I remember a time when you had to show an international vaccine listing (yellow booklet) signed by your doctor to show you had all sorts of vaccines to enter Europe.
I still have one! The next generation of vaccine proof is going to be electronic......for good or for bad. I'm not tech savvy enough to understand how you get a global community all on the same page. There seems to be some uniformity or interoperability with pass ports between nations. The US Global Entry System is interoperable with the US passport system. Not sure how something like that could be used to electronically enter your vaccination information onto the chips on those cards. Visa Credit Cards work just about everywhere. I'm sure it can be done.
