People kissing my child

I hate when people (family members) do this. I have told my younger sisters not to and they have stopped and respect my decision that until his older and has all his shots, not to kiss my child. But my dad wont stop doing it. And I have told him before countless times not to...but he always does it. Not even my baby's father kisses him (we dont live together). What else can I do? It really bothers me. I have never been close with my father and besides I feel like its not something you should do to a baby this young. My baby is 3 months old. Please advise. Thanks!