How severe was the 2025–26 season, when did it peak, what strain drove it, and how does it compare?
Percentage of outpatient visits for flu-like illness (ILI%), nationally — CDC FluView ILINet surveillance, Weeks 40–20.
Share of positive flu tests by type, from CDC clinical laboratory surveillance (national).
Latest activity level by HHS region at end of season. Regions with higher levels later into spring had more prolonged spread.