Washington State
Influenza Update

Week 4
Jan 19 – Jan 25, 2020

Washington State Department of Health, Communicable Disease Epidemiology

Quick facts are below. See full report on pages 1-10 for details.
Flu activity in Washington is
currently

Take Me To:
•
•
•
•

Elevated

Number of reported labconfirmed deaths
2019-2020 season to date

Strains
Trends
Other viruses
Deaths

page 1
page 2
page 8
page 9

How do you stop the spread of flu?
Get vaccinated! After getting vaccinated,
also:

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5 child
47 adults
Most common type this week

A

More information:

Learn about flu and flu activity in Washington:
www.knockoutflu.org
National flu report from the CDC
Washington flu resources for providers
Read detailed Washington weekly flu report
following this page.

Find Washington flu and flu vaccine information at
www.KnockOutFlu.org.

DOH 420-100

To request this document in another format, call
1-800-525-0127. Deaf or hard of hearing customers,
please call 711 (Washington Relay) or email
civil.rights@doh.wa.gov.

 Washington State Influenza Update
Week 4: January 19 -January 25, 2020

Washington State Department of Health, Communicable Disease Epidemiology
Please note all data are preliminary and may change as data are updated.

State Summary: Flu activity is elevated
•
•
•
•
•

Fifty two lab-confirmed influenza deaths have been reported for the 2019-2020 season to date.
Twenty three influenza-like illness outbreaks in long term care facilities have been reported for the 2019-2020
season to date.
During week 4, 4.6 percent of visits among Influenza-like illness Network participants were for influenza-like
illness, above the baseline of 1.5 percent.
During week 4, 19.4 percent of specimens tested by WHO/NREVSS collaborating laboratories in Washington
were positive for influenza.
Influenza A and Influenza B were reported during week 4.

Influenza Laboratory Surveillance Data
Laboratory Data: World Health Organization (WHO) & National Respiratory and Enteric Virus
Surveillance System (NREVSS) Data Reported to CDC
CDC has generated separate graphs of data reported to CDC by public health laboratories (Figure 1) and
commercial laboratories (Figure 2). Table 1 combines the data from the public health and commercial
laboratories.
Table 1: WA Influenza Specimens Reported to CDC, Public Health Laboratories and Commercial
Laboratories
Week
01
02
03
04

A
(H1)
0
0
0
0

A (2009
H1N1)
16
24
13
11

A
(H3N2)
2
2
3
1

A (Unable
to Subtype)
0
0
0
0

A (Subtyping
not performed)
93
137
108
192

B
337
272
138
120

BYam
2
0
0
0

BVic
13
6
5
0

Total
Tested
2,483
2,382
1,502
1,670

% Flu
Positive
18.6
18.5
17.8
19.4

Figure 1: Influenza Positive Tests Reported to CDC, WA Public Health Laboratories

1

 Figure 2: Influenza Positive Tests Reported to CDC, WA Commercial Laboratories

 

 

 

 

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Outpatient Influenza-like Illness Surveillance
Influenza-like Illness Surveillance By Region
Figure 3 shows the percent of Emergency Department visits for a chief complaint of ILI or a discharge
diagnosis of Influenza for each geographic region in Washington state. Regions: West-Northwest: Clallam,
Grays Harbor, Jefferson, Kitsap, Lewis, Mason, Pacific, Thurston
Southwest: Clark, Cowlitz, Skamania, Wahkiakum Puget Sound: King, Pierce North: Island, San Juan, Skagit,
Snohomish, Whatcom Central: Benton, Chelan, Douglas, Franklin, Grant, Kittitas, Klickitat, Okanogan, Walla
Walla, Yakima East: Adams, Asotin, Columbia, Ferry, Garfield, Lincoln, Pend Oreille, Spokane, Stevens,
Whitman
Figure 3: Percent of Emergency Department Visits for ILI by Region, Washington

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 Outpatient Influenza-like Illness Surveillance Network (ILINet) Data
ILI is defined as fever (temp 100∘ F/37.8∘ C or higher) plus cough and/or sore throat. During week 4, 40 sentinel
providers in Washington reported data through the U.S. Outpatient Influenza-like Illness Surveillance Network
Surveillance Network (ILINet). Of 20823 visits reported, 957 (4.6%) were due to ILI, above the baseline of
1.5%.
In Figure 4, the baseline is for Region 10 (Alaska, Idaho, Oregon, and Washington). For the 2019-2020
season, the baseline is calculated differently than in previous seasons.
http://www.cdc.gov/flu/weekly/overview.htm
Figure 4: Percentage of ILI Visits Reported by Sentinel Providers, Washington, 2019

Table 2: Number of ILI Visits Reported by Sentinel Providers by Age Group, Washington
Week
01
02
03
04

Sentinel
Providers
46
43
41
40

Age 04
407
257
232
223

Age 524
391
309
248
295

Age 2549
424
313
234
278

Age 5064
113
111
81
98

Over
64
114
84
52
63

Total
ILI
1,449
1,074
847
957

Total
Patients
20,280
21,656
19,423
20,823

Percent
ILI
7.1
5.0
4.4
4.6

4

 Influenza Hospitalization Data
Reported Laboratory-Confirmed Influenza Hospitalizations (Spokane County Only)
Spokane Regional Health District requires hospitals to report laboratory-confirmed influenza-associated
hospitalizations. 143 lab-confirmed influenza hospitalizations have been reported since October 2018 (39
influenza A and 104 influenza B). See figure below, courtesy of Spokane Regional Health District.
Figure 5: Spokane Lab-Confirmed Influenza Hospitalizations by Month of Admission

Reported Laboratory-Confirmed Influenza Hospitalizations (Snohomish County Only)
Snohomish Health District requires hospitals in Snohomish County to report laboratory-confirmed influenzaassociated hospitalizations to the health district. See figure below, courtesy of Snohomish Health District.
Figure 6: Snohomish County Influenza Hospitalizations by Season 2013-CDC Week 4

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 Influenza-like Illness Syndromic Surveillance Data
ESSENCE Syndromic Surveillance Data
Figure 7 shows the proportion of visits at a subset of emergency departments across Washington for a chief
complaint of influenza-like illness, or discharge diagnosis of influenza, by CDC week. For this purpose, ILI is
defined as “influenza” or fever with cough or fever with sore throat.
For more information about Syndromic Surveillance in Washington State, see
www.doh.wa.gov/ForPublicHealthandHealthcareProviders/HealthcareProfessionsandFacilities/DataReportinga
ndRetrieval/ElectronicHealthRecordsMeaningfulUse/SyndromicSurveillance.
Figure 7: Syndromic Surveillance, Percentage of Hospital Visits for a Chief Complaint of ILI, or
Discharge Diagnosis of Influenza, by CDC Week, Washington, 2016-2019

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 Influenza-like Illness Outbreaks in Long Term Care Facilities
Long term care facilities are required to report all suspected and confirmed outbreaks to their local health
jurisdiction per Washington Administrative Code (WAC) 246-101-305. Long-term care facilities are required to
report the following:
•
A sudden increase in acute febrile respiratory illness over the normal background rate (e.g., 2 or more cases of
acute respiratory illness occurring within 72 hours of each other) OR
•
Any resident who tests positive for influenza
Recommendations for prevention and control of influenza outbreaks in long-term care facilities are available at:
http://www.doh.wa.gov/Portals/1/Documents/5100/fluoutbrk-LTCF.pdf

Local health jurisdictions in turn report long-term care facility influenza-like illness outbreaks to the Washington
State Department of Health.
Since Week 40 of 2019, 23 influenza-like illness outbreaks in long-term care facilities have been reported to
the Washington State Department of Health.

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 Seasonal Baselines and Epidemic Thresholds
Figures 9 and 10 are courtesy of Elaine Nsoesie of the University of Washington Institute for Health Metrics
and Evaluation and Al Ozonoff of Harvard Medical School. Methods are based on the work of Robert E Serfling
(1963). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1915276/
Figure 9 shows the percentage of specimens tested for influenza at WHO/NREVSS labs that are positive for
influenza by week. For week 4, the percentage of specimens positive for influenza is above the seasonal
baseline and below the epidemic threshold.
Figure 10 shows the percentage of visits that are for influenza like illness among ILINet providers. For week 4,
the percentage of visits for ILI is above both the seasonal baseline and the epidemic threshold.
The seasonal baseline is calculated using data from the previous five years, and the epidemic threshold is
1.645 standard deviations above the seasonal baseline. This method is similar to that used by CDC when
calculating pneumonia and influenza mortality, as described in http://www.cdc.gov/flu/weekly/overview.htm.
The intention of these models is to provide a data driven approach to determining when influenza has reached
an epidemic level. Under these models, influenza is considered to be epidemic when the percentage of
specimens positive for influenza is at or above the epidemic threshold, and the percentage of visits for ILI is
also at or above the epidemic threshold.
Taken together, these figures show that influenza activity is above both the seasonal baseline and the
epidemic threshold for week 4. Feedback on the use of these models is welcomed.
Figure 9: Percentage of Specimens Positive for Influenza, WHO/NREVSS labs

Figure 10: Percentage of Visits for ILI, Sentinel Providers

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 Other Causes of Respiratory Infections
During the 2019-2020 season, the following non-influenza respiratory viruses were reported to the National
Respiratory and Enteric Surveillance System (NREVSS).
For more information about NREVSS, see https://www.cdc.gov/surveillance/nrevss/index.html.
Figure 11: Respiratory and Enteric Viruses, Washington, 2019-2020 Season to Date

Table 3: Respiratory and Enteric Viruses, 2019-2020 Season to Date
Week

01
02
03
04

Reporters

17
17
11
10

Respiratory
Syncytial Virus

309
257
128
189

Human
Parainfluenza
Virus

17
13
14
7

Adenovirus

8
15
10
18

Coronavirus

26
31
18
16

Rotavirus

1
0
0
1

Enteric
Adenovirus

0
0
0
0

Human
Metapneumovirus

38
34
23
23

Rhinovirus

76
65
48
72

Enterovirus

0
0
0
0

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 Laboratory Confirmed Influenza-Associated Deaths
Reported Laboratory-Confirmed Influenza Associated Deaths
Note that these counts reflect only deaths officially reported to the Washington State Department of Health.
Note that each influenza season is reported as week 40 through week 39 of the following year.

Fifty two laboratory-confirmed influenza deaths have been reported since week 40 of 2019, 16 influenza A, 36
influenza B, and 0 type unknown. Most deaths have occurred in people with underlying health conditions, or in
people with no pre-existing conditions but who were elderly. Five deaths have occurred in children.
Table 4: Count and rate of reported laboratory-confirmed influenza-associated deaths by age group,
Washington, 2019-2020 season to date
Age Group (in years)
0-4
5-17
18-29
30-49
50-64
65+
Total

Count of Deaths
3
2
3
3
17
24
52

Death Rate (per 100,000 population)
0.66
0.17
0.25
0.15
1.19
2.05
0.70

Reported Laboratory-Confirmed Influenza-Associated Deaths, Past Seasons
For reference, lab-confirmed influenza death totals reported to the Department of Health for past seasons are
presented below in Table 5. Note that for the purposes of tables 4 and 5, each influenza season runs from
week 40 of one year to week 39 of the next (roughly October to October).
Past season summaries are available:
http://www.doh.wa.gov/DataandStatisticalReports/DiseasesandChronicConditions/CommunicableDiseaseSurv
eillanceData/InfluenzaSurveillanceData
Note that influenza deaths are likely under-reported. The reasons for this under-reporting vary. Influenza may
not be listed as a cause of death, influenza testing may not have occurred in a timely fashion to identify the
virus, or may not have been performed at all, and lab-confirmed influenza deaths may not have been
appropriately reported to public health.
CDC has published information about estimating seasonal influenza-associated deaths:
http://www.cdc.gov/flu/about/disease/us_flu-related_deaths.htm?mobile=nocontent
Table 5: Count of Reported Laboratory-Confirmed Influenza-Associated Deaths, Past Seasons to Week
4 and Total
Season
2019-2020, to date
2018-2019
2017-2018
2016-2017
2015-2016
2014-2015
2013-2014
2012-2013
2011-2012

Count of Deaths as of
Week 4 of Season
52
27
109
146
10
104
40
31
1

Count of Deaths Reported for the Entire Season (week 40
to week 39)
52
245
296
278
67
156
80
54
20

10

 Table 6: Count of Deaths Reported to WA DOH by County of Residence
Table 6 shows the count of laboratory-confirmed influenza deaths reported to the Washington State
Department of Health by county of residence. Deaths are from week 40 of 2019 through the present. Note that
due to reporting lag, counts may be different at the county level. Only deaths reported by the county as
“investigation complete” are included in the official Washington State Department of Health counts.
Note that due to reporting lag, counts may be different at the county level

County
Benton
Chelan
Franklin
Grant
King
Kitsap
Kittitas
Okanogan
Pend Oreille
Pierce
Snohomish
Spokane
Stevens
Thurston
Whatcom
Yakima

Count of Deaths Reported to WA DOH from week 40
of 2019 to present
3
1
1
3
11
4
1
1
1
9
5
4
1
2
3
2

Additional Resources
International Influenza Data: http://www.who.int/topics/influenza/en/
National Influenza Surveillance Report: http://www.cdc.gov/flu/weekly/
Washington DOH Influenza Information for Public Health and Healthcare Providers:
http://www.doh.wa.gov/ForPublicHealthandHealthcareProviders/PublicHealthSystemResourcesandServices/Im
munization/InfluenzaFluInformation#recommendation
Washington Local Health Department Influenza Surveillance Reports:
Clark County: https://www.clark.wa.gov/public-health/flu
King County: http://www.kingcounty.gov/healthservices/health/communicable/diseases/Influenza.aspx
Kitsap County: http://www.kitsappublichealth.org/Respiratory.pdf
Pierce County: https://www.tpchd.org/healthy-people/provider-resources/disease-information-forproviders/influenza/influenza-reports
Whatcom County: http://www.co.whatcom.wa.us/967/Influenza
Yakima County: http://www.yakimacounty.us/365/RSV-Flu-Stats

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