Laura D. Zambrano, Regina M. Simeone, Margaret M. Newhams, Amanda B. Payne, Natasha Halasa, Amber O. Orzel-Lockwood, Jemima M. Calixte, Satoshi Kamidani, Hillary Crandall, Melissa A. Cameron, Jennifer E. Schuster, Aline B. Maddux, Kathleen Chiotos, Katherine Irby, Steven L. Shein, Mary Allen Staat, Lora Martin, Samina S. Bhumbra, Ryan A. Nofziger, Jigar Chauhan, Danielle M. Zerr, Shira J. Gertz, Judith A. Guzman‐Cottrill, Michele Kong, Janet R. Hume, Bria M. Coates, Kelly N. Michelson, Emily R. Levy, Tamara T. Bradford, Stephanie P. Schwartz, Tracie C. Walker, Melissa S. Stockwell, Austin Biggs, Alexander H. Hogan, Katherine Lindsey, Angela Campbell, Adrienne G. Randolph, Overcoming RSV Investigators, Overcoming RSV Investigators, Michele Kong, Meghan Murdock, Heather M. Kelley, Candice Colston, Katherine Irby, Ronald C. Sanders, Masson Yates, Ashlyn Madding, Melissa A. Cameron, Michael Henne, Aline B. Maddux, Ariana Valenzuela, Natasha Baig, Lexi Petruccelli, Rachel M. Greer, Heidi Sauceda, Frances Zorensky, Alexander H. Hogan, Katherine W. Herbst, Carlie Defelice, Gretchen Blume, Jigar Chauhan, Scott L. Weiss, Rebecca Clifford, Jenna Lapira, Satoshi Kamidani, Mark D. Gonzalez, Caroline Ciric, Jong-Ha C. Choi, Gabriella Ess, Anna K. Mitchell, Luis W Salazar, Janelle J. Spencer-Ramirez, Kelly N. Michelson, Bria M. Coates, Sarah Jae Wershil, Samina S. Bhumbra, Mary Stumpf, Tamara T. Bradford, Adrienne G. Randolph, Margaret M. Newhams, Amber O. Orzel-Lockwood, Jemima M. Calixte, Amira Toivonen, Callum Ackerman, Janet R. Hume, Emily R. Levy, Chloe A Schluttner, Carly R Crowley, Meredith Lora, Martin, Joseph M. Majure, Lacy Malloch, Maygan Martin, Jennifer E. Schuster, Berenice Marrufo, Allison Scott, Shira J. Gertz, Elizabeth Ricciardi, Melissa S. Stockwell, Celibell Vargas
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.
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.