The US CDC card is very bare bones. Just the dates the jabs were administered along with the vaccine name and batch number, also the name of the nurse who gave the jab.... All handwritten. We had the hospital print out secondary verification (basically just the same information on hospital letterhead along with a supervising physician's signature/stamp) in anticipation of the likely wave of people coming up with fake vaccination cards.... that coupled with photos of us at the hospital getting the jabs, ready to whip out should our jabs be questioned by airlines or immigration anywhere. I would have done the old school newspaper prop to timestamp the photos but couldn't find any shops still selling newspapers. ????
Hopefully there will be some kind of international standard that some techie will come up with, maybe blockchain based.