[Caveat, let's not turn the comments into a giant debate between those for and against vaccines. Many other forums for that. Let's just try to give parents information they can use to make better choices of schools relative to whatever views they may have.]
Background: CA previously allowed opt-out of vaccination requirements for students attending schools, called Personal Belief Exemptions, or PBE. But a recent law makes it harder to opt-out. There are subtle details though.
First, current PBE rates for all schools in CA (public and private) can be found here (at the bottom of an article about recent overall trends in the rates):
Search for any string and all matching schools will be displayed in decreasing opt-out rate order. Just put in San Francisco for example to find the schools with the highest PBE rates in the city.
Second, two helpful links I found to help understand the recent law change and how it is being implemented:
My quick read is that existing exemptions are grandfathered: Anyone with an exemption on file by Jan 1, 2016 gets to avoid vaccination until they hit 7th grade (if they are in K already) and now that everyone knows the law is passed, they still have time to get new PBEs through the end of 2015. In addition, these grandfathered PBEs appear to be transferable school to school within California.
This means that PBE rates won't go down quickly at those elementary schools where they are already high---only slowly as new kids enter each year. And in fact, kids in kindergarten now will remain in the cohort that can have the highest PBE rates for the longest (since they won't hit 7th grade for many years).
It's worth also noting, since many people might not be aware, that many Waldorf schools (which typically have the highest PBE rates) consider "kindergarten" to be 2-years starting with 4-year-olds (the year that most other schools would consider the final year of preschool). Thus, this year's Waldorf 4-year-old K cohorts may have high PBE %s for 7 more years.
For families applying for kindergarten for next fall, it will be very hard to avoid vaccinating. Home schooling might be the easiest route to avoid it. (If homeschooling can be considered easy!)