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 February 5, 2017 through February 11, 2017) in a printable format.


There were 134 cases of influenza (Philadelphia resident, positive by rapid test, PCR or culture, and hospitalized for = 24 hrs.) in Philadelphia during week 6. Among select hospital laboratories, influenza A percent positivity increased compared with the previous week. Influenza-like illnesses at emergency departments and pediatric ambulatory clinics also increased for week 6. There were 2 influenza outbreaks (= 1 case of laboratory confirmed influenza) in long-term care facilities this week, resulting in a total of 17 for the 2016-2017 flu season. Six 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 01/29-02/04 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
September 1, 2016 - February 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 and continues to increase in Pennsylvania for week 6. The highest flu activity was reported in the southeast region of the state. From 10/02/16 to 2/11/17, there were 33,271 flu cases (positive by rapid test, PCR, or culture). There were 28,553 (85.8%) Influenza A cases, 4,592 (13.8%) Influenza B cases and 126 (0.4%) unknown cases. 342 cases made up the season-to-date influenza sub-typing results from state public health labs. Influenza A/H3 made up 81.5% of the positive cases followed by Influenza B/Victoria (6.7%), Influenza A (6.9%) and other (4.9%). Thirteen influenza-associated deaths were reported this week bringing the total count to 51 for the 2016-2017 flu season, including one pediatric influenza-associated death.

United States

Flu activity increased in the U.S. during week 6. The percentage of respiratory specimens that tested positive for influenza in clinical laboratories increased. 35,098 specimens were tested at clinical laboratories and 8,498 (24.2%) specimens tested positive for influenza. 7,079 (83.3%) specimens tested positive for Influenza A and 1,419 (16.7%) specimens tested positive for Influenza B. 2,918 specimens were tested at public health labs and 1,732 specimens tested positive. There were 1,528 (88.2%) positive Influenza A specimens and 204 (11.8%) positive Influenza B specimens. Influenza A/H3 was the most frequently identified influenza virus that was reported by public health labs with 1,430 (93.6%) positive tests. No viruses were resistant to oseltamivir, zanamivir and peramivir. Nine influenza-associated pediatric deaths were reported to CDC during week 6, bringing the total count to 29 for the 2016-2017 flu season. Six deaths were associated with Influenza A/H3, two were associated with Influenza A virus and one death can be attributed to Influenza B. Between 10/1/16 and 2/11/17, a rate of 29.4 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 5.2%, which is above the national baseline of 2.2%. New York City, New Jersey, Pennsylvania and 25 states experienced high ILI activity. Eight states experienced moderate ILI activity. Seven states experienced low ILI activity. Delaware and 8 states experienced minimal ILI activity. Forty-three states, including Delaware, New Jersey and Pennsylvania reported widespread influenza activity. Four states reported regional influenza activity. Washington, DC reported local influenza activity. Delaware had 238 laboratory-confirmed cases of flu. New Jersey had 57 cases of Influenza A/H3N2 and 22 cases of Influenza B.    

Updated: 02/21/2017