The United States’ economy is expected to grow twice as fast as earlier forecasts predicted, according to a new report, which rests its optimistic outlook on the huge dose of fiscal stimulus and accelerating vaccine rollout. “The significant fiscal stimulus in the United States, along with faster vaccination, could boost U.S. GDP growth by over 3 percentage points this year, with welcome demand spillovers in key trading partners,” the Organization for Economic Cooperation and Development (OECD) wrote in its so-called interim March report, released on March 9 (pdf). The OECD’s closely watched December report, one of two main economic outlook products bridged by the March 9 interim projections, had predicted that the U.S. economy would grow by 3.2 percent; the interim report raises estimates for economic output this year to 6.5 percent. “Sizable risks remain,” the report cautions, however. Chiefly, slow progress in vaccine rollout and the emergence of new vaccine-resistant …