Peter does indeed hold still, pointedly looking away from any needle action. Super powers or not, needles are the absolute worst okay. He's nervous okay he can't help it, sorry about his elevated heart rate. On the inside he's like AAAAAAAAAAAAAAAAAAAAAAHHH but on the outside he looks perfectly calm, at least.

Anyway, he gives her hand a little squeeze right back. See, he is perfectly fine. It's fiiiine. "If it can't help, don't worry too much. My body's a lot tougher than a normal person's, it should be able to fight this off on it's own."

He thinks. Maybe.