Nirsevimab Effectiveness Against Intensive Care Unit Admission for Respiratory Syncytial Virus in Infants - 24 States, December 2024-April 2025
- PMID: 41348586
- DOI: 10.15585/mmwr.mm7437a1
Nirsevimab Effectiveness Against Intensive Care Unit Admission for Respiratory Syncytial Virus in Infants - 24 States, December 2024-April 2025
Abstract
Respiratory syncytial virus (RSV) is a leading cause of intensive care unit (ICU) admission and respiratory failure among infants (children aged <1 year) in the United States. In August 2023, CDC's Advisory Committee on Immunization Practices recommended nirsevimab, a long-acting monoclonal antibody, to protect against RSV-associated lower respiratory tract infection among all infants aged <8 months born during or entering their first RSV season. Following licensure, nirsevimab effectiveness has been demonstrated against RSV-associated infant hospitalization, but evidence regarding effectiveness against RSV-associated critical illness is limited. In a 27-hospital case-control investigation, nirsevimab effectiveness against both RSV-associated infant ICU admission and acute respiratory failure (illness requiring continuous positive airway pressure, bilevel positive airway pressure, or invasive mechanical ventilation) after hospital admission was evaluated during December 1, 2024-April 15, 2025. Among 457 case-patients who received a positive RSV test result and 302 control patients who received a negative RSV test result admitted to an ICU with respiratory symptoms, 14% and 45%, respectively, had received nirsevimab ≥7 days before symptom onset. Nirsevimab was 80% effective (95% CI = 70%-86%) against RSV-associated ICU admission and 83% effective (95% CI = 74%-90%) against acute respiratory failure when received a median of 52 days (IQR = 32-89 days) and 50 days (IQR = 32-86 days) before onset for each respective endpoint. These estimates support the recommendation for use of nirsevimab as a prevention strategy to protect infants against severe outcomes from RSV infection.
Conflict of interest statement
All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Katherine Irby reports institutional support from the National Institutes of Health (NIH). Satoshi Kamidani reports institutional support from NIH, Pfizer, Moderna, Meissa, Bavarian Nordic, and Sanofi, and receipt of payment or honoraria from the American Academy of Pediatrics. Kelly N. Michelson reports institutional support from the Patient-Centered Outcomes Research Institute, NIH, the Greenwall Foundation, and Friends of Prentice; payment or honoraria from the University of Chicago; membership on the Normal Moments board; and is a cofounder of Missing Pieces, a program of the HAP foundation, and serves in an advisory position to that organization, from which she might receive future financial benefits related to her engagement with the program. Jennifer E. Schuster reports institutional support from NIH, the Food and Drug Administration, and the state of Missouri; receipt of consulting fees from the Association of professionals in Infection Control and Epidemiology; speaking honoraria from the Missouri American Academy of Pediatrics (AAP); and paid membership on the Association of American Medical Colleges Advisory Board for a grant awarded for vaccine confidence. Regina M. Simeone reports stock in Pfizer owned by her spouse, which was sold in April 2022. Mary Allen Staat reports institutional support from NIH, Merck, and Cepheid; receipt of royalties from UpToDate Inc.; and consulting fees from Merck. Melissa S. Stockwell reports receipt of support from subcontracts from Boston Children’s Hospital, Vanderbilt University (for RSV surveillance), and Westat (for vaccine effectiveness surveillance), and a service agreement from AAP, paid to trustees of Columbia University. Natasha B. Halasa reports receipt of grant support from Merck and receipt of consulting fees as a member of an advisory board for CSL-Seqirus. Hillary Crandall reports institutional support from the National Institute of General Medical Sciences, NIH and from Mortensen and Milne for expert testimony. Danielle M. Zerr reports institutional support from Merck and participation on endpoint adjudication committees for two Allovir trials. Michele Kong reports institutional support from NIH and uncompensated membership of the Jefferson County Health Department University of Alabama Callahan Board, KultureCity. Janet R. Hume reports institutional support from the National Institute for Allergy and Infectious Diseases (NIAID) and the National Institute of Child Health and Human Development, NIH, and unpaid service on a data safety monitoring board for an institutional study of magnesium sulfate as adjuvant analgesia and its effect on opiate use by postoperative transplant patients in the pediatric intensive care unit at the University of Minnesota. Bria M. Coates reports institutional support from NIAID and the National Heart, Lung, and Blood Institute, NIH. Adrienne G. Randolph reports institutional support from NIH and receipt for royalties from UpToDate, Inc. for section editor duties; consulting fees from Inotrem, Inc. and ThermoFisher, Inc.; honoraria from St. Jude Children’s Research Center and Volition, Inc.; travel or meeting support from the International Sepsis Forum; participation on a data safety monitoring board for NIH and Randomised, Embedded, Multi-factorial; Adaptive Platform Trial for Community-Acquired Pneumonia; service as chair of the International Sepsis Forum; and institutional receipt of equipment, materials, or other services from Illumina, Inc. No other potential conflicts of interest were disclosed.
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