I don't think its actually practical to lie to Dad about boosters and he would almost certainly react very poorly if he discovered deception or to prevent someone from administering a jab.
Because Dr YouTube told him the vaccine was a serious risk to his health, but covid isn't.
And we could ask his cardiologist to speak with him about it, but as his last cardiologist was "trying to kill him" I think this would also go badly.
I am so upset. I can't actually shield him from the consequence of monotised lies.
And because he perceives vaccination as deadly, he would violently defend himself.