How many families do you personally know who've lost children between the ages 3 and 10 to a disease of any sort?
My mother is in her eighties. When she was growing up EVERYBODY knew a family that had lost a child to a disease. Most knew more than one family who had. Imagine the day-care, or school you take your child to. Think how often these children get sick. Now imagine that 1 in 20, so probably 1 or 2 out of every class, was going to die from one of these diseases before 4th grade.
People today, don't fear what they really should fear. There are wolves circling, all the time, for your children. All the time. Just because you haven't seen them in decades, doesn't mean they aren't out there still, hungrily circling, waiting for you to let your guard down.
Anti-vaxxers are letting their guard down. Unfortunately, the children the wolves are going to get aren't necessarily their children. The wolves will exploit any opening, and they don't care which child they take.
That's the strongest analogy I have. We finally found a way to keep the wolves at bay, but it required everyone in the community to guard against them. It's a simple thing to do. It's been made as easy as possible to guard against them, but still, some get lazy, or forgetful, or refuse to believe in the wolves, and then the wolves slip through and take a child.