Sweetie. one of my children did not have all of her vaccinations when I enrolled my children in public school a couple of years ago. I didn't want my children to have any more vaccinations than they already had, and I certainly didn't want my daughters getting the Gardicil vaccination that our Governor mandated a few years ago for all 13 year old girls.
I went to that link Uny added, found my state, and filled out the application for the vaccination waiver from our State Department of Health. It cost me $10 per child. The DoH mailed me a very lovely, official document that I copied and sent with all my children's enrollment paperwork. There has not been one peep. All these State agencies seem to need is the proper paperwork.
Go ahead and start the process now before the huge summer rush.