ArticleJAMA network open2026
Influenza Activity and Estimated Vaccine Effectiveness During the 2025-2026 Influenza Season.
Article in JAMA network open, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
2 citing papers in PubMed.
- Host cell entry and neutralisation sensitivity of H3N2 influenza A virus subclade K.NPJ vaccines · 2026Article
- mRNA-1010 and the Future of Seasonal Influenza Prevention: Towards Next-Generation Respiratory Vaccination.Vaccines · 2026Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
43 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Importance: Antigenically drifted influenza A(H3N2) J.2.4.1 (subclade K) viruses predominated during the 2025-2026 Northern Hemisphere influenza season. Objective: To describe influenza activity and burden, characterize subclade K, evaluate susceptibility to influenza antivirals and postinfluenza vaccination antibodies, and estimate vaccine effectiveness. Design, Setting, and Participants: This surveillance study used multiple data sources, including (1) national surveillance of influenza-positive respiratory specimens collected by approximately 300 clinical laboratories and 100 public health laboratories from October 1, 2025, through March 14, 2026, a subset of which were further characterized; (2) serologic data of people who received 2025-2026 influenza vaccines; (3) influenza admissions data from the Influenza Hospitalization Surveillance Network (ie, 10% of US population) and the associated estimates of US burden; and (4) test-negative, case-control vaccine effectiveness estimates from the Virtual SARS-CoV-2, Influenza, and Other Respiratory Viruses Network. Exposures: Influenza infection, hospitalization, and vaccination. Main Outcomes and Measures: Outcomes included influenza virus type, subtype, and clade; antiviral susceptibility; immunogenicity; influenza-associated outpatient and emergency department visits, hospitalizations, and mortality; estimated influenza illnesses, hospitalizations, and death; and estimated vaccine effectiveness. Results: As of March 14, 2026, of the 55 318 influenza-positive respiratory specimens tested by public health laboratories, most (50 291 specimens [90.9%]) were influenza A, of which 40 779 (81.1%) were subtyped and 35 801 (87.8%) were A(H3N2). Of the 1754 characterized A(H3N2) viruses, most (1626 specimens [92.7%]) were subclade K. Postinfluenza vaccination neutralizing geometric mean antibody titers against subclade K were reduced 1.62 (95% CI, 1.29-2.02)-fold compared with the vaccine virus. All 1729 tested A(H3N2) viruses were sensitive to antivirals. Of the 27 881 recorded influenza hospitalizations, 15 426 (54.7%) were among female patients, and 15 051 (54.0%) were among patients aged 65 years or older. The estimated cumulative influenza-associated hospitalization rate was 80.0 per 100 000 which would correlate with estimates of between 28 000 000 to 49 000 000 illnesses, 360 000 to 740 000 hospitalizations, and 22 000 to 74 000 deaths in the US during the 2025-2026 season. Adjusted interim vaccine effectiveness estimates against influenza-associated emergency department or urgent care encounters and hospitalizations were 35% (95% CI, 33%-38%) and 27% (95% CI, 21%-34%), respectively. Conclusions and Relevance: This surveillance study found that while antigenically drifted viruses predominated and caused substantial morbidity and mortality, influenza vaccines were associated with a reduced risk of influenza among those who were vaccinated, and recommended antivirals remained effective.
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