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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 3 ending 1/18/2020)

*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 slightly over the past week.
  • The code for the geographic spread is ‘WIDESPREAD’ for week 3 that ended on 1/18/2020, which is the highest on a scale of five geographic spread levels
  • Influenza B/Victoria is the most detected flu virus, however influenza A(H1N1) pdm09, and A(H3N2) viruses cocirculate in the community. The predominant viruses vary by region of the state and age group
  • A total of 39,421 laboratory-confirmed influenza cases have been reported season to date. Confirmed reports were received from 67 Counties out of the 67 Counties.
  • Percent of outpatient visits associated with Influenza-Like Illness (ILI) has slightly decreased, however it is still above the state epidemic threshold.
  • A total of 836 flu associated hospitalizations and 24 flu associated deaths have been reported season-to-date

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 1/18/2020 (n=39,421) - Cases by County and Influenza Type¥  

CountyInfluenza TypeTOTAL
ABU**
County not reported37
46
1
84
ADAMS110
241
0
351
ALLEGHENY1015
5033
632
6680
ARMSTRONG34
193
0227
BEAVER203
1227
196
1626
BEDFORD52
302
0
354
BERKS
422
740
2
1164
BLAIR
115
638
0
753
BRADFORD
246
264
0
510
BUCKS
377
526
0
903
BUTLER
93
369
0
462
CAMBRIA
150
825
0
975
CAMERON3
2
0
5
CARBON
74
138
0
212
CENTRE
69
176
0
245
CHESTER
386
596
0
982
CLARION
23
42
0
65
CLEARFIELD
155
155
0
310
CLINTON
24
33
0
57
COLUMBIA
18
66
0
84
CRAWFORD
43
153
0
196
CUMBERLAND
171
327
0
498
DAUPHIN
245
438
0
683
DELAWARE
534
737
3
1274
ELK
28
78
0
106
ERIE
124
405
0
529
FAYETTE
55
576
0
631
FOREST
****
FRANKLIN104
92
0
196
FULTON
53
49
0
102
GREENE
23
272
0
295
HUNTINGDON
74
122
0
196
INDIANA
69
234
0
303
JEFFERSON
54
191
0
245
JUNIATA
21
10
0
42
LACKAWANNA
211
252
0
463
LANCASTER
258
407
0
665
LAWRENCE
22
76
0
98
LEBANON
92
186
0
278
LEHIGH
496
797
55
1348
LUZERNE
332
385
2
719
LYCOMING
167
82
0
249
MCKEAN
14
71
0
85
MERCER
33
200
0
233
MIFFLIN
48
33
0
81
MONROE
269
340
0
609
MONTGOMERY1099
1393
82
2574
MONTOUR
14
25
0
39
NORTHAMPTON
539
1176
0
1715
NORTHUMBERLAND93
152
0
254
PERRY
60
69
0
129
PHILADELPHIA
845
1638
0
2483
PIKE
72
53
0
125
POTTER
19
84
0
103
SCHUYLKILL
212
766
0
978
SNYDER
47
189
0
236
SOMERSET
25
169
2
196
SULLIVAN
*
*
*
*
SUSQUEHANNA
33
15
0
48
TIOGA
25
20
0
45
UNION
41
85
0
126
VENANGO
11
19
0
30
WARREN
38
30
0
68
WASHINGTON
189
1036
2
1227
WAYNE
148
174
0
322
WESTMORELAND
301
1513
0
1814
WYOMING
27
12
0
39
YORK
300
412
0
712
All11288
27156
977
39421

(*) 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=115) 


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

Age Influenza-associated Death
0-18 0
19-49 2
50-64 4
65 + 18
All 24

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