As I understand it, you don't have to get patients (parents) to sign for any vaccine....it is implied consent when they sign in to be seen or have a physical done.
HOWEVER, we've learnt the hard way that parents will consent to a vaccine and then months later get irate because "I NEVER WANTED HER TO HAVE THAT VACCINE WITH MERCURY IN IT"!
So, we get all parents to initial their consent to the vaccine on out billing sheet (we still use paper billing forms). We save all the billing sheets, so if they say in the future "I didn't want her to have..." we show them their initials: end of argument!!