Effectiveness of Palivizumab Against Respiratory Syncytial Virus Hospitalization Among Preterm Infants in a Setting With Year-Round Circulation

Impact of Palivizumab in Preventing Severe Acute Lower Respiratory Infection in Moderate-to-Late Preterm Infants: A Nationwide Cohort Study

BACKGROUND

Respiratory syncytial virus (RSV) prophylaxis using palivizumab effectively reduces RSV-associated morbidity in preterm infants. In Korea, national insurance coverage for palivizumab was implemented in October 2016 for moderate-to-late preterm (MLPT) infants born during the RSV season (October-March) who have older siblings. However, no large-scale studies have investigated the changes in the incidence and risk of severe acute lower respiratory infections (ALRIs) after insurance coverage implementation for MLPT infants.

METHODS

This large-scale retrospective cohort study used data from the Korean National Health Insurance Service between October 2013 and December 2019. MLPT infants (32 0/7-35 6/7 weeks of gestation) with older siblings were stratified into pre-insurance period (PIP; October 2013-September 2016) and insurance period (IP; October 2016-March 2019) groups based on the date of birth with respect to initial insurance palivizumab implementation. Severe ALRI outcomes (hospitalization, respiratory support, and intensive care unit admission) were evaluated up to 1 year of age using multivariable logistic regression models.

RESULTS

Of the 11,722 MLPT infants included in the study, 6,716 and 5,006 infants were included in the IP and PIP groups, respectively. The incidences of ALRI-hospitalization and ALRI-respiratory support were significantly lower in the IP group than that in PIP group (24.0% vs. 26.0% and 3.1% vs. 4.0%, respectively). Additionally, ALRI-respiratory support risk was significantly lower in the IP group (adjusted odds ratio 0.771, 95% confidence interval 0.626-0.949, P = 0.014) than that in the PIP group. Among infants born during the RSV season, the risk of ALRI-hospitalization and ALRI-respiratory support were significantly lower in the IP group than that in the PIP group. However, no significant differences were observed between the IP and PIP groups for infants born during the non-RSV season.

CONCLUSION

The risks of severe ALRI outcomes decreased in Korea following the 2016 insurance implementation of palivizumab prophylaxis for MLPT infants born during the RSV season with older siblings.

Nirsevimab: Alleviating the burden of RSV morbidity in young children

Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infections (LRTIs) and hospital admissions in early childhood. Recent advancements in novel preventive therapies, including extended half-life monoclonal antibodies and antenatal vaccination, have afforded new opportunities to significantly reduce the burden of this infection. Nirsevimab is a novel monoclonal antibody that provides sustained protection against RSV for at least 5 months among newborns and young children. It has received regulatory approval in numerous countries and is being implemented across various settings. Two pivotal Phase 3 trials (MELODY, HARMONIE) demonstrated significant reductions in RSV-associated LRTI hospitalisations following nirsevimab administration, with treatment efficacy of 62.1% and 83.2%. Emerging real-world data from early adopters of nirsevimab corroborates these findings. Studies from Spain, Luxembourg, France and the USA report effectiveness rates between 82% and 90% in preventing RSV-associated hospitalisations among infants entering their first RSV season. Current implementation strategies for nirsevimab have primarily focused on seasonal administration for all infants, aligned to local RSV seasons, and often include catch-up doses for those born before the season begins. Available cost-effectiveness analyses indicate that while nirsevimab offers significant potential public health benefits, its adoption must carefully consider economic factors such as treatment costs, implementation strategies tailored to local viral epidemiology, and logistics for vaccine delivery. Overall, nirsevimab presents a promising opportunity to alleviate the burden of severe RSV infections in young children. However, ongoing surveillance and refinements in implementation strategies are crucial to optimise its impact and ensure sustainability across diverse health-care settings.

Effectiveness and Safety of Palivizumab for the Prevention of Serious Lower Respiratory Tract Infection Caused by Respiratory Syncytial Virus: A Systematic Review

OBJECTIVE

Palivizumab is a humanized monoclonal antibody approved for the prevention of serious lower respiratory tract infection (LRTI) caused by respiratory syncytial virus (RSV) in infants and young children at high risk of RSV disease. This systematic review summarized evidence on the effectiveness and safety of palivizumab when used in approved populations.

STUDY DESIGN

A systematic review of Phase III trials and observational studies was conducted according to the population, intervention, comparator, outcome, timing, setting (PICOTS) approach (PROSPERO, CRD42021281380). Target populations consisted of infants with a history of premature birth (≤35-week gestational age) and children aged <2 years with bronchopulmonary dysplasia (BPD) or with hemodynamically significant congenital heart disease (hs-CHD). Outcomes of interest included RSV-related hospitalization, admission to intensive care unit (ICU), requirement for mechanical ventilation, treatment-related adverse events (AEs), and RSV-related deaths. Information sources were literature search (Ovid MEDLINE and Embase), pragmatic searches, and snowballing (covering the period up to 07 September 2021).

RESULTS

A total of 60 sources were included (5 Phase III trials and 55 observational studies). RSV-related hospitalization rates following palivizumab prophylaxis in Phase III trials were 1.8% in premature infants and 7.9% in children with BPD, which were significantly lower than rates in placebo arms. In the real-world setting, similar hospitalization rates were found (0.7-4.0% in premature infants [16 studies] and 0-5.5% in patients with BPD [10 studies]) with ICU admission reported in 0 to 33.3% of patients hospitalized for RSV. In Phase III trials, RSV-related mortality rates were 0.2 and 0.3%, while AEs occurred in 11% of premature and/or BPD patients and 7.2% of hs-CHD patients, consisting mainly of injection site reaction, fever, and diarrhea. Similar results were found in observational studies.

CONCLUSION

This systematic review supports the effectiveness and safety of palivizumab in the indicated populations.

KEY POINTS

· Systematic review supports the positive benefit-risk profile of palivizumab in the indicated populations.. · Real-world safety and effectiveness of palivizumab are consistent with Phase III trials results.. · Palivizumab reduces RSV-related hospitalizations, ICU admissions, and need for mechanical ventilation..

Efficacy and Safety of Palivizumab as a Prophylaxis for Respiratory Syncytial Virus (RSV) Disease: An Updated Systemic Review and Meta-Analysis

This systematic review and meta-analysis aimed to summarize the current evidence regarding the efficacy and safety of palivizumab as a prophylaxis for respiratory syncytial virus (RSV) disease. We searched MEDLINE via PubMed, Scopus, Cochrane, Web of Science, Embase, and Science Direct from inception till November 2023. Studies that assessed the efficacy and safety of palivizumab in infants aged between 28 days and three months of age were included. We analyzed the data using Review Manager 5.4 software, with results pooled across studies and expressed as risk ratios (RR) with 95% confidence intervals (CI). A total of 10 studies were included. The effect estimates favored palivizumab over placebo regarding the hospitalization for RSV infection (RR=0.51, 95% CI: 0.40 to 0.65; P<0.00001) and ICU admission (RR=0.49, 95% CI: 0.30 to 0.81; P=0.005). On the other hand, the effect estimate showed no significant difference between palivizumab and placebo regarding all-cause mortality (RR=0.69, 95% CI: 0.42 to 1.15; P=0.16), lower respiratory tract infection (RR=0.42, 95% CI: 0.11 to 1.69; P=0.22), and need for mechanical ventilation (RR=0.75, 95% CI: 0.34 to 1.67; P=0.48). Palivizumab can be considered a prophylaxis for RSV disease in young children as it is safe, well-tolerated, and effective in reducing RSV hospitalizations. However, further research through high-quality randomized controlled trials is required to determine its efficacy as a therapeutic agent for established RSV infections.

Respiratory syncytial virus: from pathogenesis to potential therapeutic strategies

Respiratory syncytial virus (RSV) is one of the most important viral pathogens causing respiratory tract infection in infants, the elderly and people with poor immune function, which causes a huge disease burden worldwide every year. It has been more than 60 years since RSV was discovered, and the palivizumab monoclonal antibody, the only approved specific treatment, is limited to use for passive immunoprophylaxis in high-risk infants; no other intervention has been approved to date. However, in the past decade, substantial progress has been made in characterizing the structure and function of RSV components, their interactions with host surface molecules, and the host innate and adaptive immune response to infection. In addition, basic and important findings have also piqued widespread interest among researchers and pharmaceutical companies searching for effective interventions for RSV infection. A large number of promising monoclonal antibodies and inhibitors have been screened, and new vaccine candidates have been designed for clinical evaluation. In this review, we first briefly introduce the structural composition, host cell surface receptors and life cycle of RSV virions. Then, we discuss the latest findings related to the pathogenesis of RSV. We also focus on the latest clinical progress in the prevention and treatment of RSV infection through the development of monoclonal antibodies, vaccines and small-molecule inhibitors. Finally, we look forward to the prospects and challenges of future RSV research and clinical intervention.