I think there are a lot of children who grow up and one day feel very fortunate that they were not considered property of their parents and were removed from abusive homes and placed in ones where they were safer. I think there are also a lot of children who suffered abuse and even death at hands of abusive parents who, if they are or were alive today and grownup, are or would be very upset at the people who said nothing when they suffered all those years of abuse, the people who knew and stayed quiet, because they thought it was none of their business.
We talk about about the government as if it's their cold faraway inhumane thing. And sometimes people do experience that way. But, in a democracy, a government is in some ways just a group of village elders. There are 300-400 million of us here in the US, and we can't all go to the town hall and vote on every issue, nor would it make sense for all of us to be in law enforcement or to have an office in child protective services. So, we deputize people to do things for us collectively, to make sure that people have what they need and can feel safe and secure, especially with children. And though there is a special bond of love, responsibility, and often genetics between parent and child that allows us to back off at certain points and the parent raise the child as he or she feels fit, there are limits. There's a point at which we say "Look, this child is a person to, and we aren't going to let a parent break his ribs every night or sexually abuse him. This child is a person who has rights, and we have a responsibility to the child.". The child may be the ward of the parents, but the child is not the property of the parents. The child is to some degree his or her own person, and to some degree a member of society.
And, in a case like this, it becomes beyond just our responsibility to the one child, but the responsibility to children of parents who do the right thing, to *all* of the children, and their responsibility to us, and our responsibility to each other. Because there are some things like vaccinations where the cost is too steep to the children and to the society when too many parents refuse to do the right thing. And sometimes we have to, hopefully gently, step in and try to help the parents find it within themselves to do the right thing. And, in this case, the right thing is to let the family doctor vaccinate the child.