A persons body should be utterly sovereign to themselves.
I don't know what country you live in, but where I come from children are to young to have their own autonomy in these kinds of situations. Furthermore, most governments do legislate what can and cannot go into our bodies, specifically drugs, and I do think it is appropriate to legislate on the use of vaccines. An important thing to remember is that vaccines do not only protect the vaccinated, but contribute to our herd immunity. If people don't get vaccinated, it could effect all of us.