Washington Gov. Jay Inslee said the state has a "long ways to go" as it marks the one-year anniversary of the first U.S. case of COVID-19 being discovered in the state of Washington.

"We were hit the first and hardest," Inslee said during a press briefing Thursday. "Our recovery for the pandemic is progressing, and we have a long ways to go and we need to continue to learn from what we have experienced."

Since that first diagnosis, Washington state has reported 296,087 confirmed and probable COVID-19 cases as well as at least 4,065 deaths from the disease.

If the state "made different decisions," there could have been as many as 8,000 more people who died, Inslee said.

On the vaccination front, Washington state is administering on average more than 16,000 doses of COVID-19 vaccines per day, with plans to open four mass-vaccination sites next week, according to the governor.

Amazon will also open a one-day pop-up clinic in Seattle on Sunday, with the aim of administering 2,000 vaccines, Inslee said.

The governor urged residents to "remain diligent" amid the vaccine rollout.

"If we deviate from that course, we will have thousands more deceased Washingtonians in the months to come and that's just a hard fact," he said.

-ABC News' Michelle Mendez contributed to this report

New COVID-19 cases and deaths reported in the United States decreased substantially in week-to-week comparisons, according to a Health and Human Services memo obtained by ABC News Thursday.

Twenty-six states are in a downward trajectory of new cases, the memo stated.

The number of new cases confirmed from Jan. 15 to 21 decreased 20.4% compared to the previous seven-day period. The number of deaths decreased 9.2% during that time.

The national test-positivity rate dropped to 10.6% from 13.1% in week-to-week comparisons.

The percentage of hospitals with more than 80% of their intensive care unit beds filled and the percentage of inpatients with COVID-19 have also decreased slightly, according to HHS.

ABC News' Josh Margolin contributed to this report.

A Texas doctor is accused of stealing a COVID-19 vaccine vial that contained nine doses, according to Harris County District Attorney Kim Ogg.

Dr. Hasan Gokal of Harris County Public Health allegedly took the vial while working at a county vaccination site on Dec. 29. He was fired and has been charged with theft by a public servant, Ogg said.

"He abused his position to place his friends and family in line in front of people who had gone through the lawful process to be there," Ogg said in a statement. "What he did was illegal and he'll be held accountable under the law."

Gokal's lawyer, Paul Doyle, told Houston ABC station KTRK in a statement that the reason he took the vial was because the doses were going to expire.

"Dr. Gokal is a dedicated public servant who ensured that COVID-19 vaccine dosages that would have otherwise expired went into the arms of people who met the criteria for receiving it," Doyle said. "Harris County would have preferred Dr. Gokal let the vaccines go to waste and are attempting to disparage this man's reputation in the process to support this policy. We look forward to our day in court to right this wrong."

Dr. Anthony Fauci, chief medical adviser to U.S. President Joe Biden, said his “best-case scenario” is getting 85% of Americans vaccinated by the end of the summer.

"If we get 70% to 85% of the country vaccinated, let’s say by the middle of the summer, I believe by the time we get to the fall, we will be approaching a degree of normality," Fauci, who is also the director of the National Institute of Allergy and Infectious Diseases, told reporters at Thursday's White House press briefing.

"If we get 75% to 80% vaccinated, we could have a degree of herd immunity to get us back to normal," Fauci added. "The concern I have is people who have vaccine hesitancy who don't want to get vaccinated. We need to do a lot of good outreach."

Fauci said he believes Biden’s goal of 100 million vaccinations in his first 100 days as president "is quite a reasonable goal."

Despite rising COVID-19 infections in Japan, International Olympic Committee president Thomas Bach said Thursday that there is "no reason whatsoever" to believe the Olympic Games in Tokyo will not open on July 23 as planned.

"This is why there is no plan B and this is why we are fully committed to make these games safe and successful," Back told Japanese news agency Kyodo in an interview Thursday.

However, Bach admitted he could not guarantee that the stands would be full or rule out the possibility that the Games would be held without spectators, according to Kyodo.

The 2020 Summer Olympics were supposed to kick off in Tokyo last year on July 24. But in late March, amid mounting calls to delay or cancel the upcoming Games, the International Olympic Committee and Japan's prime minister announced that the event would be held a year later due to the coronavirus pandemic.

Now, Japan is facing a resurgence of COVID-19. The country of 126 million people reported the highest number of new cases in the Western Pacific region last week. The infection rate -- currently at 32.8 cases per 100,000 people -- increased by 4% over the previous week, according to the World Health Organization's latest COVID-19 weekly epidemiological update.

The Japanese Ministry of Health, Labor and Welfare confirmed 5,662 new cases of COVID-19 as well as an additional 87 fatalities from the disease on Thursday, bringing the cumulative totals to 348,646 cases and 4,829 deaths.

Japanase Prime Minister Yoshihide Suga has declared a state of emergency in Tokyo and 10 other prefectures due to climbing case counts and growing death tolls.