U.S. dollar bank notes are arranged for a photograph on September 7, 2017 in Hong Kong.

The dollar was steady on Tuesday and the yen stayed near three-weeks lows, as investors remained optimistic about progress toward a COVID-19 vaccine and the currency markets digested Monday's big moves.

U.S. drugmaker Pfizer Inc and German partner BioNTech SE said on Monday a large-scale clinical trial showed their vaccine was more than 90% effective in preventing COVID-19 - news which drove renewed appetite for risk that lifted global markets.