Since they're all elderly I suspect they'll take it. Now if you're suggesting they will only appear to take it but not really because it's some kind of mind control substance and we'll all be under their control if we take it then you lost me. I'm seeing suggestions of such things elsewhere.
You're putting WAY too much thought into this.
The 3 people you mentioned could easily arrange to have the vaccine in the bottle replaced with saline.
The TV cameras, the viewing public and naive others wouldn't have a clue what was injected.
I'm sorry this is so complicated.