Bloomberg Economics economists Tom Orlik and Björn van Roye revised their forecast for global growth in 2020 to -4.7% from -4%.
They predicted a "disastrous" slide to come, and don't expect output to return to pre-virus highs until Q2 of 2021.
Investor hopes for a V-shaped bounce to 2019 highs were all but dashed by a discordant response to the coronavirus pandemic.
A swift recovery required quick-acting stimulus, virus containment in the second quarter, and synchronized lifting of lockdowns.