A new study to be published in iScience on December 19, 2025, demonstrates the power of campus-based genomic surveillance in predicting the emergence of a dominant influenza strain. Conducted by researchers at Arizona State University, the study analyzed 516 nasal swabs collected from the student health clinic during the 2022-2023 northern hemisphere influenza season, identifying 100 positive cases.
The research revealed that the A(H3N2) subtype, particularly the 3C.2a1b.2a.2a.3a.1 clade, dominated on campus, contrasting with national trends where the 3C.2a1b.2a.2b clade prevailed. This early campus dominance of 3C.2a1b.2a.2a.3a.1 foreshadowed its rise as the dominant H3 clade nationally in the 2023-2024 and 2024-2025 seasons. The study suggests that introductions from North America and Europe supported local transmission, highlighting the role of university settings as early indicators of viral evolution.
The team noted an earlier peak in campus cases in November 2022, four weeks before the national peak, followed by a sharp decline. Genetic analysis showed high sequence similarity among H3 and N2 segments, with the 3C.2a1b.2a.2a.3a.1 clade making up 62% of campus H3 sequences. Vaccine effectiveness was estimated at 0.13–0.48, aligning with national figures for the season.
This research underscores the value of genomic surveillance in dense, semi-closed environments like university campuses. By providing early insights into influenza diversity, it could enhance public health preparedness and inform vaccine strategies for future seasons. The findings were published as an open-access article, offering a critical resource for ongoing influenza monitoring.
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