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2019/2020 Influenza Season Data

The Pennsylvania Department of Health monitors influenza activity throughout the year but ramps up surveillance activities in the fall and winter. The official influenza surveillance season starts with the 40th week of the year (typically around the beginning of October) and ends on the 20th week of the following year (in May). For the 2019-2020 season, the influenza surveillance season began on Sept. 29, 2019, and will run through May 16, 2020. Updated influenza activity data will be posted on this web page every Tuesday throughout the influenza surveillance season. These updates will provide a summary on:

  1. When and where influenza activity is occurring;
  2. Current trends in influenza as compared to previous seasons; and
  3. What types and subtypes of influenza viruses are currently circulating. 

It is important to note that the influenza case counts presented on this page are restricted to only those cases that have had a positive laboratory test for flu (by rapid test, DFA, PCR or culture) reported to the PADOH. These case counts represent only a fraction of the actual burden of illness due to influenza occurring in the commonwealth at any given time. This is because most persons with influenza do not go to the doctor or are not tested or reported. Influenza spread and severity varies widely from season to season. It is estimated that five to 20 percent (600,000 to 2,400,000) of Pennsylvanians get the flu each year, and 120 to 2,000 die from complications of influenza.

Flu Activity Code: WIDESPREAD (week 12 ending 3/21/2020)

*The flu activity code is a characterization of the geographic spread of influenza in Pennsylvania. It does not indicate how severe the influenza season is. Rather, it indicates how much of Pennsylvania is experiencing influenza activity. The level of activity is classified based on CDC definitions below, which are used by all 50 states to characterize influenza activity.

No Activity No laboratory-confirmed cases of influenza and no reported increase in the number of cases of ILI.
SPORADIC Small numbers of laboratory-confirmed influenza cases or a single laboratory-confirmed influenza outbreak has been reported, but there is no increase in cases of ILI
LOCAL Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in a single region of the state
REGIONAL Outbreaks of influenza or increases in ILI and recent laboratory confirmed influenza in at least two but less than half the regions of the state, with recent laboratory evidence of influenza in those regions
WIDESPREAD Outbreaks of influenza or increases in ILI cases and recent laboratory-confirmed influenza in at least half the regions of the state, with recent laboratory evidence of influenza in the state

Influenza surveillance data presented below reflect influenza activity during the time period referred to above. Data may change from week to week as numbers are adjusted for late reporting, misclassification of cases, and errors in classifying county or state of residence.

Pennsylvania Weekly Influenza Report
Summary:

  • Flu activity has decreased over the past few weeks but is still high.
  • Percent outpatient visits related to influenza like illness has increased over past few weeks in outpatient clinics and emergency departments.
  • The code for the geographic spread is ‘WIDESPREAD’ for week 12 that ended on 3/21/2020, which is the highest on a scale of five geographic spread levels
    influenza A(H1N1) pdm09 is the most detected flu virus, however Influenza B/Victoria, and A(H3N2) viruses cocirculate in the community. The predominant viruses vary by region of the state and age group
  • A total of 128,736 laboratory-confirmed influenza cases have been reported season to date. Confirmed reports were received from 67 Counties out of the 67 Counties.
  • A total of 3,153 flu associated hospitalizations and 100 flu associated deaths have been reported season-to-date, including one pediatric influenza associated mortality.

Confirmed Influenza Laboratory Tests Received by PA DOH Surveillance

Table 1. Influenza Cases (positive by rapid test, PCR, or culture) Reported in Pennsylvania, 9/29/2019 to 3/21/2020 (n=128,736) - Cases by County and Influenza Type¥  

CountyInfluenza Type ​ ​TOTAL
ABU**
County Not Reported1741734351
ADAMS699122301922
ALLEGHENY59376342126713546
ARMSTRONG2833330616
BEAVER114314762592878
BEDFORD1834230606
BERKS1569269234264
BLAIR552104101593
BRADFORD62170001321
BUCKS2027153703564
BUTLER65663101287
CAMBRIA698106501763
CAMERON1431045
CARBON4272890716
CENTRE863136402227
CHESTER2017167923698
CLARION1001090209
CLEARFIELD64163101272
CLINTON1911990390
COLUMBIA1351550290
CRAWFORD64393201575
CUMBERLAND1116152612643
DAUPHIN1410180113212
DELAWARE29482247335228
ELK2724410713
ERIE2168227404442
FAYETTE71086701577
FOREST6309
FRANKLIN5654180983
FULTON1771890366
GREENE2443140558
HUNTINGDON3023780680
INDIANA3824950877
JEFFERSON2784090687
JUNIATA96470143
LACKAWANNA1138106002198
LANCASTER1251151602767
LAWRENCE2662020468
LEBANON58166001241
LEHIGH232722401764743
LUZERNE1899181843721
LYCOMING78651801304
MCKEAN3172310548
MERCER3894240813
MIFFLIN24717911437
MONROE1014115602170
MONTGOMERY511142382529601
MONTOUR79590138
NORTHAMPTON2772263505407
NORTHUMBERLAND3784780856
PERRY2072650472
PHILADELPHIA4265330787580
PIKE1981900388
POTTER2083190527
SCHUYLKILL847135202199
SNYDER2212809510
SOMERSET2262482476
SULLIVAN1918037
SUSQUEHANNA1801410321
TIOGA1331780311
UNION2572070464
VENANGO92870179
WARREN3672310598
WASHINGTON1137121222351
WAYNE64268301325
WESTMORELAND1554204223598
WYOMING89590148
YORK17802778314589
All61224654452067128736



(*) Numbers smaller than 5 have been replaced with an asterisk

(¥) Influenza counts are provisional and may change as more information is received

(**)Test results may identify influenza Type A, influenza Type B, or influenza without specifying Type A or B. Some tests only give a positive or negative result and can-not identify influenza type.

Figure 1. Number of Pa. Influenza Cases by Week of First Report

 

Figure 2: Comparison of PA-NEDSS Influenza Cases (All Types) in Current Season to the Eight Previous Seasons

Figure 2: Comparison of PA-NEDSS Influenza Cases (All Types) in Current Season to the Eight Previous Seasons

Figure 3: Season-to-date Influenza Sub-Typing Results From State Public Health Lab (n=422) 


 
Table 2: Season-To-Date Influenza-Associated Deaths by Age

Age Influenza-associated Death
0-18 1
19-49 10
50-64 21
65 + 68
All 100

Syndromic Surveillance

The Pennsylvania Department of Health's syndromic surveillance system receives data on visits to emergency departments (EDs) from most hospitals in the state.  The system looks at the reason for visiting the ED and determines if ED visits were likely due to influenza-like illness (ILI). The graph displays ED visits due to ILI as a percentage of total ED visits. This provides yet another way for the Department of Health to monitor influenza and ILI in the state. 

Figure 4: season-to-date Influenza-Like Illness (ILI) Emergency Visits

Figure 4: season-to-date Influenza-Like Illness (ILI) Emergency Visits


Figure 5: season-to-date Influenza-Like Illness (ILI) Emergency Visits by community health districts  
Figure 5: season-to-date Influenza-Like Illness (ILI) Emergency Visits by community health districts

Figure 6: season-to-date Influenza-Like Illness (ILI) Emergency Visits by age groups

Figure 6: season-to-date Influenza-Like Illness (ILI) Emergency Visits by age groups

World Health Organization (WHO) and National Respiratory & Enteric Virus Surveillance System (NREVSS) Collaborating Laboratories

Thirteen clinical virology laboratories in Pa. are WHO and/or NREVSS collaborating laboratories for influenza surveillance.

These labs report weekly the number of respiratory specimens tested and the number positive for influenza types A and B to CDC. Some labs also report the influenza A subtype (H1 or H3) and influenza B lineage (Victoria or Yamagata). Because denominator data is provided, the weekly percentage of specimens testing positive for influenza is calculated.

Figure 7: Influenza Test Results Reported to the National Respiratory and Enteric Virus Surveillance System (NREVSS) Select Pennsylvania Laboratories, Season to date

World Health Organization (WHO) and National Respiratory & Enteric Virus Surveillance System (NREVSS) Collaborating Laboratories