LONDON—Risks of a new COVID-19 hit to economic activity are clobbering expectations for rate hikes next year from the world’s major central banks, a potential setback for the dollar and other currencies where wagers had been most aggressive. Money markets no longer fully price a 25-basis-point interest rate rise by the Federal Reserve by June 2022, nor are they positioned for a full 10-bps hike from the European Central Bank by the end of 2022, as they were just a few days ago. And the chances of the Bank of England raising rates next month are seen around 53 percent, from 75 percent on Thursday. Those shifts come after the detection of a new coronavirus variant in South Africa triggered stricter border controls from several governments, as scientists sought to determine if the mutation was vaccine-resistant. “While central bank commentary has been focused on upside risks to inflation, this (new …