Some doctors issuing these medical exemptions have been known to do so for flimsy reasons, leaving a rash of children vulnerable to serious medical issues. Northern California has 10 kindergartens with the highest rates of medical exemptions. Six of those kindergartens are in the Bay Area, with four of the six in Sonoma County.
At the California kindergarten with the highest medical exemption rate in the state, Sebastopol Independent Charter in Sonoma County, only 36 percent of students have all required vaccines; 42 percent are immunized against mumps, measles, and rubella. Fifty-eight percent of those students, the Times adds, have a medical exemption.
Doctors say just 3 percent of children at most should be exempt, due to serious health complications, such as a child undergoing chemotherapy.

Ninety-five percent of the population needs to be vaccinated to stave off an outbreak of a very contagious disease, such as one that broke out at Disneyland in 2014.
There is currently no authority in the state that decides on the validity of issued medical exemptions for vaccines.
Other California kindergartens with the highest medical exemption rates include:
58 percent: Sebastopol Independent Charter - Sonoma County
52 percent: Yuba River Charter - Nevada County
51 percent: Sunridge Charter - Sonoma County
43 percent: Live Oak Charter - Sonoma County
38 percent: Berkeley Rose School - Alameda County
38 percent: The New Village School - Marin County
37 percent: Coastal Grove Charter - Humboldt County
37 percent: The Waldorf School of Mendocino County - Mendocino County
35 percent: Summerfield Waldorf School & Farm - Sonoma County
33 percent: Santa Cruz Waldorf School - Santa Cruz County

The statistics reveal that Charter Schools are a vehicle for parents to avoid vaccinations required by public schools.
Alyssa Pereira is an SFGATE staff writer. Email her at or find her on Twitter at @alyspereira.