NEW YORK (Reuters) - As more Americans are vaccinated and households and businesses benefit from fiscal support, there are reasons to be optimistic about the U.S. economy, New York Federal Reserve Bank President John Williams said on Tuesday. Low interest rates reduce borrowing costs and help the economy rebound, Williams said during a virtual event organized by the New York Fed and AARP about small businesses. But fiscal support will also be important for the recovery going forward, Williams said.