Have you ever declined any shots for your babe?

My babe got his 4 month shots. I’m not sure but part of me saying stop and think, does my baby really need it?! His Pedia trying enlightened me but every time he gets his shots we signed a waiver saying they are not reliable to any serious reactions which made me doubt. My sister in law did not give a single shot to any of her 4kids. They are vegan and looking healthy so far. Just made me think what are the other serious consequences of not taking it.