I was also a bit shocked when I saw how high the Personal Belief Exemption was in some counties. Above 5% unvaccinated pretty much destroys herd immunity. So most of northern California is a no-go zone for people who appreciate the value of herd immunity.

What I have not seen, but would like to, is data for other states.

Fortunately, the highest-population counties in northern California are not too high - the number of schoolchildren in such counties is much lower that this map would indicate.

I’m in Australia so:

One in 10 Australian parents believe that vaccines can cause autism, and a another 30 per cent are unsure

http://mobile.abc.net.au/news/2017-03-08/children-without-va...