SACRAMENTO, Calif. (AP) -- Last year's California kindergartners had a record high percentage of parents who used a personal belief exemption to avoid immunization requirements, a development that concerns state health officials.

More than 11,000 kindergartners missed at least one vaccine in 2010 because their parents decided to forgo inoculation. At nearly 2.5 percent of the state's 470,000 kindergartners, that's California's highest rate of declined vaccines since at least 1978, the year before the measles, mumps and rubella vaccine was required.

The debate over childhood vaccinations has been growing throughout California, where last year a deadly spike in whooping cough cases killed 10 babies and sickened more than 9,100 people. The outbreak prompted a state law requiring middle and high school students to get booster shots before going back to school this year.