SACRAMENTO, Calif. — Last year's class of California kindergartners had a record 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 percentage is more than double that in certain parts of the state, particularly in more affluent coastal communities in Northern California.
The public debate on vaccination has been growing in California, where last year a spike in whooping-cough cases killed 10 babies and sickened more than 9,100 people. The outbreak prompted a state law that requires this year's middle and high school students to get whooping-cough booster shots.
Just last week, state health officials said the number of reported measles cases in California had reached a 10-year high of 28. Of those, 22 people were either unvaccinated or their vaccination status was unknown.
The percentage of parents who sign vaccine exemptions based on personal beliefs has been rising steadily since 2004. The increase coincides with rising use of the Internet for information, said John Talarico, chief of the immunization branch for the California Department of Public Health.
"We really think a lot of it is due to honest, valid concern that parents do the best thing for their child coupled with misinformation that gets out through various forms of communication," he said.
In some schools, as many as 30 percent of kindergartners are vulnerable to at least one vaccine-preventable communicable disease, according to data from the state Department of Public Health. The majority of schools have 100 percent immunization rates.
Certain areas of California have higher exemption rates than others. In Marin, Sonoma and Santa Cruz counties, more than 6 percent of incoming kindergartners in 2010 had parents file a personal belief exemption. By comparison, Los Angeles, San Francisco and Fresno counties had rates below 2 percent.
Parents can file two types of vaccine exemptions — medical or personal belief. The rarer medical exemption requires a doctor's signature and typically covers children who cannot be vaccinated because of auto-immune disorders or allergies; the personal belief exemption does not require parents to supply any information or explanation.
Doctors and medical experts say vaccines are a reliable means of preventing illness with little risk of injury, but some parents don't buy into the safety of immunizations. They cite concerns about vaccines making their children susceptible to autism or diabetes.
In a comprehensive safety review of vaccines issued last month, the Institute of Medicine found there is no link between vaccines and autism or diabetes. The institute, part of the National Academy of Sciences, found that serious side effects of vaccines are rare.
The increasing number of kindergartners entering school without immunizations poses a risk to others, especially children who have legitimate medical exemptions that prevent them from getting their shots, said Linda Davis-Alldritt, a school nurse consultant at the California Department of Education.