The FTC recommends maybe not taking a photo of your vaccination card and sharing it, because well, there could be quite a bit of information on that little card:
“Your vaccination card has information on it including your full name, date of birth, where you got your vaccine, and the dates you got it. When you post it to Facebook, Instagram, or to some other social media platform, you may be handing valuable information over to someone who could use it for identity theft.”
I don’t know, it seems like finding someone’s full name and birth date on social media isn’t really that hard, with or without the card, but maybe that information about where you got the shot and when could be used against you. It is private health information after all. Maybe it should stay that way?