In a signing message, Governor Brown wrote: "The science is clear that vaccines dramatically protect children against a number of infectious and dangerous diseases. While it's true that no medical intervention is without risk, the evidence shows that immunization powerfully benefits and protects the community."
Senate Bill 277 strikes California's personal belief exemption for immunizations,applies to public and private school students and children enrolling in day care. It's among the strictest vaccination guidelines in the country.
While medical exemptions would still be granted to children with serious health issues, other unvaccinated children would need to be homeschooled.
SB 277 was introduced after an outbreak of measles at Disneyland in December infected over 100 people in the U.S. and Mexico.
California joins Mississippi and West Virginia as the only states with such strict requirements.
The bill passed the State Senate on Monday.
For full coverage on the vaccine debate, click here.