Begin Main Content Area

2018/19 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 2018-2019 season, the influenza surveillance season began on Oct. 1, 2018, and will run through May 19, 2019. 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 16 ending 4/20/2019)

*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 continued to decrease during the past week in all state regions, and the activity is below the epidemic threshold for the first time since the beginning of the epidemic. Highest activity was reported in the Northwest region.

The code for the geographic spread is 'LOCAL' for week 16 that ended on 4/20/2019.

A total of 96,365 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 decreased and is below the epidemic threshold for all State regions.

There are 133 flu associated deaths reported season-to-date, including two pediatric influenza associated deaths.

Confirmed Influenza Laboratory Tests Received by PA DOH Surveillance

Table 1. Influenza Cases (positive by rapid test, PCR, or culture) Reported in Pennsylvania, 9/30/2018 to 4/20/2019 (n=96,365) - Cases by County and Influenza Type*   

COUNTYINFLUENZA TYPE ​ ​TOTAL
ABU**
COUNTY UNKNOWN20981218
ADAMS865120877
ALLEGHENY86752534169344
ARMSTRONG43380441
BEAVER1733141611908
BEDFORD330230353
BERKS36437313717
BLAIR12692701296
BRADFORD95090959
BUCKS27569712854
BUTLER11826421248
CAMBRIA10247441102
CAMERON915096
CARBON47342479
CENTRE167512801803
CHESTER28136612880
CLARION351166373
CLEARFIELD12452201267
CLINTON32280330
COLUMBIA536150551
CRAWFORD15412901570
CUMBERLAND17898901878
DAUPHIN17846321849
DELAWARE4691116784885
ELK77410775
ERIE23552002375
FAYETTE15606501625
FOREST160016
FRANKLIN648170665
FULTON28870295
GREENE38660392
HUNTINGDON471170488
INDIANA563400603
JEFFERSON928170945
JUNIATA11210113
LACKAWANNA1524291061659
LANCASTER22645912324
LAWRENCE52370530
LEBANON13037301376
LEHIGH3920891224131
LUZERNE30262803054
LYCOMING11433601179
MCKEAN50340507
MERCER586240610
MIFFLIN32623208557
MONROE10491901068
MONTGOMERY6278310856673
MONTOUR13010131
NORTHAMPTON321012983347
NORTHUMBERLAND92940933
PERRY292130305
PHILADELPHIA43737634452
PIKE23010231
POTTER543540597
SCHUYLKILL942141957
SNYDER416150431
SOMERSET313132328
SULLIVAN7007
SUSQUEHANNA21502217
TIOGA23720239
UNION215160231
VENANGO22010221
WARREN44800448
WASHINGTON19297332005
WAYNE7881010889
WESTMORELAND31908503275
WYOMING19520197
YORK25889802686
All923362813121696365


* 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 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=636) 

Figure 3: Season-to-date Influenza Sub-Typing Results From State Public Health Lab 

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

Age Influenza-associated Death
0-18 2
19-49 13
50-64 31
65 + 87
All 133

 

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

Figure 7: Influenza Test Results Reported to the National Respiratory and Enteric Virus Surveillance System (NREVSS) Select Penn