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 last weekly report of influenza activity (from March 5, 2017 through March 11, 2017) in a printable format.


There were 59 cases of influenza (Philadelphia resident, positive by rapid test, PCR or culture, and hospitalized for = 24 hrs.) in Philadelphia during week 10. Among select hospital laboratories, influenza A percent positivity declined compared to the previous week. Influenza-like illnesses (ILI) at emergency departments (ED) declined while pediatric outpatient clinic ILI increased for week 10. There was 2 influenza outbreaks (= 1 case of laboratory confirmed influenza) in long-term care facilities for week 10, resulting in a total of 27 for the 2016-2017 flu season. Thirteen influenza-associated deaths have been reported for the season. No pediatric influenza-associated deaths have been reported.

Summary Table of Influenza and Influenza-like Illness Activity for Philadelphia

Surveillance Type Compared to Week of 02/26-03/04 Compared to 3 Year Seasonal* Mean
Hosp. ED Fever/flu visits -
Peds. Clinic ILI -
Laboratory Influenza Surveillance -
= Above 10% of comparison group
- = Equivalent to comparison group (-10% to +10%)
= Below 10% of comparison group

Philadelphia Hospitalized Influenza Cases By Age Group
October 1, 2016 - March 11, 2017

Philadelphia Hospital Influenza Cases by Age Group

Laboratory-based Surveillance for Influenza A: Philadelphia, 2013/2014 through 2016/2017 Seasons
Influenza-like illness at Philadelphia Emergency Departments and Pediatric Ambulatory Clinics, 2016-2017


Flu activity is widespread. Flu activity has declined, but still remains high in Pennsylvania for week 10. The highest flu activity was reported in the southeast region of the state. From 10/02/16 to 3/11/17, there were 55,595 flu cases (positive by rapid test, PCR, or culture). There were 44,669 (80.3%) Influenza A cases,10,709 (19.3%) Influenza B cases and 217 (0.4%) unknown cases. 474 cases made up the season-to-date influenza sub-typing results from state public health labs. Influenza A/H3 made up 88.4% of the positive cases followed by Influenza B/Victoria (5.9%) and other (5.7%). Six influenza-associated deaths were reported this week bringing the total count to 101 for the 2016-2017 flu season, including two pediatric influenza-associated deaths.

United States

Flu activity decreased, but remained elevated in the U.S. during week 10. The percentage of respiratory specimens that tested positive for influenza in clinical laboratories decreased. 27,105 specimens were tested at clinical laboratories and 4,967 (18.3%) specimens tested positive for influenza. 3,037(61.1%) specimens tested positive for Influenza A and 1,930 (38.9%) specimens tested positive for Influenza B, an increase from last week. 1,511 specimens were tested at public health labs and 727 (48.1%) specimens tested positive. There were 514 (70.7%) positive Influenza A specimens and 213 (29.3%) positive Influenza B specimens. Influenza A/H3 was the most frequently identified influenza virus that was reported by public health labs with 476 (92.6%) positive tests. No viruses were resistant to oseltamivir, zanamivir and peramivir. Five influenza-associated pediatric deaths were reported to CDC during week 9, bringing the total count to 53 for the 2016-2017 flu season. Between 10/01/16 and 3/11/17, a rate cumulative rate of 46.9 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. The proportion of people visiting their health care provider for influenza-like illness (ILI) was 3.7%, which is above the national baseline of 2.2%. Eighteen states experienced high ILI activity. Seven states experienced moderate ILI activity. New Jersey, Pennsylvania and four states experienced low ILI activity. Delaware and 19 other states experienced minimal ILI activity. Thirty-six states, including Delaware, New Jersey and Pennsylvania reported widespread influenza activity. Eleven states reported regional influenza activity. Washington, DC and three states reported local influenza activity. Delaware had 391 laboratory-confirmed cases of flu. New Jersey had 9 cases of Influenza A/H3N2 and 55 cases of Influenza B.  

Updated: 03/21/2017