Despite dips and disruptions from new variants of Covid-19, 2021 turned out to be a relatively positive year for economies and markets in most parts of the world. Growth rose above its potential after the severe recession of 2020, and financial markets recovered robustly. This was especially the case in the United States, where stock markets reached new highs, owing partly to the US Federal Reserve’s ultra-loose monetary policy (though central banks in other advanced economies pursued radically accommodative policies of their own).

But 2022 may be more difficult. The pandemic is not over. Omicron may n...