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

Potential impact of nirsevimab and bivalent maternal vaccine against RSV bronchiolitis in infants: A population-based modelling study

BACKGROUND

A new monoclonal antibody (nirsevimab; Beyfortus®) and a bivalent prefusion RSV vaccine (Abrysvo®) for maternal immunization have been approved recently. This is a modelling study to estimate the potential impact of different immunization programs with these products on RSV-bronchiolitis.

METHODS

Population-based real-world data from primary care and hospitalizations were considered. RSV bronchiolitis dynamics in absence of these immunization scenarios were explained by a multivariate age-structured Bayesian model. Then, the potential impact was simulated under different assumptions including the most recent clinical trial data. Differences in endpoints, populations, and timeframes between trials make the two products' efficacy difficult to compare.

RESULTS

A seasonal with catch-up program, assuming a constant effectiveness of 79.5 % during the first 5 months followed by a linear decay to 0 by month 10 with nirsevimab, would prevent between 5121 and 8846 RSV bronchiolitis per 100,000 infants-years. Assuming 77.3 % effectiveness with the same decay, between 976 and 1686 RSV-hospitalizations per 100,000 infants-years could be prevented depending on the uptake. A year-round maternal immunization program, with 51 % of effectiveness during the first 6 months followed by a linear decay to 0 by month 10 would prevent between 3246 and 5606 RSV bronchiolitis cases per 100,000 infants-years. Assuming 56.9 % effectiveness with the same decay, between 713 and 1231 RSV-hospitalizations per 100,000 infants-years could be prevented.

CONCLUSIONS

Our results suggest that each strategy would effectively reduce RSV-bronchiolitis.

Risk Analysis of Respiratory Syncytial Virus Among Infants in the United States by Birth Month

BACKGROUND

Respiratory syncytial virus (RSV) is a major cause of morbidity and mortality among US infants. A child's calendar birth month determines their age at first exposure(s) to RSV. We estimated birth month-specific risk of medically attended (MA) RSV lower respiratory tract infection (LRTI) among infants during their first RSV season and first year of life (FYOL).

METHODS

We analyzed infants born in the USA between July 2016 and February 2020 using three insurance claims databases (two commercial, one Medicaid). We classified infants' first MA RSV LRTI episode by the highest level of care incurred (outpatient, emergency department, or inpatient), employing specific and sensitive diagnostic coding algorithms to define index RSV diagnoses. In our main analysis, we focused on infants' first RSV season. In our secondary analysis, we compared the risk of MA RSV LRTI during infants' first RSV season to that of their FYOL.

RESULTS

Infants born from May through September generally had the highest risk of first-season MA RSV LRTI-approximately 6-10% under the specific RSV index diagnosis definition and 16-26% under the sensitive. Infants born between October and December had the highest risk of RSV-related hospitalization during their first season. The proportion of MA RSV LRTI events classified as inpatient ranged from 9% to 54% (specific) and 5% to 33% (sensitive) across birth month and comorbidity group. Through the FYOL, the overall risk of MA RSV LRTI is comparable across birth months within each claims database (6-11% under the specific definition, 17-30% under the sensitive), with additional cases progressing to care at outpatient or ED settings.

CONCLUSIONS

Our data support recent national recommendations for the use of nirsevimab in the USA. For infants born at the tail end of an RSV season who do not receive nirsevimab, a dose administered prior to the onset of their second RSV season could reduce the incidence of outpatient- and ED-related events.

Impact of universal immunization program with monoclonal antibody nirsevimab on reducing the burden of serious bronchiolitis that need pediatric intensive care

RSV bronchiolitis remains the leading cause of hospitalization in children under 1 year of age. It is estimated that 2-6% of cases will be hospitalized on pediatric intensive care units (PICUs). In October 2023, a universal immunization program with the monoclonal antibody nirsevimab was implemented in Catalonia. The aim of the study was to analyze the impact of the nirsevimab immunization on the burden of bronchiolitis admitted to a PICU and resulting changes in epidemiological, clinical, and microbiological characteristics comparing the pre-nirsevimab (pre-N) with the post-nirsevimab (post-N) period. This was a prospective, descriptive, and observational study. Patients with severe bronchiolitis admitted to reference children's hospital PICU, between September 2010 and February 2024 were included. Demographic and clinical data were collected and viral laboratory etiological diagnosis was carried out. 1531 patients were recruited, 1458 in the pre-N seasons and 73 after its introduction (58% males, median age 52 days), of which 67% were immunized with nirsevimab. The total number of PICU bronchiolitis admissions, the ratio, and the RSV etiology were significantly lower in the post-N period (p = 0.03, p < 0.001, and p = 0.039, respectively). Significant higher age at admission (p < 0.001) and lower hospital length of stay (p < 0.001) was observed comparing pre-N vs. post-N period.

CONCLUSION

Nirsevimab appears to have an important impact on reducing the number and length of stay of PICU admissions due to RSV bronchiolitis.

WHAT IS KNOWN

• Bronchiolitis is the most common viral infection of the lower respiratory tract in infants. • It represents 13% of the total pediatric intensive care admissions, typically during winter. This is one of the causes that produces a collapse in the health care systems all around the world.

WHAT IS NEW

• In October 2023, universal immunization with monoclonal antibody nirsevimab of all children under 6 months of age was started in the majority of autonomous communities in Spain. • Recent publications from the nirsevimab clinical trials have evidenced a high RSV protective effect, but data on its effect on real life patients who require pediatric intensive care unit admission are missing.

High Uptake of Respiratory Syncitial Virus Prevention for Neonates in a Military Treatment Facility

We investigated the uptake of nirsevimab for infants and the bivalent respiratory syncytial virus prefusion F (RSVPreF) vaccine for pregnant persons as measures for RSV prevention during an infant's birth hospitalization in a military treatment facility. We found >85% uptake between October 2023 to February 2024. These data may aid health systems plan for future RSV seasons.

Trends in RSV testing patterns among infants presenting with bronchiolitis: Results from four United States health systems, 2015-2023

BACKGROUND

Bronchiolitis due to respiratory syncytial virus (RSV) is the leading cause of hospitalization among American infants. The overall burden of RSV among infants has been historically under-estimated due to variable testing practices, particularly in the outpatient setting. Universal masking and social distancing implemented during the coronavirus disease 2019 (COVID-19) pandemic altered RSV seasonality, however potential consequences on RSV testing practices across different healthcare settings and sociodemographic groups have not been described. Variable testing practices could also affect accurate assessment of the effects of two recently approved RSV preventative agents targeting infants.

METHODS

Utilizing real-time clinical and viral surveillance, we examined RSV testing practices among infants with bronchiolitis within four United States healthcare systems across different healthcare settings and sociodemographic groups pre- and post-COVID-19.

RESULTS

RSV testing among infants with bronchiolitis increased since 2015 within each healthcare system across all healthcare settings and sociodemographic groups, with a more dramatic increase since the COVID-19 pandemic. Outpatient testing remained disproportionately low compared to hospital-based testing, although there were no major differences in testing frequency among sociodemographic groups in either setting.

CONCLUSIONS

Although RSV testing increased among infants with bronchiolitis, relatively low outpatient testing rates remain a key barrier to accurate RSV surveillance.

Xuanfei Formula inhibited RSV infection by normalizing the SREBP2-mediated cholesterol synthesis process

Background and aims

Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infections in children and the elderly, often progressing to pneumonia and severe sequelae. However, there are currently no feasible and cost-effective interventions with proven efficacy for children, making medications with anti-RSV activity urgently needed. Traditional Chinese medicine has shown promising therapeutic efficacy in alleviating viral infection symptoms. Therefore, we aimed to develop effective strategies for RSV treatment based on traditional Chinese medicine.

Methods and results

The infection status was assessed in BALB/c mice with or without Xuanfei Formula (XFF) treatment over a one-week period using H&E staining, cytokine assays and RSV titer testing after RSV challenge. Remarkably, on the first day of XFF intervention, both the pro-inflammation cytokine levels in the serum and RSV-N gene copies in the lung of mice were plummeted, compared to the RSV-infected group. This implied that XFF might possess the immune-independent anti-RSV capability. To elucidate the underlying mechanism, we employed transcriptome analysis followed by k-means analysis. The reversal effects of XFF against RSV primarily focused on the processes of innate and adaptive immunity. Additionally, we found that XFF administration corrected the disordered fatty acid and cholesterol metabolism processes during RSV infection. Lipidomics profiling indicated consistent cholesterol abundance with transcriptional changes but not fatty acids. Cholesterol synthesis-related genes mRNA levels and cholesterol synthesis intermediates detection supported XFF's repression upon cholesterol biosynthesis. Aberrantly increased cholesterol production has been reported as necessary for RSV infection. To mimic that, we observed lovastatin treatment inhibited RSV replication and pro-inflammation cytokine expression in vitro. Transcription factor prediction of differentially expressed genes (DEGs) involved in cholesterol synthesis implicated SREBP2. Through network pharmacology, stigmasterol and β-sitosterol were identified as the effective active ingredients within the XFF, with the help of further molecular docking and mass spectrum detection. In vitro experiments demonstrated β-sitosterol and stigmasterol reinforced the bonding between SREBP cleavage-activation protein (SCAP) and insulin-induced gene proteins (INSIGs) to inhibit SREBP2 cleavage maturation and consequent RSV infection.

Conclusion

Xuanfei Formula (XFF) exhibits excellent anti-RSV efficacy by inhibiting SREBP2-mediated cholesterol synthesis to reduce RSV replication and ameliorate inflammation in the lung of infected mice.

The increase of bronchiolitis severity in the 2022-2023 season in an Italian tertiary children's hospital: An isolated phenomenon or a warning sign?

AIM

Recent literature has shown epidemiological changes in bronchiolitis with an increased incidence in the post-SARS-CoV-2 pandemic period but reports regarding disease severity are conflicting. We aimed to describe the epidemiology, disease severity, and microbiology of bronchiolitis during the 2022-2023 cold season compared to the previous 5 years.

METHODS

This single-center retrospective observational study at IRCCS Gaslini, Italy, included all children aged 0-2 years hospitalized for bronchiolitis from 1 September 2017 to 31 August 2023. Findings from the 2022-2023 season were compared to the previous 5 years.

RESULTS

We observed a statistically significant increase in the 2022-2023 season in the absolute number of bronchiolitis admissions. Children who required mechanical ventilation (MV) dramatically increased from a total of seven patients in the previous five seasons to 17 in the 2022-2023 season alone (p = .001). All other severity parameters significantly increased: the need for respiratory support (p = .002), the median length of stay (5 days vs. 4 days, p = .001), and the median duration of respiratory support (4 days vs. 3 days, p = .016).

CONCLUSIONS

We report a substantial increase in the severity of bronchiolitis in the season 2022-2023 with a remarkable number of previously healthy infants requiring MV. Further studies are needed to confirm whether our findings are an isolated phenomenon or part of a true global trend. Health systems need to be prepared and protective preventive measures should be implemented for all newborns.

Nirsevimab: Expansion of Respiratory Syncytial Virus Prevention Options in Neonates, Infants, and At-Risk Young Children

OBJECTIVE

Review available data from clinical trials of nirsevimab for efficacy and safety in the setting of respiratory syncytial virus (RSV) prophylaxis in infants and children, while exploring nirsevimab's role in clinical practice and highlighting continuing questions.

DATA SOURCES

A literature search of PubMed was conducted utilizing the phrases "nirsevimab" and "medi8897." Additional references were identified through found references. Organizational guidelines, medication labeling, and regulatory organization presentations were utilized.

STUDY SELECTION AND DATA EXTRACTION

Relevant clinical trials investigating nirsevimab in infants and children were included as well as other references on pharmacology, pharmacokinetics, and pharmacoeconomics.

DATA SYNTHESIS

Nirsevimab, a once-a-season monoclonal antibody, demonstrated a 79.5% (95% CI, 65.9-87.7; P < 0.00001) lower incidence of RSV-associated medically attended lower respiratory tract infections (MA RSV-associated LRTI) and 77.3% (95% CI, 50.3-89.7; P = 0.0002) reduction in hospitalizations for RSV-associated MA-LRTI across 2 placebo-controlled studies. Nirsevimab demonstrated comparable safety to placebo with minor dermatologic reactions being the most common adverse event (0.9% vs 0.6%).

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE IN COMPARISON WITH EXISTING AGENTS

Nirsevimab was approved by the US Food and Drug Administration, and recommended by the Advisory Committee on Immunization Practices and American Academy of Pediatrics for broad administration to infants entering their first RSV season and at risk patients during their second RSV season. Questions remain over efficacy in infants born < 29-week gestation and other economical considerations.

CONCLUSIONS

Nirsevimab demonstrated clinical efficacy in reducing RSV-associated MA-LRTI and RSV-associated hospitalizations in infants and was well tolerated.

Balanced on the Biggest Wave: Nirsevimab for Newborns

Respiratory syncytial virus (RSV) is the leading cause of hospitalization in infancy in the United States. Nearly all infants are infected by 2 years of age, with bronchiolitis requiring hospitalization often occurring in previously healthy children and long-term consequences of severe disease including delayed speech development and asthma. Incomplete passage of maternal immunity and a high degree of genetic variability within the virus contribute to morbidity and have also prevented successful neonatal vaccine development. Monoclonal antibodies reduce the risk of hospitalization from severe RSV disease, with palivizumab protecting high-risk newborns with comorbidities including chronic lung disease and congenital heart disease. Unfortunately, palivizumab is costly and requires monthly administration of up to five doses during the RSV season for optimal protection.Rapid advances in the past two decades have facilitated the identification of antibodies with broad neutralizing activity and allowed manipulation of their genetic code to extend half-life. These advances have culminated with nirsevimab, a monoclonal antibody targeting the Ø antigenic site on the RSV prefusion protein and protecting infants from severe disease for an entire 5-month season with a single dose. Four landmark randomized controlled trials, the first published in July 2020, have documented the efficacy and safety of nirsevimab in healthy late-preterm and term infants, healthy preterm infants, and high-risk preterm infants and those with congenital heart disease. Nirsevimab reduces the risk of RSV disease requiring medical attention (number needed to treat [NNT] 14-24) and hospitalization (NNT 33-63) with rare mild rash and injection site reactions. Consequently, the Centers for Disease Control and Prevention has recently recommended nirsevimab for all infants younger than 8 months of age entering or born during the RSV season and high-risk infants 8-19 months of age entering their second season. Implementing this novel therapy in this large population will require close multidisciplinary collaboration. Equitable distribution through minimizing barriers and maximizing uptake must be prioritized.

Outpatient respiratory syncytial virus infections and novel preventive interventions

PURPOSE OF REVIEW

With interventions to prevent respiratory syncytial virus (RSV) infection within reach, this review aims to provide healthcare professionals with the latest information necessary to inform parents and assess the potential impact of RSV prevention on everyday practice. We address frequently asked questions for parental counseling.

RECENT FINDINGS

Numerous studies emphasize the major burden of RSV on young children, parents, healthcare and society. In the first year of life, about 14% of healthy term infants visit a doctor and 2% require hospitalization due to RSV. In older children (1--5 years), RSV infections and associated morbidity (wheeze, acute otitis media) are major drivers of outpatient visits. A novel maternal RSV vaccine and long-acting mAb can provide protection during infants' first months of life. This maternal vaccine showed 70.9% efficacy against severe RSV infection within 150 days after birth; the mAb nirsevimab reduces medically attended RSV infections by 79.5% within 150 days after administration. Both gained regulatory approval in the USA (FDA) and Europe (EMA).

SUMMARY

Novel RSV immunizations hold promise to reduce the RSV burden in infants, with substantial impact on everyday practice. Tailored parental guidance will be instrumental for successful implementation. Awaiting pediatric vaccines, RSV infections beyond infancy will still pose a significant outpatient burden.

Sociodemographic Factors and Trends in Bronchiolitis-Related Emergency Department Visit and Hospitalization Rates

Importance

Bronchiolitis is the most common and most cumulatively expensive condition in pediatric hospital care. Few population-based studies have examined health inequalities in bronchiolitis outcomes over time.

Objective

To examine trends in bronchiolitis-related emergency department (ED) visit and hospitalization rates by sociodemographic factors in a universally funded health care system.

Design, Setting, and Participants

This repeated cross-sectional cohort study was performed from April 1, 2004, to March 31, 2022, using population-based health administrative data from children younger than 2 years in Ontario, Canada.

Main Outcome and Measures

Bronchiolitis ED visit and hospitalization rates per 1000 person-years reported for the equity stratifiers of sex, residence location (rural vs urban), and material resources quintile. Trends in annual rates by equity stratifiers were analyzed using joinpoint regression and estimating the average annual percentage change (AAPC) with 95% CI and the absolute difference in AAPC with 95% CI from April 1, 2004, to March 31, 2020.

Results

Of 2 921 573 children included in the study, 1 422 088 (48.7%) were female and 2 619 139 (89.6%) lived in an urban location. Emergency department visit and hospitalization rates were highest for boys, those with rural residence, and those with least material resources. There were no significant between-group absolute differences in the AAPC in ED visits per 1000 person-years by sex (female vs male; 0.22; 95% CI, -0.92 to 1.35; P = .71), residence (rural vs urban; -0.31; 95% CI -1.70 to 1.09; P = .67), or material resources (quintile 5 vs 1; -1.17; 95% CI, -2.57 to 0.22; P = .10). Similarly, there were no significant between-group absolute differences in the AAPC in hospitalizations per 1000 person-years by sex (female vs male; 0.53; 95% CI, -1.11 to 2.17; P = .53), residence (rural vs urban; -0.62; 95% CI, -2.63 to 1.40; P = .55), or material resources (quintile 5 vs 1; -0.93; 95% CI -3.80 to 1.93; P = .52).

Conclusions and Relevance

In this population-based cohort study of children in a universally funded health care system, inequalities in bronchiolitis ED visit and hospitalization rates did not improve over time.

Recent advances in the prevention of respiratory syncytial virus in pediatrics

PURPOSE OF REVIEW

Respiratory syncytial virus (RSV) is a ubiquitous virus and the leading cause of pediatric hospitalization in the United States. Prevention strategies are key for reducing the burden of RSV. Several new agents aimed at preventing RSV in infants and children were FDA-approved in 2023, and many more are in the development pipeline. This review highlights new developments in RSV prevention in pediatric patients and the important safety considerations for clinical trials.

RECENT FINDINGS

Two new preventive therapies were FDA approved in 2023; a maternal vaccine (Abrysvo) and a mAb (Beyfortus) have both demonstrated reduction in medically attended lower respiratory tract infections in infants and children. Evaluation of ongoing clinical trials demonstrates that the field is expanding further to include direct immunization of infants and children utilizing a variety of delivery modalities. While these developments present the optimistic prospect of RSV prevention in a range of ages, acute and long-term risks must be carefully evaluated.

SUMMARY

Prevention of RSV is more accessible than ever, but careful consideration must be given to risks associated with new and developing prevention strategies. Rigor of clinical trials including longitudinal outcomes of agents in development and postmarketing surveillance of newly approved therapies will be of paramount importance to ensure long-term safety of new RSV prevention strategies.

Respiratory Syncytial Virus (RSV) Burden in Infants in the Kingdom of Saudi Arabia and the Impact of All-Infant RSV Protection: A Modeling Study

INTRODUCTION

Respiratory syncytial virus (RSV) represents a considerable burden on the healthcare system and hospital resources. This study explored the impact of universal immunoprophylaxis with long-acting monoclonal antibody (nirsevimab) during infants' first RSV season on RSV-induced health events and related costs in the Kingdom of Saudi Arabia (KSA).

METHODS

The burden of RSV-induced health events and related costs under the current standard of practice (SoP) and the impact of universal immunoprophylaxis with nirsevimab was estimated using a static decision-analytic model in a cohort of infants experiencing their first RSV season in the KSA. The model estimated hospital admissions (including pediatric intensive care unit [PICU] admissions and mechanical ventilation [MV]), emergency room (ER) visits, primary care (PC) visits, long-term sequelae, and RSV mortality.

RESULTS

The model estimated that under the current SoP, RSV results in 17,179-19,607 hospitalizations (including 2932-3625 PICU and 172-525 MV admissions), 57,654-191,115 ER visits, 219,053-219,970 PC visits, 14 deaths, 12,884-14,705 cases of recurrent wheezing, and a total cost of SAR 480-619 million. Universal nirsevimab immunoprophylaxis was estimated to avert 58% of hospitalizations (58% PICU admissions, 58% MV episodes), 53% of ER visits, 53% of PC visits, 58% of episodes of recurrent wheezing, 8 deaths, and result in savings of SAR 274-343 million in total healthcare cost.

CONCLUSION

Compared with current SoP, an nirsevimab immunoprophylaxis strategy in the KSA for all infants during their first RSV season was estimated to dramatically decrease healthcare resource use, and economic burden associated with RSV.

Determining the timing of respiratory syncytial virus (RSV) epidemics: a systematic review, 2016 to 2021; method categorisation and identification of influencing factors

BackgroundThere is currently no standardised approach to estimate respiratory syncytial virus (RSV) epidemics' timing (or seasonality), a critical information for their effective prevention and control.AimWe aimed to provide an overview of methods to define RSV seasonality and identify factors supporting method choice or interpretation/comparison of seasonal estimates.MethodsWe systematically searched PubMed and Embase (2016-2021) for studies using quantitative approaches to determine the start and end of RSV epidemics. Studies' features (data-collection purpose, location, regional/(sub)national scope), methods, and assessment characteristics (case definitions, sampled population's age, in/outpatient status, setting, diagnostics) were extracted. Methods were categorised by their need of a denominator (i.e. numbers of specimens tested) and their retrospective vs real-time application. Factors worth considering when choosing methods and assessing seasonal estimates were sought by analysing studies.ResultsWe included 32 articles presenting 49 seasonality estimates (18 thereof through the 10% positivity threshold method). Methods were classified into eight categories, two requiring a denominator (1 retrospective; 1 real-time) and six not (3 retrospective; 3 real-time). A wide range of assessment characteristics was observed. Several studies showed that seasonality estimates varied when methods differed, or data with dissimilar assessment characteristics were employed. Five factors (comprising study purpose, application time, assessment characteristics, healthcare system and policies, and context) were identified that could support method choice and result interpretation.ConclusionMethods and assessment characteristics used to define RSV seasonality are heterogeneous. Our categorisation of methods and proposed framework of factors may assist in choosing RSV seasonality methods and interpretating results.

Nirsevimab Immunization to Prevent Respiratory Syncytial Virus-Associated Lower Respiratory Tract Infections in Infants and Children up to 24 Months of Age

Respiratory syncytial virus (RSV) infects nearly all infants in their first year of life and is the leading cause of hospitalization for infants younger than 1 year of age in the United States. Historically, the only option for RSV prevention was palivizumab. However, not all infants are eligible for palivizumab, it requires multiple doses per RSV season, and it is costly. In July 2023, the U.S. Food and Drug Administration approved nirsevimab for the prevention of RSV-associated lower respiratory tract infections for all infants. Nirsevimab inhibits RSV from fusing to cellular membranes and thereby neutralizes the virus in the body. Nirsevimab is expected to significantly reduce the health and economic burdens of RSV. This article provides an overview of nirsevimab, potential adverse effects, and implications for nursing practice.

Cost-effectiveness analysis of nirsevimab and maternal RSVpreF vaccine strategies for prevention of Respiratory Syncytial Virus disease among infants in Canada: a simulation study

Background

The cost-effectiveness of immunisation strategies with a long-acting monoclonal antibody (nirsevimab) and/or a protein-based maternal vaccine (RSVpreF) for protecting infants from Respiratory Syncytial Virus (RSV)-associated illness has not been previously determined for Canada. We estimated the health benefits and cost-effectiveness of nirsevimab for immunising the entire birth cohort, regardless of gestational age or other risk factors. Additionally, we evaluated the health benefits and cost-effectiveness of a combined strategy of year-round vaccination of pregnant women with RSVpreF and immunisation of infants at high risk, including those born preterm or with chronic conditions, with nirsevimab during the RSV season.

Methods

We developed a discrete-event simulation model, parameterized with the data on medically-attended RSV infections among infants under one year of age from 2010 to 2019, including outpatient care, hospitalisations, and deaths. Intervention scenarios targeting twelve monthly birth cohorts and pregnant women, reflecting the 2021 census data for Ontario, Canada were evaluated over a follow-up time horizon of one year from birth. Taking into account the costs (in 2023 Canadian dollars) associated with RSV-related outcomes, we calculated the net monetary benefit using the quality-adjusted life-year (QALY) gained. Further, we determined the range of price-per-dose (PPD) for nirsevimab and RSVpreF within which the program was cost-effective. Cost-effectiveness analyses were conducted from both healthcare and societal perspectives.

Findings

Using a willingness-to-pay of CAD$50,000 per QALY gained, we found that immunising the entire birth cohort with nirsevimab would be cost-effective from a societal perspective for a PPD of up to $290, with an annual budget impact of $83,978 for 1113 infants per 100,000 population. An alternative, combined strategy of vaccinating pregnant women and immunising only infants at high risk of severe disease would lead to a lower budget impact of $49,473 per 100,000 population with a PPD of $290 and $195 for nirsevimab and RSVpreF vaccine, respectively. This combined strategy would reduce infant mortality by 76%-85%, comparable to a 78% reduction achieved through a nirsevimab-only program of the entire birth cohort. The PPD for cost-effective programs with nirsevimab was sensitive to the target population among infants.

Interpretation

Passive immunisation of infants under 6 months of age with nirsevimab and vaccination of pregnant women with RSVpreF could be a cost-effective strategy for protecting infants during their first RSV season.

Funding

This study was supported by the Canadian Immunisation Research Network (CIRN) and the Canadian Institutes of Health Research (CIHR). Seyed M. Moghadas acknowledges support from the Natural Sciences and Engineering Research Council of Canada (MfPH and Discovery grants). Alison P. Galvani acknowledges support from the The Notsew Orm Sands Foundation.

Hospitalization for bronchiolitis in children aged ≤ 1year, Southern Italy, year 2021: need for new preventive strategies?

BACKGROUND

Bronchiolitis is a major cause of hospitalization in infants, particularly in the first six months of life, with approximately 60-80% of admissions due to respiratory syncytial virus (RSV) infection. Currently, no prophylactic options are available for healthy infants. The present study aimed at describing the demographic, clinical, and epidemiological characteristics of infants hospitalized for bronchiolitis in the Apulia region of Italy in 2021.

METHODS

From January to December 2021, data on children aged 0-12 months admitted for bronchiolitis in nine neonatal or pediatric units covering 61% of pediatric beds of hospitals in the Apulia region of Italy were analyzed. Demographic data, comorbidities, need for oxygen support, length of hospital stay, palivizumab administration, and outcomes were collected. For the purpose of the analysis, patients were divided into those aged 0-3 months and > 3 months. A multivariate logistic regression model was used to explore associations between the need for oxygen support and sex, age, comorbidities, history of prematurity, length of hospital stay, and palivizumab administration.

RESULTS

This study included 349 children aged 0-12 months admitted for bronchiolitis, with a peak of hospitalization in November (7.4 cases/1,000 children). Of these patients, 70.5% were RSV positive, 80.2% were aged 0-3 months, and 73.1% required oxygen support. Moreover, 34.9% required observation in the sub-intensive care unit, and 12.9% in the intensive care unit. Of the infants who required intensive care, 96.9% were aged 0-3 months and 78.8% were born at term. Three patients required mechanical ventilation and one, who required Extra Corporeal Membrane Oxygenation, died. Children aged 0-3 months were more likely to show dyspnea, need oxygen support, and have a longer hospital stay.

CONCLUSIONS

The present study showed that almost all of the children who required intensive care support were aged ≤ 3 months and most were born at term. Therefore, this age group remains the highest risk group for severe bronchiolitis. Preventive measures such as single-dose monoclonal antibody immunoprophylaxis, and maternal and childhood vaccination against RSV, may reduce the high public health burden of bronchiolitis.

Quality of life burden on United States infants and caregivers due to lower respiratory tract infection and adjusting for selective testing: Pilot prospective observational study

Background and Aims

Policymakers need data about the burden of respiratory syncytial virus (RSV) lower respiratory tract infections (LRTI) among infants. This study estimates quality of life (QoL) for otherwise healthy term US infants with RSV-LRTI and their caregivers, previously limited to premature and hospitalized infants, and corrects for selective testing.

Methods

The study enrolled infants <1 year with a clinically diagnosed LRTI encounter between January and May 2021. Using an established 0-100 scale, the 36 infants' and caregivers' QoL at enrollment and quality-adjusted life year losses per 1000 LRTI episodes (quality-adjusted life years [QALYs]/1000) were validated and analyzed. Regression analyses examined predictors of RSV-testing and RSV-positivity, creating modeled positives.

Results

Mean QoL at enrollment in outpatient (n = 11) LRTI-tested infants (66.4) was lower than that in not-tested LRTI infants (79.6, p = 0.096). For outpatient LRTI infants (n = 23), median QALYs/1000 losses were 9.8 and 0.25 for their caregivers. RSV-positive outpatient LRTI infants (n = 6) had significantly milder QALYs/1000 losses (7.0) than other LRTI-tested infants (n = 5)(21.8, p = 0.030). Visits earlier in the year were more likely to be RSV-positive than later visits (p = 0.023). Modeled RSV-positivity (51.9%) was lower than the observed rate (55.0%). Infants' and caregivers' QALYs/1000 loss were positively correlated (rho = 0.34, p = 0.046), indicating that infants perceived as sicker imposed greater burdens on caregivers.

Conclusions

The overall median QALYs/1000 losses for LRTI (9.0) and RSV-LRTI (5.6) in US infants are substantial, with additional losses for their caregivers (0.25 and 0.20, respectively). These losses extend equally to outpatient episodes. This study is the first reporting QALY losses for infants with LRTI born at term or presenting in nonhospitalized settings, and their caregivers.

Monoclonal antibodies for prophylaxis and therapy of respiratory syncytial virus, SARS-CoV-2, human immunodeficiency virus, rabies and bacterial infections: an update from the World Association of Infectious Diseases and Immunological Disorders and the Italian Society of Antinfective Therapy

Monoclonal antibodies (mABs) are safe and effective proteins produced in laboratory that may be used to target a single epitope of a highly conserved protein of a virus or a bacterial pathogen. For this purpose, the epitope is selected among those that play the major role as targets for prevention of infection or tissue damage. In this paper, characteristics of the most important mABs that have been licensed and used or are in advanced stages of development for use in prophylaxis and therapy of infectious diseases are discussed. We showed that a great number of mABs effective against virus or bacterial infections have been developed, although only in a small number of cases these are licensed for use in clinical practice and have reached the market. Although some examples of therapeutic efficacy have been shown, not unlike more traditional antiviral or antibacterial treatments, their efficacy is significantly greater in prophylaxis or early post-exposure treatment. Although in many cases the use of vaccines is more effective and cost-effective than that of mABs, for many infectious diseases no vaccines have yet been developed and licensed. Furthermore, in emergency situations, like in epidemics or pandemics, the availability of mABs can be an attractive adjunct to our armament to reduce the impact. Finally, the availability of mABs against bacteria can be an important alternative, when multidrug-resistant strains are involved.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Cost-Effectiveness of Respiratory Syncytial Virus Preventive Interventions in Children: A Model Comparison Study

OBJECTIVES

Model-based cost-effectiveness analyses on maternal vaccine (MV) and monoclonal antibody (mAb) interventions against respiratory syncytial virus (RSV) use context-specific data and produce varied results. Through model comparison, we aim to characterize RSV cost-effectiveness models and examine drivers for their outputs.

METHODS

We compared 3 static and 2 dynamic models using a common input parameter set for a hypothetical birth cohort of 100 000 infants. Year-round and seasonal programs were evaluated for MV and mAb interventions, using available evidence during the study period (eg, phase III MV and phase IIb mAb efficacy).

RESULTS

Three static models estimated comparable medically attended (MA) cases averted versus no intervention (MV, 1019-1073; mAb, 5075-5487), with the year-round MV directly saving ∼€1 million medical and €0.3 million nonmedical costs, while gaining 4 to 5 discounted quality-adjusted life years (QALYs) annually in <1-year-olds, and mAb resulting in €4 million medical and €1.5 million nonmedical cost savings, and 21 to 25 discounted QALYs gained. In contrast, both dynamic models estimated fewer MA cases averted (MV, 402-752; mAb, 3362-4622); one showed an age shift of RSV cases, whereas the other one reported many non-MA symptomatic cases averted, especially by MV (2014). These differences can be explained by model types, assumptions on non-MA burden, and interventions' effectiveness over time.

CONCLUSIONS

Our static and dynamic models produced overall similar hospitalization and death estimates, but also important differences, especially in non-MA cases averted. Despite the small QALY decrement per non-MA case, their larger number makes them influential for the costs per QALY gained of RSV interventions.

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

Background

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

Objective

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

Methods

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

Results

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

Conclusions

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