All this borrowing is required to plug the gaping hole the novel coronavirus has punched in the economy, as unemployment reaches levels not seen since the Great Depression. Few, if any, prominent economists or lawmakers opposed opening the government’s fiscal taps amid the current economic emergency. The Senate last month approved $2 trillion of crisis spending with a vote of 96 to 0.

Yet high debt loads already are straining many corporations, which may be forced to choose between skipping loan payments and laying off workers. Millions of consumers, too, face sizable monthly bills for student loans and credit cards, a burden that could weigh on any economic rebound.

The reliance on so much debt also will leave scars after the pandemic passes, economists say, making it difficult for policymakers to withdraw support and leaving the economy more vulnerable than before this crisis began.

“We should be very worried,” said Atif Mian, an economics professor at Princeton University who has written widely on the subject. “We are talking about a level of debt that would certainly be unprecedented in modern history or in history, period. We are definitely at a tipping point.”