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2019/2020 Influenza Season Data

Influenza activity has decreased significantly, so the Bureau of Epidemiology will stop updating this flu activity webpage and last posted report is for week 13 that ended on 28 March, 2020. The report will be updated when flu activity increases with the beginning of the next flu season.

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: LOCAL (week 13 ending 3/28/2020)

*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 and now is below epidemic limits.
  • Percent outpatient visits related to influenza like illness has decreased during past week in outpatient clinics and emergency departments.
  • The code for the geographic spread is ‘LOCAL’ for week 13 that ended on 3/28/2020, which is the third 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 129,912 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 3,226 flu associated hospitalizations and 102 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 3/28/2020 (n=129,912) - Cases by County and Influenza Type¥  

CountyInfluenza Type ​ ​TOTAL
ABU**
County Not Reported1761734353
ADAMS708123301941
ALLEGHENY60726354126813694
ARMSTRONG2853330618
BEAVER119014772592926
BEDFORD1844230607
BERKS1582270534290
BLAIR571104601617
BRADFORD62270001322
BUCKS2042154303585
BUTLER65963101290
CAMBRIA717106801785
CAMERON1431045
CARBON4352900725
CENTRE869136402233
CHESTER2055168743746
CLARION1081090217
CLEARFIELD64663301279
CLINTON1931990392
COLUMBIA1361550291
CRAWFORD64493201576
CUMBERLAND1125153112657
DAUPHIN1505183213338
DELAWARE29752251335259
ELK2744430717
ERIE2235228304518
FAYETTE72187601597
FOREST6309
FRANKLIN5664210987
FULTON1791910370
GREENE2443140558
HUNTINGDON3083810689
INDIANA3894960885
JEFFERSON2864090695
JUNIATA98470145
LACKAWANNA1162106412227
LANCASTER1264151902783
LAWRENCE2682020470
LEBANON58666001246
LEHIGH234322581934794
LUZERNE1917182353745
LYCOMING79152101312
MCKEAN3202320552
MERCER3964240820
MIFFLIN25017911440
MONROE1021115902180
MONTGOMERY515542432529650
MONTOUR79590138
NORTHAMPTON2794264005434
NORTHUMBERLAND3844800864
PERRY2072660473
PHILADELPHIA4296331587619
PIKE1981900388
POTTER2103220532
SCHUYLKILL855135502210
SNYDER2212809510
SOMERSET2302502482
SULLIVAN2118039
SUSQUEHANNA1831410324
TIOGA1381800318
UNION2642080472
VENANGO100870187
WARREN3862330619
WASHINGTON1150121522367
WAYNE65869601354
WESTMORELAND1584205023636
WYOMING90590149
YORK18032788314622
All62143656802089129912

(*) 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=423) 


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

Age Influenza-associated Death
0-18 1
19-49 10
50-64 21
65 + 70
All 102

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