Laura D. Zambrano, Centers for Disease Control and Prevention
Regina M. Simeone, Centers for Disease Control and Prevention
Margaret M. Newhams, Boston Children’s Hospital, Boston, MA
Amanda B. Payne, Centers for Disease Control and Prevention
Natasha B. Halasa, Vanderbilt University Medical Center, Nashville, TN
Amber O. Orzel-Lockwood, Boston Children's Hospital, Boston, MA
Jemima M. Calixte, Boston Children's Hospital, Boston, MA
Satoshi Kamidani, Emory University, Atlanta, GA
Hillary Crandall, University of Utah, Salt Lake City, UT
Melissa A. Cameron, University of California, San Diego, CA
Jennifer E. Schuster, Children's Mercy Kansas City, Kansas City, MO
Aline B. Maddux, University of Colorado, Aurora, Colorado
Kathleen Chiotos, Children’s Hospital of Philadelphia, Philadelphia, PA
Katherine Irby, Arkansas Children's Hospital, Little Rock, AR
Steven L. Shein, University Hospitals Rainbow Babies & Children's Hospital, Cleveland, OH
Mary Allen Staat, Cincinnati Children's Hospital Medical Center, Cincinnati, OH
Lora M. Martin, University of Mississippi Medical Center, Jackson, MS
Samina S. Bhumbra, Indiana University, Indianapolis, IN
Ryan A. Nofziger, Akron Children's Hospital, Akron, OH
Jigar C. Chauhan, Nemours Children’s Hospital, Wilmington, DE
Danielle M. Zerr, University of Washington, Seattle, WA
Shira J. Gertz, Cooperman Barnabas Medical Center, Livingston, NJ
Judith A. Guzman-Cottrill, Oregon Health and Science University, Portland, OR
Michele Kong, University of Alabama at Birmingham, Birmingham, AL
Janet R. Hume, University of Minnesota Masonic Children’s Hospital, Minneapolis, MN
Bria M. Coates, Ann and Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL
Kelly N. Michelson, Ann and Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL
Tamara T. Bradford, LSU Health Science Center - New OrleansFollow
et al

Document Type

Article

Publication Date

11-20-2025

Publication Title

Morbidity and Mortality Weekly Report

Abstract

Respiratory syncytial virus (RSV) is a leading cause of intensive care unit (ICU) admission and respiratory failure among infants (children aged < 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.

First Page

580

Last Page

588

PubMed ID

41348586

Volume

74

Issue

37

Comments

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Rights

Public Domain

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