“…and if they drink any deadly thing, it shall not hurt them; they shall lay hands on the sick, and they shall recover.”  Mark 16:18

He mentions two sets of people in the main verse:
⁃ the sick; upon whom hands are being laid
⁃ ‘they’ laying the hands
He didn’t mention what would happen if they laying hands were ever afflicted with infirmity, because all along he had been emphasizing the change that happens when a man believes in him.
He says there are visible signs that would differentiate those that have believed and those that have not.
Have you believed the gospel? Then you’ve moved from category A to category B; you are not the sick: that which could have been affected by infirmity have been subdued and overwhelmed by the life of God in you!
You were born of incorruptible (unspoilable) seed; and that is true about the organs in your bodies- they have become incorruptible, do you still whizz the way you did before you got born again? Relax! The asthma is gone, breathe in and out, thank God and eat well!
He also informs you that there’s something about your hands; before you got born again, you used your hands to take and give physical things- things external to you. Now, you can use those hands and give spiritual verities. Look at your hands; they’ve changed! They are now healing ministering channels- everything about you has changed!