The Philadelphia Department of Public Health (PDPH) Division of Disease Control conducts weekly influenza surveillance using chief complaints from Emergency Departments, influenza-like illness visit data, laboratory-based surveillance and institutional surveillance during flu season. The results of this surveillance are posted here every Friday in the season.

Click here for more information on Influenza, including how and when to report a case and other disease guidance. 

Click here to download the 2017-2018 influenza season summary report in a printable format.

Click here to download the last weekly report of influenza activity (from Dec. 1, 2019 through Dec. 7, 2019) in a printable format.


Febrile/flu-like illnesses continued to increase among children ages 0-4 years. Thirty-eight positive specimens were reported from our sentinel hospital laboratory surveillance for influenza A and B during the same time period among the 6 participating laboratories, most of which (31) were influenza B. There were 10 reports of severe influenza (Philadelphia resident, positive by rapid test, PCR or culture, and hospitalized for = 24 hrs.) during this time frame, with 70% positive for Influenza B. There were no influenza outbreaks (= 1 case of laboratory confirmed influenza reported in a long term care facility) reported this week, with a total of 1 outbreak this season. No influenza-associated deaths have been reported.

Febrile/Flu-like Illnesses at Philadelphia Emergency Departments 2017-2018 Data Compared to 4 Year Historical Weekly Averages Laboratory-based Surveillance for Influenza A: Philadelphia, 2013/2014 through 2017/2018 Seasons

Laboratory-based Surveillance for Influenza A: Philadelphia, 2013/2014 through 2017/2018 Seasons


The Pennsylvania Department of Health (PADOH) has reported “widespread” influenza activity, which is defined by the CDC as outbreaks of laboratory-confirmed influenza or increases in influenza-like-illness in at least half of the state. From 9/29/19 to 12/07/19, there have been 4,424 laboratory confirmed cases of influenza (positive by rapid test, PCR, or culture). The majority of influenza throughout the state has been identified as influenza B (3,285 reports, 74.3%). Six influenza related deaths have been reported thus far this season. For more information, please visit:

United States

Widespread activity has increased to 23 states from 16, with higher ILI-activity in Southern states. The majority of specimens tested in clinical laboratories since week 40 have been positive for influenza B (2,353, 68.5%). CDC has antigenically characterized 16 B/Victoria and 18 A(H1N1) viruses and has found that 10 (62.5%) of B/Victoria and 18 (100%) of A(H1N1) viruses were antigenically similar to the cell-grown reference viruses in the current vaccine. Almost all (>99%) tested viruses show susceptibility to oseltamivir, zanamivir, baloxavir and peramivir. For more information, please visit:

Updated: 12/13/2019