The remarks marked Biden's toughest to date on Trump's failure to acknowledge his election loss and cooperate with the incoming administration for a peaceful transfer of power.

"More people may die if we don't coordinate," Biden told reporters during a news conference Monday in Wilmington, Delaware.

Biden and his aides - and a small but growing group of Republicans - have emphasised the importance of being briefed on White House efforts to control the pandemic and distribute prospective vaccines.

The Trump administration is working on its own distribution plan, while Biden's chief of staff indicated his transition team will proceed with their own planning separately because of the obstruction.

The outgoing president has refused so far to bend to pressure from Democrats or Republicans as he continues to dispute his loss to Biden, who has surpassed the 270 electoral vote threshold to become president and is leading Trump by more than 5.5 million votes nationally.

Cooperation between the outgoing and incoming administrations, traditionally a key component to the peaceful transfer of power in the United States, takes on heightened significance this year because of the coronavirus pandemic, which is escalating dramatically heading into the holiday season.

Biden called the vaccine distribution a "huge, huge undertaking," and said that if his team has to wait until he takes office to dig into the government's distribution plan, they will be "behind, over a month, month and a half".

Before taking questions, Biden outlined his plans to alleviate inequality and boost the US economy but said that any structural reforms depended first on reining in the pandemic and delivering more immediate relief.

"Once we shut down the virus and deliver economic relief to workers and businesses, then we can start to build back better than before," he said.

Biden has vowed to spend trillions of dollars to reinvigorate US manufacturing, expand health care coverage and combat climate change, among other priorities.

But his chief priority remains controlling the pandemic, which is surging to record levels and forcing state and local leaders to implement new rounds of restrictions on local businesses.

The president-elect has so far tried to sidestep difficult questions about whether he might support a short-term national lockdown to arrest the surge of coronavirus cases. Since defeating Trump, Biden has devoted most of his public remarks to encouraging Americans to wear masks and embrace social distancing measures.

But members of his coronavirus advisory board have been more specific. One member, Michael Osterholm, recently suggested a four- to six-week national lockdown with financial aid for Americans whose livelihoods would be affected.

He later walked back the remarks and was rebutted by two other members of the panel who said a widespread lockdown shouldn't be under consideration.

Australian Associated Press