The Congressional Budget Office projected on Monday that the pandemic would inflict a devastating long-term blow on the United States economy, costing $7.9 trillion over the next decade.

Without adjusting for inflation, the agency said, the pandemic would cost $16 trillion over the next 10 years. The estimates were an official tally of the damage from the crisis, reflecting expectations of dampened consumer spending and business investment in the years to come. Much of the diminished output was projected to be a result of weaker inflation, as prices for energy and transportation are expected to increase more slowly than they otherwise would have as Americans pull back on travel.

Phillip L. Swagel, the director of the budget office, cautioned that “an unusually high degree of uncertainty surrounds these economic projections,” because it remained unknown how the pandemic would unfold during the remainder of the year, or how social distancing and any future relief measures enacted by the federal government might affect its impact.

Around the world, developing countries, from Angola to Ecuador to Zambia, have also seen their finances shredded by the pandemic.