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TOPLINE
In an emulated target trial, nirsevimab use was associated with reduced antibiotic prescribing among infants during their first respiratory syncytial virus (RSV) season, with reductions of more than 14% for acute respiratory tract infections (ARTIs), more than 40% for bronchiolitis, and nearly 70% for RSV-related hospitalizations.
METHODOLOGY
- Researchers emulated a target trial using electronic health record data from the Children’s Hospital of Philadelphia Primary Care Network to assess whether nirsevimab reduced antibiotic use for ARTIs in outpatient and inpatient settings.
- They included 15,341 infants (mean age, 3.5 months) born between April 1 and September 30 during the 2023-2024 and 2024-2025 RSV seasons with at least one primary care visit within 14 days of birth. RSV season was defined by the month when each emulated trial began and categorized as prepeak (October-November), peak (December-January), or postpeak (February-March).
- Researchers used a sequential trial design, with the study period divided into six monthly intervals, and compared outcomes among infants who received nirsevimab (n = 7413) and those who did not (n = 7928).
- Primary outcomes included time to first antibiotic prescription for outpatient ARTIs, outpatient bronchiolitis encounters, and RSV-related hospitalizations; nirsevimab effectiveness was calculated as 1 minus the risk ratio.
TAKEAWAY
- At 6 months of follow-up, nirsevimab administration was associated with a 14.4% reduction (95% CI, 7.8%-20.6%) in antibiotic prescribing for outpatient ARTIs compared with no nirsevimab.
- Nirsevimab reduced antibiotic prescribing by 40.3% for outpatient bronchiolitis (95% CI, 25.1%-52.5%) and by 69.4% for RSV-related hospitalizations (95% CI, 4.8%-90.1%).
- In exploratory secondary analyses, nirsevimab was associated with a 26.8% reduction (95% CI, 20.8%-32.4%) in antibiotic prescribing for acute otitis media and a 22.5% reduction (95% CI, 12.6%-31.3%) for viral respiratory infections.
IN PRACTICE
“Nirsevimab administration reduced antibiotic use for ARTIs across settings, highlighting its secondary importance as an effective tool for combating antibiotic overuse,” the authors wrote. “Increasing currently suboptimal rates of nirsevimab coverage among infants in their first year of life should be a priority not only to prevent the morbidity associated with RSV bronchiolitis but also to supplement existing antibiotic stewardship efforts,” they concluded.
SOURCE
This study was led by Mahaa M. Ahmed, MS, Children’s Hospital of Philadelphia, and Torsten Joerger, MD, University of Pennsylvania Perelman School of Medicine and Children’s Hospital of Philadelphia, both in Philadelphia. It was published online on August 6, 2026, in Clinical Infectious Diseases.
LIMITATIONS
The study was limited to a pediatric care network across Pennsylvania and New Jersey, which may limit its national generalizability. The retrospective design relied on data recorded in the electronic health record, creating the potential for misclassification of exposures and outcomes. The study could not adjust for unmeasured factors, such as healthcare use, which may have influenced the chances of receiving nirsevimab as well as having a medically attended visit.
DISCLOSURES
This research received support from the Infectious Diseases Society of America’s Grants for Emerging Researchers/Clinicians Mentorship program. The authors disclosed no relevant conflicts of interest.
This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.
