The economy could take one to two years to rebound to full strength and the Federal Reserve and Congress, having already committed historic sums to fight the coronavirus pandemic, will have to commit trillions more, according to respondents to the CNBC Fed Survey.

With the Federal Reserve's balance sheet already at an unprecedented $6.45 trillion, the 36 respondents see it rising on average to $9.8 trillion. The additional trillions will be added by the end of the current quarter, the respondents expect. Congress, having already committed about $2.5 trillion, is seen putting in an additional $2 trillion.

"My guess is that the virus itself will largely disappear within a year, but that the structural social and economic impacts will be with us much longer," John Kattar, chief investment officer at Ardent Asset Management, wrote in response to the survey.

Jack Kleinhenz, chief economist for the National Retail Federation, said, "The policy response has been appropriate, but policy takes time to work its way into the economy and targeted sectors. … Many small businesses stand at risk."

Despite the massive relief, respondents still see the unemployment rate rising to 19%, hitting that level in August. It's expected to decline only gradually, to 11% by December and to 7% by the end of 2021. That would leave it at about double the rate before the crisis.