Well, I think that without question the genesis of this outbreak would be linked to an illegal. But, I imagine illegal children that are enrolled in public schools probably have a greater immunization compliance rate than the upscale private schools in California. Why? Because illegal kids get immunized for free, the parents don't want the hassle of justifying to the school why they aren't immunized, and they probably have better things to do than worry about what an idiotic celebrity says.
The private schools, OTOH, offer an entirely different dynamic. I wish the story would have indicated what percentage of those cases came from private school. I would wager it's large - or at least disproportionally large compared to public school kids.
My daughter is a physician in a larger city, a resident. She saw her first case of pertussis just this past summer. It was a 9-mos baby, who was the youngest of three kids, none of whom have been vaccinated for anything, by parental choice, not because economic condition. Your words were her words when describing the parents - criminal stupidity. FWIW, the child lived.
In our house in SC, my wife, daughter and 4 week old granddaughter all have whooping cough. No illegals nor public school for us. We also suspect that another friend of ours has it. Strange...