tetano
Editor, Senior Moderator
Clin Infect Dis
. 2026 Sep 26:ciag540.
doi: 10.1093/cid/ciag540. Online ahead of print.
Nathaniel M Lewis 1 , Seana Cleary 1 2 , Elizabeth J Harker 1 , Basmah Safdar 3 , Adit A Ginde 4 , Ithan D Peltan 5 , Manjusha Gaglani 6 7 , Cristie Columbus 8 9 , Emily T Martin 10 , Adam S Lauring 11 , Jay S Steingrub 12 , David N Hager 13 , Amira Mohamed 14 , Nicholas J Johnson 15 , Akram Khan 16 , Abhijit Duggal 17 , Jennifer G Wilson 18 , Nida Qadir 19 , Laurence W Busse 20 , Jennie H Kwon 21 , Matthew C Exline 22 , Ivana A Vaughn 23 , Jarrod M Mosier 24 , Estelle S Harris 25 , Yuwei Zhu 26 , Carlos G Grijalva 27 , Natasha B Halasa 28 , James Chappell 28 , Diya Surie 29 , Fatimah S Dawood 29 , Sascha Ellington 1 , Wesley H Self 30 ; Investigating Viruses in the Acutely Ill (IVY) Network
Collaborators, Affiliations
Background: The U.S. 2024-2025 influenza season was characterized by sustained elevated activity from November 2024-April 2025, with circulation of both influenza A(H1N1)pdm09 and A(H3N2), the latter of which included some antigenically drifted viruses.
Methods: From October 1, 2024, to April 30, 2025, a multistate respiratory virus surveillance network enrolled adults hospitalized with acute respiratory illness in 26 U.S. medical centers. Influenza vaccine effectiveness (VE) against influenza-associated hospitalization and severe in-hospital outcomes was estimated using a test-negative study. The odds of influenza vaccination among influenza-positive case patients and influenza-negative control patients were compared using multivariable logistic regression; VE was calculated as (1 - adjusted odds ratio for vaccination) × 100, expressed as a percent.
Results: The 2024-2025 seasonal influenza vaccine was effective against influenza-associated hospitalization (VE: 40% [95% confidence interval (CI): 32%-47%]), consistent across age group and influenza type/A subtype. Influenza vaccination also reduced the overall risk of all severe in-hospital outcomes evaluated, including standard oxygen therapy (VE: 41% [95% CI: 31%-50%]), non-invasive advanced respiratory support (VE: 38% [95% CI: 19%-52%]), invasive organ support (VE: 58% [95% CI: 44%-69%]), ICU admission (VE: 58% [95% CI: 47%-67%]), and death (VE: 52% [95% CI: 18%-71%]) with effectiveness varying by influenza A subtype and age.
Conclusions: Influenza vaccination reduced the risk of influenza-related hospitalization and severe in-hospital outcomes in adults during the severe 2024-2025 influenza season compared with those not vaccinated.
. 2026 Sep 26:ciag540.
doi: 10.1093/cid/ciag540. Online ahead of print.
Influenza vaccine effectiveness against influenza A-associated hospitalization and severe in-hospital outcomes among adults in the United States, 2024-2025
Nathaniel M Lewis 1 , Seana Cleary 1 2 , Elizabeth J Harker 1 , Basmah Safdar 3 , Adit A Ginde 4 , Ithan D Peltan 5 , Manjusha Gaglani 6 7 , Cristie Columbus 8 9 , Emily T Martin 10 , Adam S Lauring 11 , Jay S Steingrub 12 , David N Hager 13 , Amira Mohamed 14 , Nicholas J Johnson 15 , Akram Khan 16 , Abhijit Duggal 17 , Jennifer G Wilson 18 , Nida Qadir 19 , Laurence W Busse 20 , Jennie H Kwon 21 , Matthew C Exline 22 , Ivana A Vaughn 23 , Jarrod M Mosier 24 , Estelle S Harris 25 , Yuwei Zhu 26 , Carlos G Grijalva 27 , Natasha B Halasa 28 , James Chappell 28 , Diya Surie 29 , Fatimah S Dawood 29 , Sascha Ellington 1 , Wesley H Self 30 ; Investigating Viruses in the Acutely Ill (IVY) Network
Collaborators, Affiliations
- PMID: 42790883
- DOI: 10.1093/cid/ciag540
Abstract
Background: The U.S. 2024-2025 influenza season was characterized by sustained elevated activity from November 2024-April 2025, with circulation of both influenza A(H1N1)pdm09 and A(H3N2), the latter of which included some antigenically drifted viruses.
Methods: From October 1, 2024, to April 30, 2025, a multistate respiratory virus surveillance network enrolled adults hospitalized with acute respiratory illness in 26 U.S. medical centers. Influenza vaccine effectiveness (VE) against influenza-associated hospitalization and severe in-hospital outcomes was estimated using a test-negative study. The odds of influenza vaccination among influenza-positive case patients and influenza-negative control patients were compared using multivariable logistic regression; VE was calculated as (1 - adjusted odds ratio for vaccination) × 100, expressed as a percent.
Results: The 2024-2025 seasonal influenza vaccine was effective against influenza-associated hospitalization (VE: 40% [95% confidence interval (CI): 32%-47%]), consistent across age group and influenza type/A subtype. Influenza vaccination also reduced the overall risk of all severe in-hospital outcomes evaluated, including standard oxygen therapy (VE: 41% [95% CI: 31%-50%]), non-invasive advanced respiratory support (VE: 38% [95% CI: 19%-52%]), invasive organ support (VE: 58% [95% CI: 44%-69%]), ICU admission (VE: 58% [95% CI: 47%-67%]), and death (VE: 52% [95% CI: 18%-71%]) with effectiveness varying by influenza A subtype and age.
Conclusions: Influenza vaccination reduced the risk of influenza-related hospitalization and severe in-hospital outcomes in adults during the severe 2024-2025 influenza season compared with those not vaccinated.