Health Information Portal (HIP)

Philadelphia Influenza Surveillance Updates: PDPH tracks influenza activity in Philadelphia, especially severe influenza disease. Providers should report all hospitalized influenza cases, influenza deaths in children, and influenza outbreaks in closed settings like long-term care facilities and shelters.

Week 51: During week 51, influenza diagnoses at local emergency departments increased for all age groups. Positive detections for influenza A at select local hospital laboratories increased sharply, while detections for influenza B remained low but increased during week 51. Nine influenza outbreaks in long-term care facilities have been reported and confirmed (≥ 1 case of laboratory confirmed flu reported in a long-term care facility) during the 2025-2026 season to date.

Week 51 Report: Click here to download the latest weekly report of influenza activity (December 14, 2025—December 20, 2025) in a printable format.

State and National Influenza Surveillance Updates:

Pennsylvania: As of December 20, 2025, the Pennsylvania Department of Health (PADOH) respiratory virus summaries currently list influenza activity as moderate and increasing rapidly. Activity levels in PA are based on laboratory confirmed influenza cases. For more information, please visit: https://www.pa.gov/agencies/health/diseases-conditions/infectious-disease/respiratory-viruses/respiratory-virus-dashboard.

United States: As of December 20, 2025, the CDC reported that influenza activity is elevated and increasing across the country. In week 51, clinical laboratories reported 23,613 (25.6%) of 92,115 specimens tested positive for influenza, 94.7% of which were influenza A. Of influenza A specimens subtyped at public health labs, 84.8% have been subtyped as H3N2 and 15.2% have been subtyped as H1N1. In week 51, 14 jurisdictions with sufficient data reported minimal to low levels of activity, while 8 jurisdictions, including Pennsylvania, reported moderate activity. Additionally, 32 jurisdictions reported high to very high activity, including New York City, New York State, and New Jersey. Activity levels are calculated from outpatient data reported to ILINet. For more information, please visit: https://www.cdc.gov/fluview/surveillance/2025-week-51.html.