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More California parents sought medical exemptions from vaccinating school-age children

September 8, 2017

Research suggests some vaccine-hesitant parents in California successfully located doctors willing to grant medical exemptions to children without a contraindication to vaccination once that state eliminated its personal belief exemption.

The use of medical exemptions from the school vaccine mandate in California has tripled in the year since a law was enacted banning parents from using the personal belief exemption, according to the  paper by former Mason professor Paul Delemeter, Tim Leslie and Y. Tony Wang published in the Journal of the American Medical Association.

Issuing medical exemptions to children without a contraindication directly contradicts recommended practices, Yang said.

California Senate Bill 277 eliminated the personal belief exemption from school-entry vaccine mandates for the 2016-17 school year, leaving medical exemptions as the only option for kindergarteners to enter California’s public or private schools unvaccinated, according to the paper. In the year since the bill was enacted, medical exemptions increased to a level greater than 2.5 times that of the previous 20-year peak, Yang said.

Data shows California counties that had high incidents of personal belief exemptions prior to the law going into effect had the largest increases in medical exemptions after the law was implemented.

“Some California children may remain susceptible to vaccine-preventable disease outbreaks in the near future,” Yang said.

Overall, the new law had a positive impact during its first year, as more children were vaccinated, but the rise of medical exemptions warrants the attention of the medical and the public health communities.

Y. Tony Yang is an associate professor in the Department of Health Administration and Policy in George Mason’s College of Health and Human Services. He is an expert in health law, policy and ethics. He can be reached at or 703-993-9733.

For more information, contact Jamie Rogers at or 703-993-5118.

About George Mason

George Mason University is Virginia’s largest public research university. Located near Washington, D.C., Mason enrolls 35,000 students from 130 countries and all 50 states. Mason has grown rapidly over the past half-century and is recognized for its innovation and entrepreneurship, remarkable diversity and commitment to accessibility.