Just an idle thought..
Ask them what the side effects are of the 'vaccine' they are taking. If they say 'none' then simply ask them how many pharmaceutical products have ever had zero side-effects.
I think this might have a chance of disrupting the signal for common sense to kick in, maybe. Worth a shot?
I suspect many of the "vaccines" were simple placebos. But I have also read that an analysis of about 1,000 "vaccines" found that they are graphene oxide, nano particles and heavy metals (that came either from Dr. Ana Mihalcea or Karen Kingston). mRNA is too expensive to make billions of doses.