Skip to main content
King County logo

Public Health interviews people who test positive for COVID-19 (cases) and investigates outbreaks.

This page shows the number of outbreaks that Public Health has identified across various settings and the number of cases associated with each type of setting. In addition, a table shows the number of outbreaks identified by month (listed by the month when Public Health was first notified of the outbreak).


Return to the COVID-19 data dashboards homepage


Outbreak definitions


Categories are mutually exclusive and a facility will be only included in one such category. Cases considered epidemiologically linked (epi-linked) to an outbreak share common characteristics, including but not limited to, close contact to a confirmed case, shared environment, or common exposure.

  • Childcares; including early learning programs, home childcare centers, and school-based childcare centers.
  • K-12 schools include both private and public schools.

For this category, an outbreak is defined by the following criteria:

  • 2 or more cases linked to the facility with epidemiologic link in a non-household setting.
  • Places of worship; including churches, temples, mosques, and other faith-based organizations.
  • Social gatherings including private events, weddings, parties and other large social gatherings.

For this category, an outbreak is defined by the following criteria:

  • 2 or more cases linked to the facility with epidemiologic link in a non-household setting

For this category, an outbreak is defined by the following criteria:

  • 2 or more cases linked to the facility with epidemiologic link in a non-household setting
  • Manufacturing including food processing, construction, agriculture, and other manufacturing sites
  • Food service establishments includes restaurants, fast food, taverns, and coffee shops.
  • Retail, hospitality or recreational worksites including grocery or other retail, hotels or other hospitality services, gyms, and recreational/outdoor worksites.
  • Shipping, delivery and utility worksites
  • All other non-healthcare worksites, including office-based worksites.

For this category, an outbreak is defined by the following criteria:

  • 2 or more cases linked to the facility with epidemiologic link in a non-household setting
  • Includes non-K-12 schools, such as vocational programs, college or university programs.
  • Dormitories or other college/university operated residences
  • University of Washington's sorority/fraternity chapter houses

For this category, an outbreak is defined by the following criteria:

  • 2 or more cases linked to the facility with epidemiologic link in a non-household setting
  • Includes adult family homes, skilled nursing and assisted living facilities

For this category, an outbreak is defined by the following criteria:

  • > 1 facility-acquired COVID-19 infection in a resident
  • > 2 COVID-19 infection in healthcare workers who were on site at any time during their exposure or infectious period
  • Includes home health agencies
  • Outpatient settings, including dialysis, primary care, dental and pharmacies

  • For this category, an outbreak is defined by the following criteria:
    • > 3 cases of COVID-19 infection cases in patients or HCW, with epi-linkage, AND no other more likely sources of exposure (who do not share a household, and are not listed as a close contact of each other outside of the workplace during standard case investigation or contact tracing) for at least 2 of the cases.
  • Including acute care hospitals and psychiatric hospitals

  • For this category, an outbreak is defined by the following criteria:
    • > 2 cases of COVID-19 infection in a patient 7 or more days after admission for a non-COVID condition, with epi-linkage
    • > 3 cases of COVID-19 infection in HCW with epi-linkage AND no other more likely sources of exposure (who do not share a household, and are not listed as a close contact of each other outside of the workplace during standard case investigation or contact tracing) for at least 2 of the cases.
      OR
    • A combination of > 3 cases of COVID-19 infection in HCW and patients with epi-linkage.

Limitations


The recent surge in cases has resulted in a heavy workload for Public Health staff, making it difficult to keep up with case investigations and increasing the likelihood that some outbreaks may be missed. Certain workplaces (such as healthcare facilities and larger work sites) may detect and report outbreaks to Public Health more reliably than others, so reported outbreaks do not reflect a complete picture of all outbreaks or associated cases.

Starting in August 2021, the outbreak investigation team shifted their priorities to focusing on LTCF, congregate settings, and school/childcare outbreaks. Decreases in outbreaks may be due to this change in prioritization.

In addition, in August 2021, the Case Investigation/Contact Tracing team has reduced questions regarding exposure settings, which may lead to a reduction in the number of potential outbreaks identified for investigation.

Table Summary

    # of outbreaks # of cases Avg. cases per outbreak
All outbreaks 2,312 17,960 8
Childcares, Extracurricular, and K-12 schools Childcare and extracurricular 202 1,114 6
K-12 schools 89 328 4
Community Outbreaks Places of worship 28 282 10
Social gatherings 48 415 9
Healthcare (non-LTC) Acute care and psychiatric 73 642 9
Home health agencies 26 134 5
Outpatient settings 31 157 5
Homelessness service sites Homelessness service sites
233 1,202 5
Long-term care or supported living Long-term care facilities 528 5,873 11
Supported living 61 689 11
Other congregate housing Other congregate housing 12 41 3
Other outbreaks Correctional Facilities 21 471 22
Senior living 23 101 4
University or colleges University or colleges 101 1,008 10
Worksites (non-healthcare) Food service establishments 171 710 4
Undetermined 12 85 7
Manufacturing 279 2,491 9
Other worksites (non-healthcare) 91 501 6
Retail, hospitality, and recreational worksites 229 1,410 6
Transportation, shipping, delivery and utility worksites 54 306 6

Table summary of outbreaks by month

Category Sub-category Not yet determined 2020 2021 Total
Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep
All outbreaks 10 2 87 96 38 65 131 122 109 183 292 234 169 111 132 174 90 43 72 132 22 2,312
Childcare, Extracurricular, and K-12 schools Childcare and extracurricular 1 4 3 2 4 4 4 6 10 34 17 8 5 18 21 12 4 13 29 3 202
K-12 schools 4 1 2 5 3 2 8 7 25 16 1 10 5 89
Community outbreaks Places of worship 2 1 5 6 1 1 1 6 1 2 2 28
Social gatherings
1 4 1 2 12 5 7 3 3 3 1 1 3 2 48
Healthcare (non-LTC) Acute care and psychiatric 1 4 4 3 4 6 6 5 7 10 8 1 3 1 1 1 7 2 73
Home health agencies 1 1 2 1 1 4 4 4 2 2 2 2 26
Outpatient settings
1 2 2 1 6 5 5 1 2 3 3 31
Homelessness service sites Homelessness service sites 6 34 3 1 9 6 8 7 21 29 19 9 9 13 9 6 3 35 6 233
Long-term care or supported living Long-term care facilities 2 2 56 42 21 23 31 30 15 31 62 76 51 13 3 18 10 5 9 23 5 528
Supported living
7 6 4 1 7 6 1 15 5 6 1 1 1 61
Other congregate housing Other congregate housing 1 1 3 1 2 1 1 1 1 12
Other outbreaks Correctional facilities 1 3 1 1 1 1 1 2 2 2 3 1 2 21
Senior living 6 1 2 1 1 4 3 2 2 1 23
University or colleges University or colleges 1 1 1 10 15 9 8 11 9 9 11 7 1 1 7 101
Non-healthcare worksites Food service establishments 1 13 16 7 12 26 25 12 6 3 13 14 9 5 8 1 171
Undetermined 1 1 1 1 1 2 1 1 1 2 12
Manufacturing 1 6 8 22 23 16 35 41 22 17 17 22 26 8 7 6 3 279
Other worksites (non-healthcare) 2 8 4 4 8 11 3 8 7 8 9 2 5 8 4 91
Retail, hospitality, and recreational worksites 3 15 16 13 16 31 24 16 16 28 23 9 5 12 1 1 229
Transportation, shipping, delivery, and utility worksites 2 5 6 5 6 7 2 3 3 1 5 2 2 4 1 54

Details about sector outbreaks


Disclosures are limited to acute care hospitals with 5 or more cases among staff and patients

  • Homeless service sites: Please refer to the weekly dashboard for more details

  • Long-term care facilities: Please refer to weekly dashboard for more details

  • Hospitals: Below are the hospital or acute care setting facilities with 5 or more cases among patients and staff.

Bolded outbreaks are currently ongoing (at least one case epidemiologically linked within the last 28 days).

Facility name First notified to PHSKC # of cases among patients # of cases among staff # of cases among patients and staff
Virginia Mason Medical Center
July 13, 2021 0 6 6
UW Harborview Mar 28, 2021 2 6 8
Virginia Mason Medical Center Feb 12, 2021 2 10 12
St. Francis Hospital Jan 26, 2021 23 23 46
Cascade Behavioral Health Hospital Jan 21, 2021 38 3 41
UW Medicine Valley Medical Center Jan 15, 2021 0 7 7
Fairfax Behavioral Health Hospital
Jan 15, 2021
5 5
UW Medicine - Montlake Jan 4, 2021 2 8 10
UW Medicine - Harborview Medical Center Jan 1, 2021 0 11 11
Fairfax Behavioral Health Hospital Dec 26, 2020 13 4 17
Virginia Mason Medical Center Dec 14, 2020 8 15 23
UW Medicine - Northwest Hospital Dec 3, 2020 18 14 32
UW Medicine Valley Medical Center Nov 30, 2020 4 15 19
Swedish Medical Center, First Hill Nov 13, 2020 0 20 20
Multicare Auburn Medical Center Nov 6, 2020 15 13 28
Cascade Behavioral Health Hospital Oct 6, 2020 15 14 29
UW North West Hospital Oct 4, 2020 1 3 4
UW Medicine - Harborview Medical Center  Oct 4, 2020
4 11 15
Swedish Medical Center, First Hill Sept 29, 2020 0 5 5
Virginia Mason Medical Center Aug 29, 2020 1 4 5
Swedish Medical Center, Cherry Hill Aug 13, 2020 1 7 8
Cascade Behavioral Health Hospital Aug 12, 2020 1 4 5