Earlier quoted context omitted.
How do you prove to people you are in a vaccine trial, do you have a card?
I have a "red alert" card so if I'm found unconscious a paramedic knows to contact the study team to find out if I'm in the control arm or I've had the active vaccine so they can rule out if it's important to why I was found unconscious! But it is just a piece of paper that the team printed out, and I think I lost it.
loses the single most important medical document that's going to save his life