NEW YORK — The U.S. economy’s growth is likely slowing as 2020 comes to a close, but a growing number of economists expect it to claw back to its pre-pandemic strength by the second half of next year as vaccines for the coronavirus become widely distributed.

That’s the view from the latest survey of the National Association for Business Economics. It found that 73% of surveyed forecasters say the economy will return to its pre-pandemic level by late 2021. That reflects greater optimism than the forecasters had expressed a couple months ago, when just 38% of them said they thought a full recovery could occur before 2022.

Economists have been saying for months that only when vaccines are widely available to control or defeat the virus will the economy be able to sustain any meaningful recovery from the worst economic downturn since the Great Depression of the 1930s.

Hopes that one or more coronavirus vaccines will roll out soon are helping drive expectations higher, said the survey’s chair, Holly Wade.

“NABE panelists have become more optimistic, on balance,” Wade said, “with nearly one-third revising their outlook higher based on recent news of effective vaccines.”

Pharmaceutical companies are asking U.S. regulators to allow the use of their vaccine candidates after reporting encouraging data from clinical trials. The hope is that a wide rollout would mean fewer restrictions on businesses next year and more confidence among shoppers and companies to spend more.