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The COVID Tracking Project will stop collecting data on March 7, 2021.

Washington Overview

Data Reporting Assessment (Learn more about data quality assessments)

Last updated

When Washington reports no data, several days of data, or unusual data (such as decreases in values that should increase), our volunteers note it here on the date the anomaly occurred. We also note here changes in our own methodology that affect the data.

Washington’s data is on a 1 day lag in our timeseries due to consistently updating after 7:30 pm Eastern Time, when we publish our daily update.

Washington State reports confirmed cases, laboratory tests, and deaths as of the previous day.

We report the most recent hospitalization data available for Washington. In some cases, this data may be reviewed and revised by the Washington State Department of Health. As a result, Washington considers hospitalization data complete after a 18-day lag period. In our data this lag is 20 days.

Currently and since November 21, 2020, Washington is reporting a variety of technical difficulties and an increased laboratory report volume. As a result, their data through these dates is incomplete and may include duplicate cases, missing negative test results, spikes due to backlog processing, and other abnormalities. Please exercise caution when looking at this data and be aware that 7 day averages are a more reliable metric than individual figures.

On February 15, 2021, Washington announced that there would be no update to their data due to the President’s day holiday. Because Washington’s data is on a one day lag in our timeseries, we were unable to update their data on February 16, 2021.

On February 10, 2021, Washington announced that their cumulative hospitalizations decreased by 14, noting that “in some cases, after a detailed information review, local health departments reclassify cases as not hospitalized or hospitalized for a reason other than COVID-19.” Because Washington’s data is on a one day lag in our timeseries, this affects our data for February 11, 2021.

On February 9, 2021, Washington announced that the higher number of deaths was due to a “data processing backlog” from February 8, 2021 being cleared. Because Washington’s data is on a one day lag in our timeseries, this affects our data for February 10, 2021.

On February 8, 2021, we began reporting Positive PCR tests (specimens), and Negative PCR tests (specimens) from Washington’s downloadable data.

On February 3, 2021, Washington reported that the “higher number of new deaths is due to a data processing backlog cleared today from February 2, 2021”. Because Washington’s data is on a one day lag in our timeseries, this will affect our data for February 4, 2021.

On February 2, 2021, Washington reported that its death data would not be updated until February 3, 2021. Since WA is on a one-day lag in our time series, the death counts reported on February 4, 2021 will include two days of data. In addition, possibly because of its ongoing “processing issues” beginning November 21, 2020, Washington’s cumulative death count decreased by two on February 3, 2021.

On January 20, 2021, Washington noted that there would be no update to their deaths due to “processing issues". On January 21, 2021, Washington's data processing backlog was cleared, causing a large increase in Deaths (confirmed and probable). Because their data is on a one day lag in our timeseries, this affects our data for January 21, 2021 and January 22, 2021.

On January 20, 2021, Washington noted that their would be no update to their deaths due to “processing issues”. Because their data is on a one day lag in our timeseries, this affects our data for January 21, 2021.

On January 20, 2021, Washington noted that the day’s hospitalization data is incomplete and should be interpreted with caution. Because Washington's data is on a one day lag in our timeseries, this will affect the data for January 21, 2021.

On January 17, 2021, Washington announced that there would be no update to their data on January 18, 2021 due to the Martin Luther King Holiday. Because Washington’s data is on a one day lag in our timeseries, we will be unable to update their data on January 19, 2021.

On January 16, 2021, Washington announced that they experienced “technical challenges processing COVID-19 data” and would not be able to update their dashboard. Because Washington’s data is on a one day lag in our timeseries, this affects our data for January 17, 2021.

On January 14, 2021, Washington announced that their hospitalization data was incomplete due to an interruption in their data reporting process. On January 15, 2021, they announced that their hospitalization data was “unusually high” due to a backlog from January 13, 2021 and January 14, 2021. Because their data is on a one day lag in our timeseries, this affects our data for January 15, 2021 and January 16, 2021. To avoid recording incomplete data, we did not update their Ever hospitalized on January 15, 2021 and urge caution when interpreting their hospital data from this time period.

On January 8, 2021, Washington noted that their hospitalization data for the day was incomplete due to a data processing issue, and their Ever hospitalized decreased by 11. Because Washington’s data is on a one day lag in our timeseries, this is reflected in our data for January 9, 2021.

On January 4, 2021, Washington's deaths decreased from 3,461 to 3,459 without explanation.

On January 2, 2021, Washington announced that there would be no update to their data dashboard due to “data processing challenges." Because Washington’s data is on a one day lag in our timeseries, this affects the data for January 3, 2021 and January 4, 2021; they have also provided an update on January 4, 2021, which is atypical of their reporting schedule.

As of December 20, 2020, Washington no longer updates their data on Sundays. Because Washington’s data is on a one day lag in our timeseries, we are unable to update their data on Mondays.

On December 29, 2020, Washington announced that their death data included a “backlog of roughly 200 cases that were previously unreported due to a processing issue”. Because Washington’s data is on a one day lag in our timeseries, this affects our data for December 30, 2020.

On December 25, 2020, Washington announced on their COVID-19 dashboard that there would be no update to their data on December 25, 2020 due to the Christmas holiday. On January 1, 2020, they noted that there would be no update to their data on January 1, 2021 due to the New Years holiday. Because Washington’s data is on a one day lag in our timeseries, we were unable to update their data on December 26, 2020 and January 2, 2021.

On December 23, 2020, Washington announced that due to an issue with their hospital reporting process, their hospital data was incomplete. Because Washington’s data is on a one day lag in our timeseries, this affects our data for December 24, 2020.

On December 18, 2020, Washington announced on their COVID-19 Data Dashboard that due to a change in the way they report COVID-19 deaths, a timing error caused an artificial decrease of 13 Deaths (confirmed + probable) and Deaths (confirmed) on December 18, 2020. Because Washington’s data is on a one day lag in our timeseries due to late updates, this will affect our data for December 19, 2020.

On December 19, 2020, Washington's total test number returned to its normal level, so we updated the December 18th value, replacing the anomalous 2,765,404 with the last value from December 17th (3,432,892), to avoid a huge one day drop in the cumulative test count.

On December 18, 2020, Washington revised down their total test numbers from 3,432,892 to 2,765,404. This might relate to the current note on the dashboard, stating: "Today’s total case counts may include up to 1,000 duplicates. Negative test results data from November 21, 2020 through today are incomplete, as are positive test results from December 16, 2020, thus testing and case numbers should be interpreted with caution. The Epidemiologic Curves tab is the most accurate representation of COVID activity and is updated daily as new cases are identified and duplicates are resolved."

On December 16, 2020, Washington added all Probable cases reported since June, 2020 to their data for December 16, 2020. Because Washington’s data is on a one day lag in our data, this affects our data for December 17, 2020. As of December 17, 2020, we are no longer able to report Washington’s Deaths (confirmed). On December 18, 2020, we backfilled the timeseries of Probable Cases, Confirmed Cases, and Cases (Confirmed and Probable) from data provided on Washington’s dashboard on December 17, 2020. “Since the data is by date of specimen collection, there is missing data for recent days.

On December 11, 2020, Washington Deaths decreased from 3016 to 2850. Washington noted that "As of December 10, 2020, death counts on our dashboard reflect those in our official vital records database (the Washington Health and Life Events System) where the cause of death was confirmed or suspected to have been COVID-19. If COVID-19 is later ruled out as the official cause of death, we will remove these deaths from our dashboard. We no longer report preliminary death information recorded in other systems."

On December 5, 2020, Washington announced that up to 90 of the deaths reported “yesterday” were incorrectly classified and were not due to COVID-19. Because we capture Washington’s data on a one day lag due to late update times, this will affect our data for December 5, 2020.

As of December 4, 2020, we are capturing Washington’s Currently hospitalized and Currently in ICU from the official Washington Department of Health COVID-19 - risk assessment dashboard. We have also applied this change retroactively going back to May 13, 2020 for Currently hospitalized, and September 19, 2020 for Currently in ICU.

On November 26, 2020, Washington announced on their COVID-19 Data Dashboard that there would be no update to their data on November 26, 2020. Because Washington’s data is on a one day lag in our time series due to late update times, we will be unable to update Washington’s data on November 27, 2020.

On November 24, 2020, Washington announced that the Department of Health will not be reporting new negative test results and temporarily removed the Total tests (in test encounters) metric from the dashboard. As a result all testing numbers were frozen until the state resumed updating them on December 4, 2020. Because Washington’s data is on a one day lag in our timeseries, this update will be shown on our data for December 5, 2020.

As of September 18, 2020, Washington's total test results are drawn from our totalTestEncountersViral field instead of calculated via positive+negative.

On August 26, 2020, Washington switched its total tests units to testing encounters, excluding future encounters from individuals who test positive. It also provided a full timeseries of the figure. This testing encounters figure is slightly different from how we define testing encounters in two ways: first, our definition of testing encounters includes encounters after a positive test, and second, it should be calculated not by summing resulted tests but by counting all daily tests in a separate reporting stream. Despite these differences, the historical and current values of Washington’s figure are still stored in our Total PCR tests (test encounters) field.

On August 2, 2020, Washington state Department of Health reported that "DOH is continuing to experience issues with its reporting system today. We are able to report cases, deaths and hospitalizations but have not reported new negative test results since 8/1."

On July 14, 2020, Washington state revised its count of COVID-19 deaths downward by 39, because it determined that even though those 39 people had tested positive for COVID-19, COVID-19 was not a contributing cause in their deaths.

On June 22, 2020, we updated previous values for cases and total tests in our time-series using data from Washington state's dashboard. This update caused an artificial decrease in cases and tests between June 21 and June 22.

On June 18, 2020, Washington revised its Total PCR tests (people) downward. On the same date, Washington decreased its count of COVID-19 deaths by 7, because it determined that even though those 7 people had tested positive for COVID-19, COVID-19 was not a contributing cause in their deaths.

On April 18, 2020, Washington state removed 190 confirmed cases that were discovered to be out-of-state residents tested in Washington laboratories.

Between March 31 and April 15, 2020, Washington state did not report Negative PCR tests (people).