This AP story gives a lot of interesting detail on the current parental flight from childhood vaccination. In eight of the US states, over 5% of kids don't get the required vaccinations before kindergarten; their parents exercise the right to exempt them from some or all vaccinations, instead. The exemption rate is up in more than half of all states, but highest in Western and Upper Midwestern states.
Part of the trouble is that some states make it quite simple to exempt a child from vaccination--a note from home alleging a personal opposition to immunization does the trick in Colorado, for example. Some kids need to be exempt for medical reasons, of course, and some accommodation must be made for religious opposition to vaccination; but the response to mere personal or philosophical opposition to immunization should be education, at least in the first instance, rather than surrender. Parents who exempt their children are endangering them and other people as well.