Biden, who will be sworn into office on Wednesday, outlined a $1.9 trillion stimulus package proposal last week, saying bold investment was needed to jump-start the economy and accelerate the distribution of vaccines to bring the virus under control.

"Neither the president-elect, nor I, propose this relief package without an appreciation for the country's debt burden. But right now, with interest rates at historic lows, the smartest thing we can do is act big," Yellen, a former Federal Reserve chair, said to the Senate Finance Committee.

"I believe the benefits will far outweigh the costs, especially if we care about helping people who have been struggling for a very long time," she said.