Outcome datasets

The data are provided weekly as Microsoft Excel files. There are separate files for each of the following geographic levels:

• King County
• 10 Region
• Census Tract
• City
• Health Reporting Area
• School District
• ZIP Code

Each Excel workbook includes data on the estimated 2020 population for each geographic level, counts of total COVID-19 positive cases, hospitalizations, and deaths. These data are presented in the following tabs:

• Overall counts of total COVID-19 positive cases, hospitalizations, and deaths
• Overall counts of total COVID-19 positive cases, hospitalizations, and deaths by age
• Overall counts of total COVID-19 positive cases, hospitalizations, and deaths by race/ethnicity
• Overall counts of total COVID-19 positive cases, hospitalizations, and deaths by sex
• WeeklyWeekly counts of total COVID-19 test results, positive cases, hospitalizations, and deaths. Test results are available through 4/28/2023.
• Daily counts of total COVID-19 test results, positive cases, hospitalizations, and deaths. Test results are available through 4/28/2023.

The Excel workbook for all of King County also includes these additional tabs:

• Weekly counts of total COVID-19 positive cases, hospitalizations, and deaths by age
• Weekly counts of total COVID-19 positive cases, hospitalizations, and deaths by race/ethnicity
• Weekly counts of total COVID-19 positive cases, hospitalizations, and deaths by sex

Vaccination coverage datasets

• Overall vaccination rates: This Excel workbook includes vaccination doses by day. Vaccination doses are described by general categories as CDC recommendations have evolved over time (i.e., original doses, 2022-2023 bivalent vaccine doses, 2023-2024 updated vaccine doses).

Outcomes by vaccination status datasets

There are four files of counts and rates of positive cases, hospitalizations, and deaths in King County by vaccination status. Vaccination status categories include:

• Not vaccinated
• Vaccinated, not up to date
• Vaccinated, up to date

The four files are described below:

• Counts by vaccination status: This Excel workbook contains counts and rates of outcomes by vaccination status, aggregated across major time periods (“phases”). The time periods are the Alpha phase (3-1-21 to 7-7-21), the Delta phase, (7-8-21 to 11-26-21), the first Omicron phase (11-27-21 to 3-27-22), the second Omicron phase (3-28-22 to 11-11-22), the third Omicron phase (11-12-22 - today), and the past 90 days,
• Daily counts by vaccination status: This Excel workbook contains daily counts and rates of outcomes by vaccination status.
• Counts by age group and vaccination status: This Excel workbook includes three tabs containing counts and rates of outcomes by vaccination status, aggregated across age groups and waves.
• Counts by race/ethnicity and vaccination status: This Excel workbook includes three tabs containing counts and rates of outcomes by vaccination status, aggregated across racial/ethnic groups and waves.

The following variables are used across many of the downloadable datasets and public dashboards.

• Geographic levels:
• 10 Region: Regions are groups of HRAs.
• Census Tract: Census tracts are defined by the United States Census Bureau.
• City: Includes incorporated cities and major unincorporated cities/towns in King County.
• Health Reporting Area (HRA): Neighborhoods that closely align with city boundaries and were created to aid in considering issues related to health status or health policies (learn more information about health reporting areas).
• School District: School districts are defined by state legislation.
• ZIP Code: ZIP codes are defined by the United States Postal Service.
• Population: Population is estimated for the specified geographic level. 2020 King County population estimates for incorporated cities, health reporting areas, ZIP codes, and census tracts are obtained from the Washington State Office of Financial Management (OFM). For unincorporated areas, population estimates were obtained from the 2018 American Community Survey because OFM does not provide population estimates for unincorporated areas.
• Note: Due to data quality issues with address information for negative test results, the number of tested individuals in zip codes 98164 and 98195 and census tract 53033008100 are greater than the total population in these areas.
• Test Results: Count of all COVID-19 PCR laboratory results reported to the Washington State Department of Health. If a person was tested multiple times, all their test results are counted until the date of the first positive test. If a person tests positive an additional time and it has been 90 days or more since their initial test, this test is counted as a new case. Test result data includes all PCR lab results that were received through 4/28/23.
• Positive Cases: Count of a positive COVID-19 antigen test or a confirmed positive PCR laboratory result reported to the Washington State Department of Health by a King County resident.
• Hospitalizations: Count of King Country residents who have tested positive for COVID-19 and have been hospitalized. In some cases, COVID-19 may be an incidental finding and not the primary reason for hospitalization. Hospital records are reviewed by Public Health – Seattle & King County investigators when there is a question about the primary reason for a hospitalization. Those that are deemed incidental are excluded from the official count of COVID-19 hospitalizations.
• Deaths: Count of King County residents who have died due to COVID-19. Prior to January 1, 2023, COVID deaths include decedents with a positive COVID-19 PCR or antigen test result, and had a cause of death that was confirmed or suspected to have been related to COVID-19. COVID deaths that occurred on or after January 1, 2023 require COVID-19 to be listed on the death certificate as either a contributing cause or other significant conditions, but no longer require a positive PCR or antigen test result.
• Up to date on COVID-19 vaccination: Count of King County residents who have received the recommended number of 2023-2024 updated vaccine doses, as entered in the Washington State Immunization Information System (WAIIS). The definition of up to date has changed over time as recommendations for COVID-19 vaccines have evolved. Percent of the population that is up to date uses the OFM population estimates described above as the denominator, which may lead to imprecise numbers for some groups with small populations and/or very high levels of vaccination coverage.
• Demographic characteristics: Demographic information is collected by interviewing cases, medical notes, test results, or by matching with other data sources. Large numbers of cases are missing demographic details, particularly race/ethnicity. Small numbers and missing data should be considered when interpreting the data, as some age groups and race/ethnicity groups have very small counts of outcomes.
• Age groups: Age is grouped into the following categories: 0-4, 5-11, 12-17, 18-34, 35-49, 50-64, 65-79, and 80+.
• Sex at birth: Sex at birth is categorized as female, male, and unknown.
• Race/ethnicity: Race/ethnicity categories are defined as follows:
• For individuals of Hispanic/Latinx ethnicity, race/ethnicity is categorized as "Hispanic"
• For individuals of non-Hispanic/Latinx ethnicity, race/ethnicity is categorized based on the race they selected
• For individuals of non-Hispanic/Latinx ethnicity who specified multiple race categories, race/ethnicity is categorized as "multi-racial"

Vaccination status is defined by CDC and determined based on the doses entered in the Washington State Immunization Information System (WAIIS). Vaccination status definitions have changed over time as recommendations have evolved. Learn more about staying up to date with COVID-19 vaccines. PHSKC data products use the CDC guidance released in October 2023, and the key vaccination status variables in the downloadable vaccination rates dataset and on our public dashboards are provided here:

• Completed original series: Count of King County residents who have received all doses of the original COVID-19 vaccine series. The original vaccine was designed to target the original virus that causes COVID-19. The original series, previously called the primary series, ranged from 1 to 3 doses depending on the vaccine manufacturer and person’s age. This count includes everyone who has completed at least the original vaccine series, regardless of whether they’ve received additional doses as boosters.
• Received at least one original booster: Count of King County residents who have completed the original series and received at least one booster dose of the original vaccine formulation. The original boosters were monovalent formulations which targeted the original virus that causes COVID-19. As of August 31, 2022, they are no longer recommended, in favor of updated formulations.
• Received 2022-2023 bivalent vaccine: Count of King County residents who have completed the original series and received at least one 2022-2023 bivalent vaccine dose. The doses are bivalent formulations which target the Omicron variant in addition to the original strain of the virus that causes COVID-19.  As of September 2023, the 2022-2023 bivalent vaccine is no longer recommended, in favor of the 2023-2024 updated COVID-19 vaccine.
• Received 2023-2024 updated vaccine: Count of King County residents who have received at least one dose of the 2023-2024 updated COVID-19 vaccine. These are doses of the updated 2023 formula (which targets the XBB lineage of the Omicron variant).
• Up to date: Count of King County residents who have received the recommended number of COVID-19 vaccine doses when eligible. Who meets this definition has changed as the vaccination recommendations have evolved.

A note on percentage estimates:

The vaccination coverage percentages, such as the percent of people who have completed primary series and the percent of people who are up to date, use the OFM population estimates described above as the denominator. This may lead to imprecise numbers for some groups with small populations and/or very high levels of vaccination coverage (capped at 95%).

Variable definitions

• Metric: The type of outcome included in the data
• Case: positive case of COVID-19. Counted on the date of an individual’s positive COVID-19 test.
• Hospitalization: hospitalization due to COVID-19. Counted on the date of an individual’s hospital admission.
• Death: death due to COVID-19. Counted on the date of death.
• Vaccination status: The vaccination status category used to compare outcomes and assessed on the date of the individual’s first positive COVID-19 test result for that disease event.
• Not vaccinated: individuals who have not yet received any vaccine doses of any COVID-19 vaccine.
• Vaccinated, not up to date: individuals who have received at least one dose of any COVID-19 vaccine, but who have not received all doses recommended for their age group.
• Up to date: individuals who have received all COVID-19 vaccine doses that are recommended for their age group.

Average positives/hospitalization/death Rate (in vax_daily): Rate of each outcome (count of each outcome divided by total population) averaged over the most recent 7-day period. Rates are age standardized.

• Adjusted positives/hospitalization/death Rate (in vax_demo_age, vax_demo_re, and vax_overall): Rate of each outcome (count of each outcome divided by total population). Rates are adjusted for age; for more information on adjustments, see the technical appendix.
• RR (in vax_overall): these variables are relative risks.

Data notes

Continuity correction in number of individuals not vaccinated

The number of not vaccinated individuals is calculated by subtracting the number of individuals with any COVID-19 vaccine dose from the estimated population. Data sources for population estimates are described in more detail in the section above. Among populations that are smaller in size, or very highly vaccinated, measurement errors in the number of not vaccinated individuals become apparent. These measurement errors are corrected using a 5% continuity correction. More information can be found in the technical appendix.

Up to date adapts over time

The definition of up to date is based on CDC recommendations and changes over time as new COVID-19 vaccine doses are recommended. This means that the definitions are accurate for each time frame. For example, individuals ages 18 and older who completed the original series were considered up to date until November 19, 2021 when CDC began recommending people in that age group receive an original booster dose. Therefore, starting on November 19, 2021, those individuals were considered vaccinated, not up to date because the requirements to be up to date had changed. Once individuals received an original booster dose, they were again considered up to date until recommendations evolved.

Age adjustment

Rates of COVID-19 metrics by vaccination status among race/ethnicity groups are calculated using statistical models that adjust for age. Age-adjustment is performed to account for differences in the age distributions of the underlying populations of each vaccination status category. These models allow for more accurate comparisons between the vaccination status categories, although they do not adjust for other factors that may affect outcomes, like predisposing conditions and behaviors related to COVID-19 prevention.

• Average adjusted positives/hospitalization/death Rate (in outcomes_daily): Rate of each outcome (count of each outcome divided by total population) averaged over the most recent 7-day period. Cases are counted on the date of an individual's positive COVID-19 test; hospitalizations are counted on the date an individual's hospital admission; death are counted on the date of death. Rates are age standardized.
• Adjusted positives/hospitalization/death Rate (in outcomes_age, outcomes_re, and outcomes_overall): Rate of each outcome (count of each outcome divided by total population). Cases are counted on the date of an individual's positive COVID-19 test; hospitalizations are counted on the date an individual's hospital admission; death are counted on the date of death. Rates are adjusted for age; for more information on adjustments, see the technical appendix.