Nirsevimab Sharply Cuts Rsv Hospitalizations In U.s. Infants During The 2024–2025 Season

Real-world information corroborate that nirsevimab provides powerful protection for infants, reducing RSV infirmary stays and easing nan strain connected families and healthcare systems.

Research letter: Nirsevimab Administration and RSV Hospitalization successful nan 2024-2025 Season. Image Credit: Bonn_A  / Shutterstock

In a caller Research Letter published successful the JAMA Network Open, a group of researchers estimated whether nirsevimab, a long-acting monoclonal antibody, lowers respiratory syncytial microorganism (RSV)-associated hospitalization among United States (US) infants during nan 2024-2025 play utilizing an extended physics wellness grounds (EHR) cohort.

Background

One microorganism fills wintertime pediatric wards: RSV is among nan starring reasons infants onshore successful nan hospital, particularly those calved prematurely, pinch analyzable conditions, aliases from communities facing socioeconomic disadvantage. Public wellness agencies successful nan US urge passive immunization of astir infants pinch nirsevimab, but families still ask: does it genuinely construe to less infirmary stays wherever we live? Real-world information matter because supplier supply, maternal vaccination, and session entree alteration by spot and season. Clinicians request precise numbers to guideline counseling, and parents request assurance erstwhile choosing prevention earlier nan first cough. Further investigation is required successful bid to analyse outcomes crossed divers wellness systems and subgroups.

About nan study

The investigators performed a retrospective cohort study utilizing nan Epic Systems Cosmos dataset, an EHR aggregation level that spans much than 300 cardinal patients crossed complete 1,700 hospitals and 40,000 clinics successful each 50 states, arsenic good arsenic successful Canada, Lebanon, and Saudi Arabia. The study included babies calved betwixt February 1, 2024, and January 31, 2025, ensuring astatine slightest 2 months of vulnerability to nan 2024-2025 RSV season, which typically occurs from October 1, 2024, to March 31, 2025. Infants aged 8 to 19 months were excluded owed to information granularity issues. The vulnerability was receipt of nirsevimab, nan superior result was RSV-associated hospitalization, identified utilizing validated International Classification of Diseases, Tenth Revision (ICD-10) algorithms.

The study excluded infants pinch missing maternal linkage, maternal RSV vaccination 14-280 days pre-delivery, pinch this removal accordant pinch CDC recommendations, anterior nirsevimab earlier April 1, 2024, RSV hospitalization earlier April 1, 2024, decease without hospitalization, aliases nary well-child visits aft September 30, 2025, to limit nonaccomplishment to follow-up. Group comparisons utilized two-sided Wilcoxon rank-sum tests for continuous variables and Pearson χ² tests for categorical variables. Daily hospitalization rates were modeled pinch generalized additive models (GAMs). Time-to-event analyses employed multistate Cox proportional hazards (Cox PH) models to modulation infants from untreated to treated connected nan nirsevimab date, pinch adjustments for chronologic age, gestational age, Social Vulnerability Index (SVI), and analyzable chronic conditions (CCC: cardiovascular, respiratory, and neurologic). Analyses were performed successful R (R Project for Statistical Computing) type 4.5.0.

Study results

Among 798,470 eligible births, 409,723 infants met inclusion criteria aft exclusions for missing maternal accusation (n=256,494), maternal RSV vaccination (n=75,107), decease (n=472), anterior nirsevimab (n=11,946), anterior RSV hospitalization (n=73), and deficiency of well-child follow-up aft September 30, 2025 (n=44,655). The median (interquartile range) property astatine study was 8 (5-10) months, and 51.1% of nan participants were male. Overall, 194,422 infants (47.5%) received nirsevimab, while 215,301 did not. Baseline array comparisons revealed mini but statistically important differences successful respective characteristics, including a somewhat younger property among treated infants and a higher prevalence of cardiovascular and neurologic analyzable chronic conditions successful nan treated group. The median gestational property was akin astatine 39 weeks crossed groups. The median SVI was 67 (IQR, 38–87), pinch immoderate missing values.

Nirsevimab receipt was associated pinch a markedly little crude complaint of RSV-associated hospitalization. Specifically, 850 of 194,422 treated infants (0.4%) were hospitalized compared pinch 2,535 of 215,301 untreated infants (1.2%), P<.001. Modeled regular hospitalization rates peaked astatine an estimated 2.90 (95% assurance interval [CI], 2.42-3.38) per 100,000 among treated infants versus 13.84 (95% CI, 13.16-14.53) per 100,000 among untreated infants during nan season.

Time-to-event analyses yielded accordant effect estimates. In unadjusted Cox PH models, nan hazard ratio (HR) for RSV-associated hospitalization aft nirsevimab curen was 0.29 (95% CI, 0.26-0.32). After adjusting for chronologic age, gestational age, SVI, and CCC categories (cardiovascular, respiratory, neurologic), nan HR was 0.23 (95% CI, 0.21-0.26), indicating an astir 77% little instantaneous consequence of hospitalization pursuing treatment. Multistate modeling that transitioned infants from untreated to treated connected nan management day supported nan temporal narration betwixt vulnerability and outcome.

Secondary utilization outcomes followed nan aforesaid direction. Intensive attraction portion (ICU) admissions attributed to RSV occurred successful 324 treated infants (0.2%) versus 765 untreated infants (0.4%), P<.001. Intubation was uncommon but little predominant among treated infants (49 vs. 90, some <0.1%, P = 0.004). The seasonal fig further illustrates nan rising cumulative sum of nirsevimab crossed autumn and winter, alongside consistently little modeled hospitalization rates successful nan treated cohort.

The researchers noted imaginable biases that could attenuate nan observed effectiveness, including nan incomplete seizure of maternal RSV vaccination position and nan imaginable receipt of nirsevimab extracurricular contributing wellness systems, which would misclassify vulnerability and bias nan results toward nan null. Restricting to infants pinch documented well-child attraction during nan play aimed to trim nonaccomplishment to follow-up. Overall, nan ample sample and consistency pinch anterior play estimates fortify assurance successful generalizability.

Conclusions

In a large, multi-system EHR cohort from nan 2024-2025 RSV season, nirsevimab was associated pinch substantially less RSV-related hospitalizations successful US infants, pinch adjusted HRs adjacent 0.23 and little ICU use. For families, this translates to less frightening infirmary stays and little disruption to activity and caregiving. For clinicians and wellness systems, it supports ongoing efforts to connection nirsevimab early successful nan play and equitably crossed communities, including infants pinch analyzable chronic conditions.