Thanks for reply. She was some variety of nurse, but they don't introduce themselves these days, nor wear a name/rank ID badge. And of course I don't know how long she'd been in the job, but she looked in her late 40s/early 50s.
I didn't say anything except that it was a Medicalert. As both my siblings wear one, I'd always been aware. Perhaps those of us who do wear them need to understand that others don't know about them, but it wasn't what I'd expected.