Respiratory Syncytial Virus In Infants Research Articles

Assessment of effectiveness and impact of universal prophylaxis with nirsevimab for prevention of hospitalizations due to respiratory syncytial virus in infants. The NIRSE-GAL study protocol

ABSTRACT Nirsevimab has been recently licensed for universal RSV prophylaxis in infants. NIRSE-GAL is a three-year population-based study initiated in Galicia in September 2023. It aims to evaluate nirsevimab effectiveness against RSV-related hospitalizations lower respiratory tract infections (LRTI), severe RSV, all-cause LRTI, and all-cause hospitalization. NIRSE-GAL also aims to estimate nirsevimab impact on primary healthcare use in the short and mid-term, children’s wheezing and asthma, and medical prescriptions for RSV. The immunization campaigns will be scheduled based on the expected start week for the RSV season and will last the whole season. Immunization will be offered to: i) infants born during the campaign (seasonal), ii) infants < 6 months at the start of the campaign (catch-up), and iii) infants with high-risk factors, aged 6–24 months at the start of the campaign (high-risk). The follow-up period will start: i) the immunization date for all immunized infants, ii) the start of the campaign, for the non-immunized catch-up or high-risk groups, or iii) the birthdate for the non-immunized seasonal group. Infants will be followed up until outcome occurrence, death, or end of study. Nirsevimab effectiveness will be estimated using Poisson and Cox regression models. Sensitivity and stratified analyses will be undertaken. The number of averted cases and the number needed to immunize will be estimated. Immunization failure and nirsevimab safety will be monitored. NIRSE-GAL was approved by the ethics committee of Galicia (CEIC 2023–377) and registered in ClinicalTrials.gov (ID: NCT06180993). Findings will be mainly shared via peer-reviewed publications and scientific conferences.

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

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

Respiratory syncytial virus vaccination during pregnancy for improving infant outcomes.

Respiratory syncytial virus vaccination during pregnancy for improving infant outcomes.

Geographic Progression of Infant Respiratory Syncytial Virus Associated Bronchiolitis Across the United States Before and Since the Onset of COVID-19: Results From Four Health Systems, 2015-2023.

Respiratory syncytial virus (RSV) is a substantial cause of infant morbidity and mortality due to seasonal peaks of bronchiolitis across the United States. Clinical and viral surveillance plays a pivotal role in helping hospital systems prepare for expected surges in RSV bronchiolitis. Existing surveillance efforts have shown a geographic pattern of RSV positivity across the United States, with cases typically starting in the southeast and spreading north and west. Public health measures implemented due to the COVID-19 pandemic disrupted viral transmission across the nation and altered the expected seasonality of RSV. The impact of these changes on the geographic progression of infant RSV bronchiolitis across the United States has not been described. Here, we used clinical and viral surveillance data from four health care systems located in different regions of the United States to describe the geographic progression of infant RSV bronchiolitis across the country from 2015 to 2023. Prior to widespread circulation of SARS-CoV-2, infant RSV bronchiolitis followed an established geographic pattern associated with seasonal epidemics originating in Florida and spreading north (North Carolina and New York) and later westward (Nevada). Although public health and social measures implemented during the COVID-19 pandemic disrupted the seasonality of RSV disease, infant RSV bronchiolitis epidemics progressed across the nation in a pattern identical to the prepandemic era. Our findings highlight the importance of ongoing clinical and viral surveillance to optimally track the onset of RSV epidemics and allow health care systems to prepare for expected RSV bronchiolitis surges.

Short- and mid-term morbidity and primary-care burden due to infant respiratory syncytial virus infection: A Spanish 6-year population-based longitudinal study.

The morbidity burden of respiratory syncytial virus (RSV) in infants extends beyond hospitalization. Defining the RSV burden before implementing prophylaxis programs is essential for evaluating any potential impact on short- to mid-term morbidity and the utilization of primary healthcare (PHC) and emergency services (ES). We established this reference data using a population-based cohort approach. Infants hospitalized for RSV from January 2016 to March 2023 were matched with non-hospitalized ones based on birthdate and sex. We defined the exposure as severe RSV hospitalization. The main study outcomes were as follows: (1) PHC and ES visits for RSV, categorized using the International Classification of Primary Care codes, (2) prescriptions for respiratory airway obstructive disease, and (3) antibacterial prescriptions. Participants were followed up from 30 days before hospitalization for severe RSV until the outcome occurrence or end of the study. Adjusted incidence rate ratios (IRRs) of the outcomes along with their 95% confidence intervals (CI) were estimated using Poisson regression models. Stratified analyses by type of PHC visit (nurse, pediatrician, or pharmacy) and follow-up period were undertaken. We defined mid-term outcomes as those taking place up to 24 months of follow-up period. The study included 6626 children (3313 RSV-hospitalized; 3313 non-hospitalized) with a median follow-up of 53.7 months (IQR = 27.9, 69.4). After a 3-month follow-up, severe RSV was associated with a considerable increase in PHC visits for wheezing/asthma (IRR = 4.31, 95% CI: 3.84-4.84), lower respiratory infections (IRR = 4.91, 95% CI: 4.34-5.58), and bronchiolitis (IRR = 4.68, 95% CI: 2.93-7.65). Severe RSV was also associated with more PHC visits for the pediatrician (IRR = 2.00, 95% CI: 1.96-2.05), nurse (IRR = 1.89, 95% CI: 1.75-1.92), hospital emergency (IRR = 2.39, 95% CI: 2.17-2.63), primary healthcare emergency (IRR: 1.54, 95% CI: 1.31-1.82), as well as with important increase in prescriptions for obstructive airway diseases (IRR = 5.98, 95% CI: 5.43-6.60) and antibacterials (IRR = 4.02, 95% CI: 3.38-4.81). All findings remained substantial until 2 years of post-infection. Severe RSV infection in infants significantly increases short- to mid-term respiratory morbidity leading to an escalation in healthcare utilization (PHC/ES attendance) and medication prescriptions for up to 2 years afterward. Our approach could be useful in assessing the impact and cost-effectiveness of RSV prevention programs.

Impact of including productivity costs in economic analyses of vaccines for C. difficile infections and infant respiratory syncytial virus, in a UK setting

ObjectivesIt has been estimated that vaccines can accrue a relatively large part of their value from patient and carer productivity. Yet, productivity value is not commonly or consistently considered in health economic evaluations of vaccines in several high-income countries. To contribute to a better understanding of the potential impact of including productivity value on the expected cost-effectiveness of vaccination, we illustrate the extent to which the incremental costs would change with and without productivity value incorporated.MethodsFor two vaccines currently under development, one against Cloistridioides difficile (C. difficile) infection and one against respiratory syncytial disease (RSV), we estimated their incremental costs with and without productivity value included and compared the results.ResultsIn this analysis, reflecting a UK context, a C. difficile vaccination programme would prevent £12.3 in productivity costs for every person vaccinated. An RSV vaccination programme would prevent £49 in productivity costs for every vaccinated person.ConclusionsConsidering productivity costs in future cost-effectiveness analyses of vaccines for C. difficile and RSV will contribute to better-informed reimbursement decisions from a societal perspective.

CROCuS, a Phase II Study Evaluating the Antiviral Activity, Clinical Outcomes, and Safety of Rilematovir in Children Aged ≥28 Days and ≤3 Years with Acute Respiratory Tract Infection Due to Respiratory Syncytial Virus.

Respiratory syncytial virus (RSV) causes significant morbidity and mortality in children aged ≤5 years and adults aged ≥60 years worldwide. Despite this, RSV-specific therapeutic options are limited. Rilematovir is an investigational, orally administered inhibitor of RSV fusion protein-mediated viral entry. To establish the antiviral activity, clinical outcomes, safety, and tolerability of rilematovir (low or high dose) in children aged ≥28days and ≤3years with RSV disease. CROCuS was a multicenter, international, double-blind, placebo-controlled, randomized, adaptive phase II study, wherein children aged ≥28 days and ≤3 years with confirmed RSV infection who were either hospitalized (Cohort 1) or treated as outpatients (Cohort 2) were randomized (1:1:1) to receive rilematovir (low or high dose) or placebo. Study treatment was administered daily as an oral suspension from days 1 to 7, with dosing based on weight and age groups. The primary objective was to establish antiviral activity of rilematovir by evaluating the area under the plasma concentration-time curve of RSV viral load in nasal secretions from baseline through day 5. Severity and duration of RSV signs and symptoms and the safety and tolerability of rilematovir were also assessed through day 28 (±3). In total, 246 patients were randomized, treated, and included in the safety analysis population (Cohort 1: 147; Cohort 2: 99). Of these, 231 were included in the intent-to-treat-infected analysis population (Cohort 1: 138; Cohort 2: 93). In both cohorts, demographics were generally similar across treatment groups. In both cohorts combined, the difference (95% confidence interval) in the mean area under the plasma concentration-time curve of RSV RNA viral load through day 5 was -1.25 (-2.672, 0.164) and -1.23 (-2.679, 0.227) log10 copies∙days/mL for the rilematovir low-dose group and the rilematovir high-dose group, respectively, when compared with placebo. The estimated Kaplan-Meier median (95% confidence interval) time to resolution of key RSV symptoms in the rilematovir low-dose, rilematovir high-dose, and placebo groups of Cohort 1 was 6.01 (4.24, 7.25), 5.82 (4.03, 8.18), and 7.05 (5.34, 8.97) days, respectively; in Cohort 2, estimates were 6.45 (4.81, 9.70), 6.26 (5.41, 7.84), and 5.85 (3.90, 8.27) days, respectively. A similar incidence of adverse events was reported in patients treated with rilematovir and placebo in Cohort 1 (rilematovir: 61.9%; placebo: 58.0%) and Cohort 2 (rilematovir: 50.8%; placebo: 47.1%), with most reported as grade 1 or 2 and none leading to study discontinuation. The study was terminated prematurely, as the sponsor made a non-safety-related strategic decision to discontinue rilematovir development prior to full recruitment of Cohort 2. Data from the combined cohort suggest that rilematovir has a small but favorable antiviral effect of indeterminate clinical relevance compared with placebo, as well as a favorable safety profile. Safe and effective therapeutic options for RSV in infants and young children remain an unmet need. EudraCT Number: 2016-003642-93; ClinicalTrials.gov Identifier: NCT03656510. First posted date: 4 September, 2018.

Cost-utility analysis of palivizumab for preventing respiratory syncytial virus in preterm neonates and infants in Colombia

AimPalivizumab has proven effective in reducing hospitalizations, preventing severe illness, improving health outcomes, and reducing healthcare costs for infants at risk of respiratory syncytial virus (RSV) infection. We aim to assess the value of palivizumab in preventing RSV infection in high-risk infants in Colombia, where RSV poses a significant threat, causing severe respiratory illness and hospitalizations.MethodsWe conducted a decision tree analysis to compare five doses of palivizumab with no palivizumab. The study considered three population groups: preterm neonates (≤ 35 weeks gestational age), infants with bronchopulmonary dysplasia (BPD), and infants with hemodynamically significant congenital heart disease (CHD). We obtained clinical efficacy data from IMpact-RSV and Cardiac Synagis trials, while we derived neonatal hospitalization risks from the SENTINEL-1 study. We based hospitalization and recurrent wheezing management costs on Colombian analyses and validated them by experts. We estimated incremental cost-effectiveness ratios and performed 1,000 Monte Carlo simulations for probabilistic sensitivity analyses.ResultsPalivizumab is a dominant strategy for preventing RSV infection in preterm neonates and infants with BPD and CHD. Its high efficacy (78% in preventing RSV in preterm infants), the substantial risk of illness and hospitalization, and the high costs associated with hospitalization, particularly in neonatal intensive care settings, support this finding. The scatter plots and willingness-to-pay curves align with these results.ConclusionPalivizumab is a cost-saving strategy in Colombia, effectively preventing RSV infection in preterm neonates and infants with BPD and CHD by reducing hospitalizations and lowering healthcare costs.

Assessing the Real-World Effectiveness of Immunizations for Respiratory Syncytial Virus

This Viewpoint discusses recommendations from the US Centers for Disease Control and Prevention for newly licensed immunizations for respiratory syncytial virus in infants, children with high-risk conditions, and older adults.

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

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. 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. 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. 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.

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

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. 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. 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. 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.

Parental awareness and attitudes towards prevention of respiratory syncytial virus in infants and young children in Australia.

To assess parental awareness of respiratory syncytial virus (RSV) and the level of acceptance of future RSV prevention strategies. A cross-sectional online survey was implemented targeting "future" and "current" parents of children aged ≤5 years in Australia. From 1992 eligible participants, two non-mutually exclusive subgroups were formed: "current" parents (N = 1931) and "pregnant/planning" parents (N = 464: 403 also "current" parents and 61 "future" parents). Participants were predominantly (86.6%) aged 25-39 years and 68.5% with university education. The majority (89.6% current; 78.7% future) had heard of RSV. Of those, 64.2% (current) and 50.0% (future) were aware that pneumonia is associated with RSV; 71.8% (current) and 52.1% (future) were aware that bronchiolitis is associated with RSV. In multivariable logistic regression analyses, Australian-born parents (aOR = 2.47 [95% CI: 1.48-4.12]), living in the eastern states (e.g., New South Wales: aOR = 6.15 [95% CI:2.10-18.04]), with a university-level education (aOR = 2.61 [95% CI:1.38-4.94]) and being a current parent (aOR = 12.26 [95% CI:2.82-53.28]) were associated with higher RSV awareness. There was a high level of acceptance for maternal vaccines (future: 79.3%) and infant immunisation (all: 81.7%). While RSV awareness and immunisation acceptance were high, there was limited knowledge of severity of RSV, especially in future parents. Education campaigns need to be developed to increase RSV knowledge.

Birth characteristics as predictors of respiratory syncytial virus hospitalisation in newborns to optimise immunisation schedule.

To examine birth characteristics that influence infant respiratory syncytial virus (RSV) hospitalisation risk in order to identify risk factors for severe RSV infections. Retrospective cohort study of 460 771 Sicilian children under 6 months old from January 2007 to December 2017. Hospital discharge records were consulted to identify cases and hospitalisations with International Classification of Diseases, Ninth Revision, Clinical Modification codes 466.11 (RSV bronchiolitis), 480.1 (RSV pneumonia) and 079.6 (RSV). RSV hospitalisation risk was estimated using adjusted odds ratios (aOR) and 95% confidence intervals (95% CI). Overall, 2420 (5.25 per 1000 infants) RSV-related hospitalisations were identified during the study, with girls accounting for 52.8%. RSV hospitalisation risk increased for full-term, transferred, extreme immature, and preterm neonates with serious issues (aOR 3.25, 95% CI 2.90-3.64; aOR 1.86, 95% CI 1.47-2.32; aOR 1.54, 95% CI 1.11-2.07; and aOR 1.48, 95% CI 1.14-1.90). Compared to children born in June, the risk of RSV hospitalisation was significantly higher in children born in January (aOR 28.09, 95% CI 17.68-48.24) and December (aOR 27.36, 95% CI 17.21-46.99). This study identified birth month and diagnosis-related groups as key predictors of RSV hospitalisations. This could help manage monoclonal antibody appropriateness criteria.

Respiratory Syncytial Virus-related Lower Respiratory Tract Infections in Neonatal and Post-neonatal Babies: A Series of Four Cases

Respiratory Syncytial Virus (RSV) is a highly contagious seasonal virus that is the leading cause of acute Lower Respiratory Tract Infections (LRTI) in the paediatric age group and is one of the leading causes of death in children under five in developing countries. There is evidence that severe RSV infection and hospitalisation in early life increase the risk of recurrent wheezing, childhood asthma, and allergic sensitisation. Even though RSV being a major global health concern, very few papers concentrate on the neonatal period in India. The present case series presents four cases (three females and one male baby) highlighting the impact of RSV in neonatal and post-neonatal infants in India. The cases highlight the diversity of presentation; one infant required prolonged High-flow Nasal Cannula (HFNC) support, while two needed just symptomatic care. The importance of Polymerase Chain Reaction (PCR) in resource-constrained situations is highlighted as diagnostic issues are examined. Treatment focuses on supportive care; oxygen and respiratory support are provided in more severe cases. The present study emphasises the need for early detection and preventative measures, such as using novel treatments like nirsevimab. The present case series advocates for focused therapies and additional research in the Indian paediatric environment, adding insightful perspectives to the expanding body of knowledge on RSV.

Nirsevimab for Prevention of Hospitalizations Due to RSV in Infants

BackgroundThe safety of the monoclonal antibody nirsevimab and the effect of nirsevimab on hospitalizations for respiratory syncytial virus (RSV)–associated lower respiratory tract infection when administered in healthy infants are unclear.MethodsIn a pragmatic trial, we randomly assigned, in a 1:1 ratio, infants who were 12 months of age or younger, had been born at a gestational age of at least 29 weeks, and were entering their first RSV season in France, Germany, or the United Kingdom to receive either a single intramuscular injection of nirsevimab or standard care (no intervention) before or during the RSV season. The primary end point was hospitalization for RSV-associated lower respiratory tract infection, defined as hospital admission and an RSV-positive test result. A key secondary end point was very severe RSV-associated lower respiratory tract infection, defined as hospitalization for RSV-associated lower respiratory tract infection with an oxygen saturation of less than 90% and the need for supplemental oxygen.ResultsA total of 8058 infants were randomly assigned to receive nirsevimab (4037 infants) or standard care (4021 infants). Eleven infants (0.3%) in the nirsevimab group and 60 (1.5%) in the standard-care group were hospitalized for RSV-associated lower respiratory tract infection, which corresponded to a nirsevimab efficacy of 83.2% (95% confidence interval [CI], 67.8 to 92.0; P<0.001). Very severe RSV-associated lower respiratory tract infection occurred in 5 infants (0.1%) in the nirsevimab group and in 19 (0.5%) in the standard-care group, which represented a nirsevimab efficacy of 75.7% (95% CI, 32.8 to 92.9; P=0.004). The efficacy of nirsevimab against hospitalization for RSV-associated lower respiratory tract infection was 89.6% (adjusted 95% CI, 58.8 to 98.7; multiplicity-adjusted P<0.001) in France, 74.2% (adjusted 95% CI, 27.9 to 92.5; multiplicity-adjusted P=0.006) in Germany, and 83.4% (adjusted 95% CI, 34.3 to 97.6; multiplicity-adjusted P=0.003) in the United Kingdom. Treatment-related adverse events occurred in 86 infants (2.1%) in the nirsevimab group.ConclusionsNirsevimab protected infants against hospitalization for RSV-associated lower respiratory tract infection and against very severe RSV-associated lower respiratory tract infection in conditions that approximated real-world settings. (Funded by Sanofi and AstraZeneca; HARMONIE ClinicalTrials.gov number, NCT05437510).

2643. Seasonality of infant respiratory syncytial virus associated bronchiolitis around the US since the onset of COVID-19: Results from four US health systems 2016-2023

Abstract Background Respiratory syncytial virus (RSV) bronchiolitis (Br) is the leading cause of US infant hospitalizations and lower respiratory tract infections [1]. The historical seasonality of RSV in the US across all ages using passive laboratory surveillance has been described by the CDC (2014-17) [2] [3] and more recently by Staadegaard et al [4]. The objective of this analysis is to describe local variation in infant RSV-Br seasonality since the onset of COVID-19 in March 2020, across all facilities and all settings in four health systems across the US, and compare to trends from the recent pre-COVID-19 era. Methods From October 2015-April 2023 we conducted real-time surveillance across all facilities and all settings in the State University of New York (SUNY) Upstate Medical University Health System in Syracuse, NY; the Duke University Health System (DUHS) in Durham, NC; the University of South Florida Health and Tampa General Hospital (TGH) in Tampa, FL; and the Renown Regional Medical Center Health System (Renown) in Reno, NV. We assessed electronic health records (EHR) of infants (0-11 months) using ICD-10 codes for Br and RSV-Br and laboratory testing data to describe infant RSV-Br encounters. For additional methods see Movva N et al [5]. Results During the recent pre-COVID-19 era, there was regional variation in seasonal onset and peak disease burden of infant RSV-Br (Figure 1). Onset and peak disease was earliest at TGH in the southeast and latest at Renown in the west. While occurring outside the historical seasonality timeframe, interseasonal 2021 and early seasonal 2022 infant RSV-Br was similar in duration and followed the same geographic pattern of onset to historical disease. Conclusion After the US onset of COVID-19 in March 2020, the geographic pattern of RSV-Br onset and peaks was preserved, despite the shift to interseasonal and early seasonal disease in 2021 and 2022, respectively. RSV surveillance is useful to determine whether RSV seasonality is returning to typical historic patterns. These results highlight the need for health system-level surveillance and can guide discussion regarding administration of candidate RSV vaccines and immunoprophylaxis and assessment of their impact. Disclosures Mina Suh, MPH, International Health, AstraZeneca: Grant/Research Support|Sanofi: Grant/Research Support|Sobi: Grant/Research Support ZACHARY Wolf, MBA, MS, AstraZeneca: Grant/Research Support|Sanofi: Grant/Research Support Emory Waddell, n/a, Sanofi: Research support Christopher B. Nelson, PhD MPH, Sanofi: employee|Sanofi: employee|Sanofi: Stocks/Bonds|Sanofi: Stocks/Bonds

Inpatient burden of respiratory syncytial virus in children ≤2 years of age in Germany: A retrospective analysis of nationwide hospitalization data, 2019-2022.

Respiratory syncytial virus (RSV) causes respiratory tract disease in seasonal waves, primarily in infants and young children. This study aims to quantify the number of RSV-related hospitalizations in children ≤2 years of age and to determine corresponding resource use and costs in Germany. We retrospectively analyzed population-wide hospital data from the Institute for the Hospital Remuneration System (InEK) from 2019 to 2022. RSV cases were identified using the RSV-specific 10th revision of the International Classification of Diseases (ICD-10) codes J12.1, J20.5, and J21.0. The RSV-associated proportion of all hospitalizations caused by severe acute respiratory infections (SARIs), clinical manifestations, length of stay (LOS), intensive care unit (ICU) admissions, ventilation rates, and hospitalization costs were retrieved. We identified 98,220 hospitalizations (26,052, 15,407, 31,362, and 25,399 in 2019, 2020, 2021, and 2022, respectively) with a principal RSV diagnosis in children aged ≤2 years in Germany. The majority of RSV hospitalizations (73,178) occurred in infants (<1 year), with annual incidence rates ranging from 14.9 to 28.6 per 1000 population. Fifty-eight percent of all SARI hospitalizations in this age group were attributable to RSV. In children aged ≤2 years, mean LOS was 4.5 days, 6.1% of cases were admitted to ICU, and 5.3% of cases were ventilated. Mean hospitalization costs per case ranged from €3001 to €3961 over the study period. RSV causes substantial disease burden and is a leading cause of SARI-related hospital admissions of children ≤2 years of age in Germany. Our results confirm the need to explore and evaluate strategies to prevent RSV in infants and young children.

Society for Maternal-Fetal Medicine Statement: Clinical considerations for the prevention of respiratory syncytial virus disease in infants

Respiratory syncytial virus is a leading cause of lower respiratory tract illness globally in children under 5 years. Each year, approximately 58,000 hospitalizations in the United States are attributed to respiratory syncytial virus. Infants aged 6 months and younger experience the most severe morbidity and mortality. Until recently, prevention with the monoclonal antibody, palivizumab, was only offered to infants with high-risk conditions, and treatment primarily consisted of supportive care. Currently, two products are approved for the prevention of respiratory syncytial virus in infants. These include the Pfizer bivalent recombinant respiratory syncytial virus prefusion F protein subunit vaccine, administered seasonally to the pregnant person between 32 0/7 and 36 6/7 weeks of gestation, and the monoclonal antibody, nirsevimab, administered to infants up to 8 months entering their first respiratory syncytial virus season. With few exceptions, administering both the vaccine to the pregnant person and monoclonal antibody to the infant is not recommended. All infants should be protected against respiratory syncytial virus using one of these strategies. Key considerations for pregnant individuals include examining available safety and efficacy data, weighing accessibility and availability, and patient preferences for maternal vaccination versus infant monoclonal antibody treatment. It will be critical for maternal-fetal medicine physicians to provide effective and balanced counseling to aid patients in deciding on a personalized approach to the prevention of respiratory syncytial virus in their infants.

Cost-Effectiveness of Nirsevimab for the Prevention of Respiratory Syncytial Virus Infection in Infants

&#x0D; During CADTH’s search of the economic literature, 3 economic studies were identified that assessed the cost-effectiveness of a long-acting monoclonal antibody, nirsevimab, as an intervention to prevent respiratory syncytial virus in infants in high-income countries, including 1 study set in Nunavik.&#x0D; The 3 studies were conducted for different geographical locations: Canada, the US, and England and Wales. While each study conducted an economic evaluation, their approaches differed: 1 was a cost-consequence analysis and the other 2 were cost-utility analyses.&#x0D; The results from the 3 studies varied considerably, and the nirsevimab programs differed (e.g., in terms of patients eligible for immunization). In general, nirsevimab was generally more effective and associated with lower total costs than comparator programs. The results were sensitive to the modelled region, source of efficacy data, price of nirsevimab, and severity of the respiratory syncytial virus season.&#x0D; The generalizability of the identified studies to Canadian policy-making may be limited given the population compositions and cost parameters included in the models. To understand the potential cost-effectiveness of nirsevimab, a de novo economic evaluation would be required that compared nirsevimab with the existing preventive strategies employed in Canada (which may include monoclonal antibodies for infants) and is conducted in a Canadian setting.&#x0D;