Cost-effectiveness of nirsevimab and palivizumab for respiratory syncytial virus prophylaxis in preterm infants 29-34 6/7 weeks' gestation in the United States

Impact of Nirsevimab immunoprophylaxis on professional exhaustion during two epidemics of respiratory syncytial virus

OBJECTIVE

We aimed to assess the impact of introducing immunoprophylaxis against respiratory syncytial virus in infants (healthy infants up to 6 months of age and vulnerable children up to 24 months) on the professional quality of life of pediatric healthcare providers, and to analyze its association with factors such as sex, age, work experience, workplace setting, professional role, and involvement in pediatric emergency departments.

METHODS

We conducted an observational, analytical, cross-sectional, multicenter study in Valencia and Castellon Health Departments. The Professional Quality of Life Scale (ProQOL-21) was used to assess compassion satisfaction, burnout, and secondary traumatic stress, the latter two being components of compassion fatigue. Data were collected during two bronchiolitis periods: 2022-2023 (pre-Nirsevimab) and 2023-2024 (post-Nirsevimab). These three dimensions were analyzed across both periods and in relation to demographic and professional variables.

RESULTS

A total of 213 surveys were collected (113 pre-Nirsevimab and 100 post-Nirsevimab). The results revealed a significant decrease in burnout and secondary traumatic stress, along with an increase in compassion satisfaction. Improvements were particularly notable among professionals working in emergency departments, hospitals, those under 35 years of age, women, and those with less than 10 years of work experience. No significant improvements were observed in men or residents across any of the dimensions.

IMPLICATIONS FOR PRACTICE

The implementation of immunoprophylaxis against respiratory syncytial virus has not only improved patient outcomes but has also positively impacted the emotional well-being of pediatric healthcare providers, highlighting the importance of implementing preventive strategies to support healthcare professionals.

Administration of Nirsevimab for RSV Prophylaxis in Infants: A Comprehensive Review

Respiratory syncytial virus (RSV) is the primary etiological agent responsible for lower respiratory tract infections (LRTIs) and hospitalizations among infants. Nirsevimab, a novel monoclonal antibody (mAb), offers sustained protection against RSV for a minimum of 5 months in neonates and young children. Extensive clinical trials and real-world evidence have demonstrated that nirsevimab significantly mitigates the incidence and severity of RSV infections in infants, while exhibiting favorable safety profiles and cost-effectiveness. Regulatory authorities in multiple countries have approved nirsevimab, and its implementation is progressively expanding across various healthcare settings. However, several critical issues require further attention. Specifically, a more in-depth investigation into the long-term efficacy and benefits of nirsevimab across diverse populations, particularly neonates, is essential. Additionally, accelerating the introduction and administration of nirsevimab in developing countries remains imperative. Thus, this review comprehensively summarizes the administration of nirsevimab in infants to facilitate its broader application.

Early Experience on Universal Prophylaxis in Infants against Respiratory Syncytial Virus: Facts and Expectations

During the 2023/24 season, nirsevimab significantly reduced the risk of bronchiolitis and confirmed respiratory syncytial virus (RSV) infections in primary care, hospital, and pediatric intensive care unit admissions among infants aged 0 to 11 months, even in a season with a high community RSV burden, particularly for older infants. These findings are very useful for public health authorities to continue to implement immunization campaigns against RSV in the coming seasons. Moreover, universal immunization against RSV represents a transformative step toward reducing the burden of RSV in infants. With promising evidence from recently published studies, the expectations for a reduction of RSV-associated hospitalizations, alongside the improvement of public health outcomes and equitable access to these measures, are high. However, achieving these goals will require addressing challenges related to vaccine uptake, funding, and RSV surveillance to prompt detect resistances due to mutations of the virus. These interventions need to be integrated into public health strategies because they hold the potential to make a significant impact on infant's health worldwide.

Respiratory Syncytial Virus Burden in Premature Infants: The Role of Season With and Without RSV Immunoprophylaxis in a Multicenter Study

OBJECTIVE

To compare the Respiratory Syncytial Virus (RSV) hospitalization burden among 29-34 weeks gestational age (wGA) preterm infants between seasons with and without routine palivizumab prophylaxis, by utilizing the 2021 off-season RSV surge.

METHODS

This multi-center retrospective study was conducted in 11 medical centers across Israel. We included infants > 1 year-old, with wGA data, hospitalized with RSV infection from November 2017-August 2021. National palivizumab compliance data were collected separately. We compared two periods: in-season (November-March) with routine palivizumab prophylaxis as the reference, and off-season (April-October) without prophylaxis as the primary risk factor. The primary outcome was the proportion of RSV hospitalizations in 29-34 wGA infants relative to total RSV admissions, calculated separately for each period. Secondary outcomes included clinical severity parameters.

RESULTS

A total of 3296 infants were admitted during the RSV in-season, and 1044 during the off-season. National palivizumab compliance among eligible infants during the in-season study years was 91%-95%. The proportion of 29-34 wGA infants was significantly higher during the off-season compared to the in-season period (7% vs. 2.1%, p < 0.001). In a multivariable logistic regression model, the odds of hospitalization for 29-34 wGA preemies were 2.6 times higher during the off-season compared to the in-season (95% CI: 1.8-3.9, p < 0.001), independent of demographic covariates. Clinical severity was similar between the two periods.

CONCLUSIONS

Our results revealed a significantly higher proportion of 29-34 wGA infants hospitalized during seasons without palivizumab prophylaxis compared to seasons with palivizumab prophylaxis. These findings highlight the importance of including 29-34 wGA infants into future RSV immunoprophylaxis recommendations.

Development, Current Status, and Remaining Challenges for Respiratory Syncytial Virus Vaccines

Respiratory syncytial virus (RSV) causes significant morbidity and mortality, especially in young children and the elderly. RSV vaccine development puzzled vaccinologists for years. Safety concerns of initial formulations, the lack of an absolute correlate of protection, and the need for selecting appropriate virus attenuation and antigen-adjuvant combinations contributed to delayed vaccine production. The recent stabilization of the RSV-F glycoprotein in the prefusion (preF) conformation that constitutes the primary target of RSV-neutralizing antibodies was key for efficient vaccine design. Two protein subunit vaccines (GSK's Arexvy and Pfizer's Abrysvo) and one mRNA RSV vaccine (Moderna's mRESVIA) are now available. This article aims to provide a comparative overview of the safety and efficacy of novel RSV vaccines that are approved for the prevention of RSV-lower respiratory tract disease (LRTD) in adults 60 years of age and older, with updated recommendations calling for the expansion of vaccination to all adults at increased risk for severe RSV disease. Abrysvo is the only vaccine indicated for use in pregnancy to prevent RSV-LRTD in infants from birth to 6 months of age. We provide a comparative assessment of the efficacy of approved RSV vaccines over a maximum of three seasons, summarizing currently available data. We conclude that despite the decreasing vaccine efficacy over time, which should be anticipated for a virus that is characterized by short-term immunity, efficacy was clinically meaningful over placebo. The increased risk of Guillain-Barré syndrome post vaccination with Abrysvo or Arexvy, which prompted the FDA to require the inclusion of such warnings in the prescribing information of these two RSV vaccines, should be prioritized and investigated thoroughly. Furthermore, ongoing vaccine surveillance and further evaluation, particularly among immunocompromised patients, frail elderly subjects, and young infants that were under- or not represented in pivotal clinical trials, are necessary. As in the success story of combined pediatric vaccines, combination vaccines, conferring protection against several respiratory illnesses in one dose, could help improve vaccine acceptance and coverage rates in older adults.

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

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

Risk factors for severe disease in pediatric respiratory syncytial virus infections

OBJECTIVES

To assess factors associated with the risk of severe disease in children aged 5 years or younger with laboratory-confirmed respiratory syncytial virus (RSV) infection.

STUDY DESIGN

We conducted a nationwide retrospective cohort study in Mexico.

METHODS

Eligible participants included children aged 5 years or younger with laboratory-confirmed RSV infection January 1, 2023, and May 15, 2024. We collected relevant clinical and epidemiological data. Risk ratios (RR) and 95% confidence intervals (CI) were employed to identify factors associated with the risk of severe disease, characterized by clinical and radiographic evidence of bronchiolitis or pneumonia requiring hospital admission.

RESULTS

Data from 2022 children were analyzed and the overall risk of severe disease was 21.0% (n = 424/2022). In multiple generalized linear regression analysis, a personal history of immunosuppression (due to any cause) showed a protective effect (RR = 0.14, 95% CI 0.05-0.42, P = 0.001) against severe RSV disease, while an increased risk was documented for each additional day elapsed between the date of symptom onset and the date of seeking healthcare RR = 1.06, 95% CI 1.02-1.10, P = 0.004).

CONCLUSION

These findings provide insights into risk stratification and suggest specific directions for future research. This information informs the development of targeted intervention strategies to mitigate the impact of RSV infections in this vulnerable population.

Recent Progress toward the Discovery of Small Molecules as Novel Anti-Respiratory Syncytial Virus Agents

Respiratory syncytial virus (RSV) stands as the foremost cause of infant hospitalization globally, ranking second only to malaria in terms of infant mortality. Although three vaccines have recently been approved for the prophylaxis of adults aged 60 and above, and pregnant women, there is currently no effective antiviral drug for treating RSV infections. The only preventive measure for infants at high risk of severe RSV disease is passive immunization through monoclonal antibodies. This Perspective offers an overview of the latest advancements in RSV drug discovery of small molecule antivirals, with particular focus on the promising findings from agents targeting the fusion and polymerase proteins. A comprehensive reflection on the current state of RSV research is also given, drawing inspiration from the lessons gleaned from HCV and HIV, while also considering the impact of the recent approval of the three vaccines.

Occurrence of Central Nervous System Complications of Respiratory Syncytial Virus Infections: A Systematic Review with Meta-Analysis

An increasing base of evidence suggests that respiratory syncytial virus (RSV) infections may be associated with neurological complications. In accord with the PRISMA statement, we performed a systematic review and meta-analysis on the occurrence of encephalitis and encephalopathy associated with documented RSV infections. PubMed, Embase, and Scopus databases were searched for eligible observational studies published up to 10 April 2024. Raw data included the occurrence of RSV infections among cases of encephalitis and/or encephalopathy and cases of encephalitis and/or encephalopathy among series of RSV infections. Data were pooled in a random effects model. Case reports were also collected, and their data pooled as a cumulative series. Heterogeneity was assessed using the I2 measure, while reporting bias was assessed by means of funnel plots and regression analysis. A total of 15 studies for a total of 7719 RSV infections and 1631 cases of encephalitis were analyzed. Moreover, 27 case reports and case series were retrieved, for a total of 84 individual cases of encephalitis/encephalopathy occurring during a documented RSV infection. A pooled prevalence of 2.20 cases of encephalitis/encephalopathy per 100 RSV cases (I2 = 99%) was calculated, while a prevalence of RSV infections among cases of encephalitis/encephalopathy was estimated to 3.53 per 100 cases for studies on respiratory specimens (I2 = 48%) and 0.37 per cases on central nervous system (CNS) specimens (I2 = 0%). Detection of RSV within the CNS was relatively rare (17.86% of pooled case reports), being associated with male gender (adjusted odds ratio [aOR] 5.021, 95% confidence interval [95%CI] 1.104 to 22.831) and recovery with long-term sequelae (aOR 5.699, 95%CI 1.152; 28.183). Case fatality ratio was estimated to be 0.43 per 100 cases on observational studies and 10.71% in case reports, a difference likely due to publication bias. In summary, RSV represented a not frequent but notable cause of encephalitis/encephalopathy in adults and children. The paucity of available studies not only recommends a cautious appraisal of our results but stresses the clinical significance of future studies on incident cases of encephalitis and/or encephalopathy.

Impact of Nirsevimab Immunization on Pediatric Hospitalization Rates: A Systematic Review and Meta-Analysis (2024)

A systematic review with a meta-analysis was performed to gather available evidence on the effectiveness of monoclonal antibody nirsevimab in the prevention of lower respiratory tract diseases (LRTDs) due to respiratory syncytial virus (RSV) in children and newborns (CRD42024540669). Studies reporting on real-world experience and randomized controlled trials (RCTs) were searched for in three databases (PubMed, Embase, and Scopus) until 1 May 2024. Our analysis included five RCTs, seven real-world reports, and one official report from the health authorities. Due to the cross-reporting of RCTs and the inclusion of multiple series in a single study, the meta-analysis was performed on 45,238 infants from 19 series. The meta-analysis documented a pooled immunization efficacy of 88.40% (95% confidence interval (95% CI) from 84.70 to 91.21) on the occurrence of hospital admission due to RSV, with moderate heterogeneity (I2 24.3%, 95% CI 0.0 to 56.6). Immunization efficacy decreased with the overall length of the observation time (Spearman's r = -0.546, p = 0.016), and the risk of breakthrough infections was substantially greater in studies with observation times ≥150 days compared to studies lasting <150 days (risk ratio 2.170, 95% CI 1.860 to 2.532). However, the effect of observation time in meta-regression analysis was conflicting (β = 0.001, 95% CI -0.001 to 0.002; p = 0.092). In conclusion, the delivery of nirsevimab was quite effective in preventing hospital admissions due to LRTDs. However, further analyses of the whole RSV season are required before tailoring specific public health interventions.