Trump announced via Twitter that Michael Flynn, his first national security adviser, has been granted a full pardon after being convicted following former special counsel Robert Mueller's investigation.

"It is my Great Honor to announce that General Michael T. Flynn has been granted a Full Pardon," the president wrote. "Congratulations to @GenFlynn and his wonderful family, I know you will now have a truly fantastic Thanksgiving!"

-ABC News' Elizabeth Thomas

On the eve of Thanksgiving, Biden delivered an address to the American people from Wilmington, Delaware.

The coronavirus pandemic was at the fore of Biden's message, which comes the same day that the U.S. passed the grim milestone of 260,000 lives lost to coronavirus.

Biden reflected on the first Thanksgiving authorized by the Continental Congress in 1777, saying that it took place "under extremely harsh conditions and deprivation." He added that a plaque still honors the spot where it took place, which reads: "This Thanksgiving, in spite of the suffering, showed the reverence and character that was forging the soul of a nation."

"Faith, courage, sacrifice, service to country, service to each other and gratitude even in the face of suffering have long been part of what Thanksgiving means in America," the president-elect said. "Looking back over our history, you see that it's been in the most difficult circumstances that the soul of our nation has been forged. And now, we find ourselves again facing a long, hard winter."

Biden urged Americans to remember "we're all in this together."

He said that like so many, his Thanksgiving celebration will look different this year, saying that his family will be breaking up into small groups to celebrate.

"I know how hard it is to forego family traditions," he said. "But it's so very important. Our country is in the middle of a dramatic spike in cases."

He noted that the nation is averaging 160,000 new cases a day and many local health systems are at risk of being overwhelmed.

"We owe that to our fellow citizens, who need access to hospital beds and care, to fight this disease," he said. "We owe it to one another. It's literally our patriotic duty as Americans."

Biden also urged Americans to keep hope, and referenced the positive vaccine development news.

"I'm hoping the news of the vaccine will serve as an incentive to every American, to take these simple steps to get control of the virus," he said. "There's real hope, tangible hope, so hang on."

Biden’s team has been officially briefed on the vaccine and federal response to COVID-19.

According to the HHS, leading the briefing was Deputy Surgeon General Rear Adm. Erica Schwartz, who has been acting as transition coordinator for the agency.

Also attending was Brian Harrison, who is chief of staff to Health Secretary Alex Azar, as well as project leads from Operation Warp Speed, the government's vaccine program.

“They are moving forward expeditiously, obviously our teams have had a lot of time to work through the core questions that they need to pose and the pieces of information that they most want to … have clear visibility into in terms of particularly vaccine distribution, testing and the PPE supply chain,” Biden Deputy Campaign Manager and Communications Director Kate Bedingfield said.

-ABC News’ Anne Flaherty and Molly Nagle

Pennsylvania Secretary of State Kathy Boockvar has asked the state Supreme Court to overturn a ruling Wednesday from a lower court imposing a preliminary injunction that paused the process of "perfecting" the certification of the Nov. 3 election.

The lawsuit was initially brought by Republican Congressman Rep. Mike Kelly, alleging that the state legislation that legalized the widespread use of mail-in ballots in the state was passed improperly. Kelly and his co-plaintiffs asked the court for an immediate stop to certification while the court reviewed the matter.

“This order does not impact yesterday’s appointment of electors,” Attorney General Josh Shapiro said in a statement to ABC News. Shapiro noted the plan for an immediate appeal.

In response to the lower court action, Boockvar's filing notes that Kelly filed the lawsuit over a year after the legislation was passed. The secretary's team also argued that Judge Patricia A. McCullough did not respond to objections the legal team filed and therefore entered her order before she should have. A hearing in the case was scheduled for Friday, but that could change depending on the response from the state Supreme Court.

-ABC News’ Matthew Mosk