The co-chairs of President-elect Joe Biden’s COVID advisory board are emphasizing that “there’s no to time to waste” in the transition from President Trump’s administration to the incoming Biden administration when it comes to combating the coronavirus pandemic.

“We need to be allowed to immediately begin work with our colleagues in the current administration to plan to execute a national vaccination effort and end this pandemic,David Kessler, a co-chair of the advisory board and former FDA commissioner, told reporters on Tuesday.

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The president-elect's team cannot communicate with the Trump administration, Kessler said. And he stressed that it would be better for Americans on the whole for Biden's team can meet with government officials soon.

President-elect Joe Biden attends a national security briefing at The Queen theater, Tuesday, Nov. 17, 2020, in Wilmington, Del. (AP Photo/Andrew Harnik)

President-elect Joe Biden attends a national security briefing at The Queen theater, Tuesday, Nov. 17, 2020, in Wilmington, Del. (AP Photo/Andrew Harnik)

Fox News, other news networks and the Associated Press, projected that Biden would win the state of Nevada and the commonwealth of Pennsylvania, which would give the Democratic presidential nominee the electoral votes needed to defeat Trump and become president-elect. But Trump has yet to concede, as he hopes that a spate of apparent longshot lawsuits he’s filed and a couple of recounts in key states will reverse Biden’s victory.

The president on Sunday tweeted that "I concede NOTHING! We have a long way to go." And on Monday the president claimed on Twitter that “I won the Election!”

General Services Administration chief Emily Murphy, who was appointed by Trump, has yet to sign a letter of “ascertainment,” which until now was a mostly controversial-free process of declaring the winner of the White House race. The document gives the president-elect's transition team access to the federal agencies, and money to fund the transition.

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The Biden COVID-19 advisory board co-chairs spoke with reporters as the death toll from the pandemic reached nearly a quarter of a million people in the United States, with more than 11 million confirmed cases throughout the country since the coronavirus first swept into the nation in February and March.

Co-chair Vivek Murthy, a former surgeon general of the United States,  said many parts of President-elect Biden’s COVID-19 plan require working closely with the Trump administration.

And co-chair Marcella Nunez-Smith, Yale University associate dean for health equity research, said, “We need to work with the current administration immediately to coordinate on planning ... We need to be working together.”

She stressed that “we don’t have a second to spare. It’s not hyperbole.”

On Monday, the drug maker Moderna announced that its coronavirus vaccine was 94.5% effective, joining the pharmaceutical giant Pfizer as front-runners in the worldwide race to create a vaccine to stem the worst pandemic in a century.

Kessler, pointing to the enormous task of vaccinating the entire country, said that coordinating between Biden’s team and the Trump administration needed to start immediately.

“We don’t have a day to waste," he said. "Vaccine distribution is difficult and daunting under any circumstances."

The advisory board’s pleas came a day after the president-elect warned of dire consequences if the delay in kickstarting the transition and getting access to the federal agencies continues.

“More people may die if we don’t coordinate,” Biden said during a news conference in Wilmington, Del. He warned of a “very dark winter” due to the massive surge in new coronavirus cases this month.

Until the GSA greenlights the transition, the president-elect is prevented from receiving intelligence briefings from national security officials. The president-elect on Tuesday met with a panel of outside diplomatic, intelligence, and defense experts.

“I'm not being critical of ... Just stating the obvious. You know that I've been unable to get the briefings that ordinarily would have come by now,” Biden told the panel. “And so I just want to get your input on ... On what you see ahead. And, to state the obvious, there's no presidential responsibility more important than protecting the American people.”

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Vice President-elect Kamala Harris was on Capitol Hill on Tuesday. The senator from California, who sits on the Senate Intelligence Committee, received an intelligence briefing and took part in Senate votes.

I came up here today because I'm still a sitting senator and there was a very important vote that I wanted to weigh in, and I'm also a member of the Senate Intelligence Committee, and I take that part of my job very seriously as well," she said.

And in an apparent swipe at Trump’s refusal to concede, Harris said, “The American people want leaders that respect our democracy and our democratic process.”

Fox News’ Kelly Phares,Tara Prindiville and Madeleine Rivera contributed to this report