We completed a trip in December 2021 to Munich, Milan, Zurich and San Francisco to visit family and friends for Christmas/New Years. In Germany and Italy our International certificate was accepted, but QR code could not be read.Recommend having a hard copy, as the digital copy was not always accepted and does not always show three vaccinations. In Munich you needed a RAT within 24hrs to visit museums. Be sure you have your passport, too. In both countries there were frequent, free RAT test stations. To enter Switzerland you need to fill out an on line declaration, to include where you will be staying and have a PCR with in 72 hrs. We took the train from Milan to Zurich, which I recommend, but there were no boarder checks. The next day the Canton contacted us send them a digital copy of our PCR result. At the tourist office at the main train station we converted our AU international certificate to the Swiss digital certificate ( 30 ChF). This certificate is good in the EU for one year. We are returning to Europe later in the year, so we are set.