SACRAMENTO — Gov. Jerry Brown signed one of the nation’s toughest mandatory childhood vaccination bills on Tuesday, moving to largely end exemptions from state immunization laws based on religious or other personal beliefs.It is not expected to have a big impact in Stockton Unified School District or other districts in San Joaquin County, where high rates of students are vaccinated.SUSD spokeswoman Dianne Barth said 97 percent of students in the district are [...]