Document Type

Article

Publication Date

11-20-2025

Identifier

DOI: 10.15585/mmwr.mm7437a1

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.

Journal Title

MMWR. Morbidity and mortality weekly report

Volume

74

Issue

37

First Page

580

Last Page

588

MeSH Keywords

Humans; Respiratory Syncytial Virus Infections; Infant; United States; Antibodies, Monoclonal, Humanized; Case-Control Studies; Antiviral Agents; Male; Female; Intensive Care Units; Infant, Newborn; Hospitalization; Respiratory Insufficiency; Treatment Outcome; Patient Admission

PubMed ID

41348586

Keywords

Respiratory Syncytial Virus Infections; United States; Humanized Monoclonal Antibodies; Case-Control Studies; Antiviral Agents; Intensive Care Units; Hospitalization; Respiratory Insufficiency; Treatment Outcome; Patient Admission

Comments

The MMWR series of publications is published by the Center for Surveillance, Epidemiology, and Laboratory Services, Centers for Disease Control and Prevention (CDC), U.S. Department of Health and Human Service.

Download

Share

COinS