Nirsevimab will sharply reduce RSV hospitalizations in US infants during the 2024-2025 season

Actual data confirms that Nirsevimab provides strong protection for babies, reduces stays at RSV hospitals, and reduces strain on families and health care systems.

Research Letter: Nircevimab management and RSV hospitalization for the 2024-2025 season. Image credit: bonn_a/shutterstock

A recent research letter published on Jama Network Opena group of researchers estimated whether nilsevimab, a long-acting monoclonal antibody, reduces respiratory syncytial virus (RSV) – Hospitalization related to between the US (We) Infants during the 2024-2025 season use extensive electronic health records (Ehr)cohort.

background

One virus fills the pediatric ward in winter: RSV This is one of the main reasons why infants land in hospitals, particularly in complex situations or from communities facing socioeconomic disadvantages. Public Health Agency of We I recommend passive vaccination for most infants with nilsevimab, but families still ask. Actual data is important as drug supply, maternal vaccinations, and clinic access varies depending on location and season. Clinicians need accurate numbers to guide counseling, and parents need confidence in choosing prevention before the first cough. Further research is needed to explore the results of diverse health systems and subgroups as a whole.

About the research

Investigators include Epic Systems Cosmos Dataset; Ehr A collective platform that spans more than 300 million patients across more than 1,700 hospitals and 40,000 clinics in all 50 provinces of Canada, Lebanon and Saudi Arabia. This study includes babies born between February 1, 2024 and January 31, 2025, ensuring at least two months of exposure to 2024-2025 RSV Usually, this occurs between October 1, 2024 and March 31, 2025. Infants between 8 and 19 months were excluded due to granularity issues of the data. The exposure was the receipt of nilsevimab, and the main outcome was RSV– 10th revision identified using a validated international disease classification (ICD-10)algorithm.

In this analysis, we excluded infants and maternals with missing maternal binding. RSV Vaccination 14-280 days prior delivery, consistent with this exclusion CDC Recommendations, before Nirsevimab before April 1, 2024 RSV Limited follow-up losses with hospitalization prior to April 1, 2024, death without hospitalization, or well visits after September 30, 2025. For group comparisons, we used the double-sided Wilcoxon rank sum test and the Pearson χ² test for the categorical variables for the continuous variables. Daily hospitalization rates were modeled with a generalized additive model (game). In the time-to-event analysis, we adopted a multi-state cox proportional hazard (Cox PH) Adjusting the model, time series, gestational age, and social vulnerability index to treat infants from untreated to Nirsevimab dates;all), and complex chronic conditions (CCC: cardiovascular, respiratory, neurological). The analysis was performed in R (R Project for Statistical Computing) version 4.5.0.

Research Results

Of the 798,470 eligible births, 409,723 infants excluded missing maternal information (n = 256,494), maternal RSV Vaccination (n = 75,107), death (n = 472), previous nilsevimab (n = 11,946), prior RSV Hospitalization (n = 73) and lack of follow-up for well children after September 30, 2025 (n = 44,655). Median (interquartile range) age at the time of analysis was 8 months, with 51.1% of participants being male. Overall, 194,422 infants (47.5%) received nilcevimab, while 215,301 did not. Comparisons of the baseline table revealed small but statistically significant differences in several characteristics, including slightly younger ages among treated infants and higher prevalence of chronic conditions of cardiovascular and neurological complexes in the treatment group. Median gestational age was similar across groups at 39 weeks. Median all There were several missing values ​​at 67 (IQR, 38–87).

The receipt for nirsevimab is RSV– Related hospitalization. Specifically, 850 (0.4%) of 194,422 treated infants were hospitalized compared to 215,301 untreated infants (1.2%), p <.001. Modeled daily hospitalization rate peaked at an estimated 2.90 (95% confidence interval) [CI]2.42-3.38) per 100,000 (95% CI, 13.16-14.53) among infants treated, 100,000 per 100,000 (95% CI, 13.16-14.53) is 100,000 per 100,000 among untreated infants during the season.

Time-to-event analysis provided consistent estimates of effect. Not adjusted Cox PH Model, hazard ratio (HR) for RSV– Hospitalization-related after Nirsevimab treatment was 0.29 (95% CI, 0.26-0.32). After adjusting age and pregnancy age, alland CCC Categories (cardiovascular, respiratory, neurological), HR It was 0.23 (95% CI, 0.21-0.26), indicating an approximately 77% lower instantaneous risk of hospitalization after treatment. Multistage modeling that transitioned from untreated to treated infants on the day of administration supported the temporal relationship between exposure and outcome.

The results of secondary use followed the same direction. Intensive care unit (ICU)Affiliated admissions RSV It occurred in 324 treated infants (0.2%) versus 765 untreated infants (0.4%), p <.001. Intubation was rare, but not frequent among treated infants (49 vs 90, both <0.1%, p = 0.004). Seasonal figures show an increase in cumulative cumulative coverage of nilcevimab over autumn and winter, as well as a consistently low modeled hospitalization rate for treated cohorts.

Researchers focused on potential biases that could attenuate observed effectiveness, including incomplete maternal capture. RSV Vaccination status and potential health systems for nilsevimab receipts will misclassify exposures and bias the results towards null. Limiting to infants documented during the season was intended to reduce follow-up losses. Overall, the large sample and consistency with previous season estimates enhance confidence in generalization.

Conclusion

Large multi-system Ehr Cohorts for 2024-2025 RSV In the season, nilsevimab was associated with significantly less RSV– Related hospitalizations We Adjusted infants HRS 0.23 or less ICU use. For families, this means fewer hospital stays and less confusion in work and caregiving. For clinicians and healthcare systems, we support our ongoing efforts to provide nilcevimab early in the season, and strive to be fair across our community, including infants with complex chronic conditions.