Seven months after a measles outbreak at a theme park infected more than 100 people, California may be well on its way to strengthening vaccination requirements for children — an policy that pediatricians say would boost immunization rates and stop the spread of disease. The bill, which was passed by the state legislature on Monday, strikes the personal belief exemption for vaccines and requires children who don’t meet immunization requirements to be homeschooled, unless they get vaccinated by kindergarten and seventh grade.