory syncytial virus (RSV) is a leading cause of pediatric hospitalizations.

Objective

To describe the epidemiology and burden of RSV-associated hospitalizations among children and adolescents in Canadian tertiary pediatric hospitals from 2017 to 2022, including changes during the COVID-19 pandemic.

Design, Setting, and Participants

This cross-sectional study was conducted during 5 RSV seasons (2017-2018 to 2021-2022) at 13 pediatric tertiary care centers from the Canadian Immunization Monitoring Program Active (IMPACT) program. Hospitalized children and adolescents aged 0 to 16 years with laboratory-confirmed RSV infection were included.

Main Outcomes and Measures

The proportion of all-cause admissions associated with RSV and counts and proportions of RSV hospitalizations with intensive care unit (ICU) admission, prolonged stay (≥7 days), and in-hospital mortality were calculated overall and by season, age group, and region. Seasonality was described using epidemic curves. RSV hospitalizations for 2021-2022 were compared with those in the prepandemic period of 2017-2018 through 2019-2020. Bonferroni corrections were applied to P values to adjust for multiple statistical comparisons.

Results

Among 11 014 RSV-associated hospitalizations in children and adolescents (6035 hospitalizations among male patients [54.8%]; 5488 hospitalizations among patients aged <6 months [49.8%]), 2594 hospitalizations (23.6%) had admission to the ICU, of which 1576 hospitalizations (60.8%) were among children aged less than 6 months. The median (IQR) hospital stay was 4 (2-6) days. The mean (SD) number of RSV-associated hospitalizations during prepandemic seasons was 2522 (88.8) hospitalizations. There were 58 hospitalizations reported in 2020-2021, followed by 3170 hospitalizations in 2021-2022. The proportion of all-cause hospitalizations associated with RSV increased from a mean of 3.2% (95% CI, 3.1%-3.3%) before the pandemic to 4.5% (95% CI, 4.3%-4.6%) in 2021-2022 (difference, 1.3 percentage points; 95% CI, 1.1-1.5 percentage points; corrected P < .001). A significant increase in RSV-associated hospitalizations was found in 2021-2022 for 3 provinces (difference range, 2.5 percentage points; 95% CI, 1.4-3.6 percentage points for Quebec to 2.9 percentage points; 95% CI, 1.4-3.5 percentage points for Alberta; all corrected P < .001). Age, sex, ICU admission, prolonged length of stay, and case fatality rate did not change in 2021-2022 compared with the prepandemic period. Interregional differences in RSV seasonality were accentuated in 2021-2022, with peaks for 1 province in October, 4 provinces in December, and 3 provinces in April, or May.

Conclusions and Relevance

This study found that the burden of RSV-associated hospitalizations in Canadian pediatric hospitals was substantial, particularly among infants aged less than 6 months, and RSV hospitalizations increased in 2021-2022 compared with the prepandemic period, while severity of illness remained similar. These findings suggest that RSV preventive strategies for infants aged less than 6 months would be associated with decreased RSV disease burden in children.

Nirsevimab for the prevention of respiratory syncytial virus disease in children. Statement of the Spanish Society of Paediatric Infectious Disease (SEIP)

INTRODUCTION

Nirsevimab, a monoclonal antibody for the prevention of disease caused by respiratory syncytial virus (RSV), has recently been approved for use in Europe and Spain.

OBJECTIVES

To provide recommendations for the administration of nirsevimab for prevention of RSV disease.

METHODS

The approach chosen to develop these recommendations involved a critical review of the literature and the use of the Delphi and GRADE methods. An expert group was formed. The group engaged in three rounds to define the questions, express support or opposition, grade recommendations and establish the agreement or disagreement with the conclusions.

RESULTS

In the general neonatal population, routine administration of nirsevimab is recommended to reduce the frequency of illness and hospitalisation for bronchiolitis and RSV lower respiratory tract infection. Nirsevimab is recommended for all infants born in high-incidence RSV season and infants aged less than 6 months at the season onset. In infants born preterm between 29 and 35 weeks of gestation, with haemodynamically significant heart disease or with chronic lung disease, routine administration of nirsevimab is recommended to reduce the incidence of disease and hospitalisation due to bronchiolitis and RSV lower respiratory tract infection. In patients in whom palivizumab is currently indicated, its substitution by nirsevimab is recommended to reduce the burden of bronchiolitis.

CONCLUSIONS

Routine administration of nirsevimab to all infants aged less than 6 months born during the RSV season or aged less than 6 months at the start of the winter season is recommended to reduce the burden of disease and the frequency of hospitalization due to bronchiolitis.

The Path Towards Effective Respiratory Syncytial Virus Immunization Policies: Recommended Actions

The respiratory syncytial virus (RSV) causes a substantial burden worldwide. After over six decades of research, there is finally a licensed immunization option that can protect the broad infant population, and other will follow soon. RSV immunization should be in place from season 2023/2024 onwards. Doing so requires thoughtful but swift steps. This paper reflects the view of four immunization experts on the efforts being made across the globe to accommodate the new immunization options and provides recommendations organized around five priorities: (I) documenting the burden of RSV in specific populations; (II) expanding RSV diagnostic capacity in clinical practice; (III) strengthening RSV surveillance; (IV) planning for the new preventive options; (V) achieving immunization targets. Overall, Spain has been a notable example of converting RSV prevention into a national desideratum and has pioneered the inclusion of RSV in some of the regional immunization calendars for infants facing their first RSV season.

Why has the epidemiology of RSV changed during the COVID-19 pandemic?

The coronavirus disease 2019 (COVID-19) pandemic has drastically perturbed the epidemiology of Respiratory Syncytial Virus (RSV) respiratory tract infections in children. The reasons for this are not clear. In this article, we review the current literature and critically discuss the different theories to explain why the epidemiology of RSV has changed during the COVID-19 pandemic. Proposed mechanisms include decreased viral immunity in vulnerable age groups caused by the prolonged lack of RSV circulation early in the pandemic, potential Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2)-induced immune dysregulation, viral interactions between SARS-CoV-2 and RSV, and modifications in health-seeking behaviors as well as heath systems factors. Research in viral genomics and phylogeny, and more robust immunology research is needed to guide RSV prevention and health care resource planning.