Depends on which mythology you mean. If it is a Bram Stoker blood-sucker, nothing really, unless it is night and you happen to catch him hungry. Pretty much the same for the Anne Rice variety. If you mean a Stephanie Meyer vampire, it's really hard to say.
A vampire Cannot touch silver ! Because if a vampire touch a silver then it would be damage to his skin.
she is a vampire
if you touch a snake nothing happens
Touch screen.
Nothing happens.
they become lovers in vampire knight
because you touch yourself at night
they die.
.
She becomes a vampire
i don't even know wat that is
You'll have to watch Season 4 If you wanna find out.