Influenza Vaccine Effectiveness Against Outpatient Acute Respiratory Illness With Laboratory-confirmed Influenza, United States, 2024–2025 Season
Clinical Infectious Diseases·
- DOI
- 10.1093/cid/ciag437
- PMID
- 42442752
- PMCID
- —
- OpenAlex
- W7168281405
- Study type
- Journal article
- Publisher
- Oxford University Press (OUP)
- Article type
- journal-article
- Integrity
- current
Why this research matters now
The study provides a U.S. outpatient VE estimate for the 2024–2025 season, indicating vaccination reduced the risk of outpatient medically attended influenza by roughly one-third despite the predominance of A(H1N1)pdm09 and A(H3N2) viruses.
Structured evidence summary
Research question
The study evaluated how well seasonal influenza vaccination reduced the risk of outpatient medically attended influenza during the 2024–2025 U.S. season, overall and by virus type and subtype.
Study design
A multicentre, test-negative vaccine effectiveness (VE) study enrolled outpatients aged ≥8 months with acute respiratory illness including cough; specimens underwent RT-PCR testing and VE was estimated using a test-negative design adjusting for age, site, underlying health status, and month of illness onset.
Population and setting
Outpatients aged ≥8 months presenting with acute respiratory illness including cough at outpatient clinics, urgent care clinics, and emergency departments across 7 U.S. states during the 2024–2025 season.
Main findings
Among 6,793 enrolled patients, 2,016 (30%) tested influenza-positive, predominantly A(H3N2) and A(H1N1)pdm09. Overall VE against any influenza was 33% (95% CI 24–41); 27% (95% CI 14–39) against A(H3N2), 37% (95% CI 24–48) against A(H1N1)pdm09, and 40% (95% CI 12–59) against B/Victoria. No statistically significant interaction was detected between current and prior season vaccination.
Public-health relevance
The study provides a U.S. outpatient VE estimate for the 2024–2025 season, indicating vaccination reduced the risk of outpatient medically attended influenza by roughly one-third despite the predominance of A(H1N1)pdm09 and A(H3N2) viruses.
Important limitations
The summary is limited to the supplied single-article abstract/metadata and requires the original paper for decision-grade interpretation; limitations not explicitly stated in the abstract cannot be reported here.
GIDS interpretation
This single peer-reviewed article, indexed under influenza, vaccination, and vaccine effectiveness for the United States, is discoverable as contextual evidence for 2024–2025 season VE; it is not linked here to any live surveillance signal.
Related GIDS surveillance
Literature context does not validate, explain, or change a surveillance signal. Exact and contextual relationships are shown separately.
Evidence relationships
This article has 8 auditable classifier relationships to diseases, places, topics, and study design.