The first confirmed case relating to the COVID-19 pandemic in the United States was announced by the state of Washington on January 21, 2020. Washington made the first announcement of a death from the disease in the United States on February 29 and later announced that two deaths there on February 26 were also due to COVID-19. Until mid-March, Washington had the highest absolute number of confirmed cases and the highest number per capita of any state in the country, until it was surpassed by New York state on April 10, 2020. Many of the deceased were residents of a nursing home in Kirkland, an Eastside suburb of Seattle in King County.

Governor Jay Inslee declared a state of emergency on February 29, 2020, which was followed by a statewide stay-at-home order on March 23 that would last at least two weeks.

Washington had 1,989,477 confirmed cases and a total of 16,100 confirmed deaths as of September 6, 2023. Public health experts agree that the true number of cases in the state is much greater than the number that have been confirmed by laboratory tests. It is very difficult to know the true number since most people experience only mild illness and testing is not widely available.

, Washington has administered 16.2 million COVID-19 vaccine doses, and has fully vaccinated 5.69 million people, equivalent to approximately 77% of the population. Approximately 15% of Washington residents have received the updated booster vaccine released in September 2022 and formulated for the SARS-CoV-2 Omicron variant.

On June 30, 2021, the state officially lifted capacity restrictions on businesses and most other activities, with the exception of large indoor events. Businesses were previously required to keep occupancy under 50% and maintain social distancing between patrons. Public transit systems were also permitted to operate at full capacity. The state of emergency declared by Governor Inslee expired on October 31, 2022, months after other restrictions had been lifted by state and local governments, particularly the City of Seattle.

Timeline

2020

January On January 21, the Centers for Disease Control and Prevention (CDC) confirmed the first U.S. case in a 35-year-old man living in Snohomish County. He had returned from Wuhan, China after visiting his family there, to the U.S., landing at Seattle–Tacoma International Airport on January 15, without any symptoms. He reported to an urgent care clinic with symptoms of pneumonia on January 19 and was transported to Everett's Providence Regional Medical Center the following day. He was released from the hospital on February 3 after two weeks of treatment, including the use of the anti-viral drug remdesivir, and went into isolation at home. Some earlier cases, not confirmed by PCR, have also been reported as far back as December 2019.

February

On February 19, 2020, a resident of a Life Care Centers of America nursing home in Kirkland, an Eastside King County suburb of Seattle, was transferred to a local hospital and later tested positive for COVID-19. On February 24, a 54-year-old man was transferred from the Life Care Center of Kirkland to Harborview Medical Center and died there on February 26. Also on the 26th, a woman in her 80s from the center died at her family home. Both were found to have had COVID-19 and in one case this was discovered in post-mortem testing. The two deaths were announced on March 3.

On February 28, a high school student at Henry M. Jackson High School in Mill Creek, Washington was confirmed as having the virus causing the school to be closed immediately; Mariner High School in Everett was also closed because a student's parent had the virus. The following day, researchers confirmed the coronavirus strain in the student's case may be related to the coronavirus strain in the first confirmed U.S. case from January 19, suggesting that the virus may have been spreading in the area for up to six weeks. Also on February 28, a woman in her 50s who had recently returned from South Korea and who was an employee of the United States Postal Service at its Network Distribution Center facility in Federal Way, King County, tested positive.

On February 29, Washington health officials made the first announcement of a death from COVID-19 in the United States (it was later discovered that a COVID-19 death occurred in California at least as early as February 6). A man in his late 50s with pre-existing chronic illness died at EvergreenHealth's hospital in Kirkland. He was not associated with the Life Care Center and although patients from the center were also in the hospital, it was not believed that any patients contracted the virus at the hospital. Officials said there was no evidence he contracted the virus through travel and they suspected community spread of the disease in King County. The man had not been tested for the virus until February 28, partly because the lab in Washington was not ready to conduct tests, and partly because until late February the CDC had been recommending testing only for those with COVID-19 symptoms who had recently traveled to China. Public health officials also reported two confirmed cases in the Life Care Center nursing home, including a woman in her 40s who was a health care worker at the facility.

March

March 1–5 On March 1, state public health officials confirmed two new cases in King County, both men in their 60s. One was hospitalized in critical condition at the Virginia Mason Medical Center in Seattle; the other was hospitalized in "critical but stable" condition at the Valley Medical Center in Renton. Those two cases were not linked to the cases in the nursing facility that were reported on February 29. Later the same day, officials reported four new cases associated with the Life Care long-term care facility: a woman in her 80s, a woman in her 90s, a man aged 70s who had died, and a man in his 70s in critical condition. Washington reported one additional case: a man in his 40s in critical condition, bringing the state's total to seven new cases reported on this day. The second death from coronavirus in the U.S. was reported at EvergreenHealth Kirkland. On March 2, officials announced another four deaths in the state, bringing the U.S. death toll to six. They also announced four new infections, bringing the state's caseload to 18, and the country's to 96. The total number of deaths in the state rose to nine on March 3. Additionally, Amazon.com confirmed that one of its Seattle employees had tested positive for coronavirus.

On March 4, officials reported the tenth death in the U.S. attributable to coronavirus. King County Public Health Department reported 10 new cases, including one death. All but one case were associated with the Life Care Centers facility. In the evening, Facebook announced that a contractor at its Stadium East office in Seattle was diagnosed with the virus; the office was shut down until March 9 and remote work was encouraged. On March 5, the Washington State Department of Health reported 31 new cases with the first new case reported outside of Snohomish and King counties. County case totals were Snohomish County 18, including 1 death; King County 51, including 9 deaths; Grant County 1 case. Later, public health officials reported an additional death on March 4, bringing the state total deaths to 11.

The United States Public Health Service (PHS) sent 28 uniformed officers to Kirkland around this time. The PHS team consisted of physicians, physicians' assistants, nurses, technicians and other medical care personnel.

March 6–10 On March 6, Microsoft announced that two of its employees in Seattle, including one working remotely for subsidiary LinkedIn, tested positive. Three new deaths were reported in King County; all died at the EvergreenHealth Medical Center. In addition, public health officials in Seattle announced that a part-time concessions employee at CenturyLink Field tested positive and may have exposed attendees of a February 22 Seattle Dragons game. The stadium, home to the Seattle Seahawks, Seattle Sounders FC, and Seattle Dragons, can seat up to 72,000 people. The University of Washington reported that a staff member in an office away from the main campus tested positive. Classes were to be held online starting March 9, until March 20. The suburban Northshore School District confirmed classes for its 23,000 students were suspended for up to two weeks. Starbucks closed one of its downtown Seattle locations after an employee tested positive. On March 6, Jefferson County reported its first confirmed case, a man in his 60s who had visited a family member in Kirkland. He was treated in a Seattle area hospital, then released to return home to recover. On March 7, the Department of Health confirmed 102 cases and 16 deaths. EvergreenHealth announced its 13th coronavirus death, bringing the total in Washington State to 17 deaths. Clark County announced its first positive test of the coronavirus in a man in his 70s.

On March 8, the Washington State Department of Health confirmed 136 cases and 18 deaths, mainly in King County. Later in the day, after the department of health report, an additional death was reported in Grant County. In the Seattle area, a staff member of the Aegis Living Marymoor assisted living facility in Redmond tested positive. The staff member has been isolated since February 28 after reporting symptoms. All Aegis Living communities are limiting non-essential visits. This is the fourth senior living facility in the Seattle area to report staff members who test positive. Kitsap County reported its first positive test, a Bainbridge Island resident in their 60s who was being kept in isolation. On March 9, the Washington State Department of Health reported 26 new cases and 3 new deaths as cases continued to appear in new counties. Life Care Center of Kirkland reported that 31 of its patients had tested positive. (City of) Snohomish schools would be closed beginning March 10 after a transportation employee was tested positive.

On March 9, a COVID-19 outbreak at a long-term care skilled nursing facility in King County, Washington led to 129 cases and 23 deaths. The infected were 81 out of approximately 130 residents, 34 staff members, and 14 visitors.

On March 10, the Washington State Department of Health reported an additional 105 cases, a 62% increase. Two additional deaths were reported in King County, in two separate nursing homes unconnected to the Life Care Center nursing home where most deaths have been reported. This brought the state total deaths to 24 with the majority, 22, in King County. Whatcom County declared a public health emergency after it reported its first case of the virus. The female patient self-isolated at home after receiving treatment at a local Bellingham medical center. Island County reported its first positive test. Skagit County reported its first positive test.

March 11–15 On March 11, five new deaths were reported, bringing the total to 29. Thurston County reported its first confirmed case.

Columbia County and Yakima County reported first cases on March 12. On March 13, Governor Inslee ordered all public and private schools closed for six weeks. On March 14, the Washington State Department of Health (DOH) confirmed three cases in Spokane County residents. On March 15, the American College of Emergency Physicians announced that an emergency physician at EvergreenHealth Medical Center in Kirkland was in critical condition with COVID-19. Lewis County announced their first case on March 15, with the patient being quarantined in a Cowlitz County hospital.

March 16–20