Dr Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases and the White House's top doctor responding to the coronavirus, said he jumped at the chance to continue working under the Joe Biden administration.
Mr Biden told CNN that he asked Dr Fauci to continue serving in his role, and also said he planned to make him the White House's chief medical adviser.
Dr Fauci told NBC News' TODAY that he eagerly accepted the position.
“Oh, absolutely,” Dr Fauci said. “I said 'yes' right on the spot, yeah.”
Ronald Klain, Mr Biden's incoming chief of staff, praised Dr Fauci.
"There are few public servants in our history who have served as long and as well and with as much distinction at Dr. Tony Fauci," he wrote in a tweet. "It will be a great honor to work with him again."
Mr Biden's first year as president will be dominated by the ongoing coronavirus and the roll out of the likely soon to be approved coronavirus vaccines from Pfizer and Moderna.
He said in his inaugural address he would be to ask Americans to wear masks for the first 100 days of his presidency.
"The first day I'm inaugurated I'm going to ask the public for 100 days to mask," Biden said. "Just 100, not forever — 100 days,” he said during a press appearance on Thursday. "I think we'll see a significant reduction that occurs with vaccinations and masking to drive down the numbers considerably.”
Dr Fauci said Wednesday he agreed with the move, but noted mask wearing would need to continue past the first 100 days.
“No, no. He didn’t mean it that way,” Dr Fauci said in an interview. “He just wants to get – it’s a good idea – uniform. He’s saying, hey, folks, trust me, everybody for 100 days. Now, it might be that after that, we’re still going to need it, but he just wants it — everybody for a commitment for 100 days.”
Mr Biden said Friday that he was confident he could broker a bipartisan stimulus deal in the US Congress for additional coronavirus relief.
A $908bn relief package is gaining momentum in the US Senate, and Mr Biden is likely referring to that package.
Sen. Bernie Sanders and Rep. Alexandria Ocasio-Cortez said they opposed the package, noting that it does not include another round of $1,200 stimulus money that would go directly to struggling Americans and lacks unemployment insurance.
"If people don't get UI assistance, and if they don't get a stimulus check, then relief isn't going to be felt in their lives, not in a substantive way," Ms Ocasio-Cortez told NBC News on Friday. "Will I support resources to hospitals and schools and firefighters? Absolutely. But I am extremely concerned that it's not going to solve the immediate problems that people have."
House Speaker Nancy Pelosi - who held out for a $2 trillion relief package before the election - is one of the proponents of the new package, despite it being significantly less than the Democrat's original relief proposal.
