California had also been struggling to maintain herd immunity vaccination rates- especially in higher income areas (just like us). After trying a variety of interventions- and following a measles outbreak associated with Disneyland- the California Assembly passed & Governor Brown signed Senate Bill 277 (in 2015) which abolished personal exemptions in California.
The intervention worked. In the following years, CA had sharp increases in vaccination rates among kindergarteners entering school. During the 2014–2015 school year the statewide kindergarten full-vaccination rate was only 90.4%. After implementing the new law, the kindergarten full-vaccination rate rose to >95% and has stayed there.
By the way- a few months ago the Second District Court of Appeal in Los Angeles found that the CA law didn’t violate freedom of religion or the right to an education.
The court said that… “Compulsory immunization has long been recognized as the gold standard for preventing the spread of contagious diseases”. The court said the new law was not discriminatory and was a valid measure to protect public health. Just saying.