A California law that took effect last year is making it harder for parents to opt out of vaccinating their children — an issue that has taken new prominence as the state deals with an outbreak of measles.

State figures show personal-belief exemptions for kindergarteners dropped from 3.1 percent in 2013 to 2.5 percent last year.

A Los Angeles Times analysis published Friday (http://lat.ms/1Cm8LYJ ) found the rate also fell in school districts with high numbers of unvaccinated kindergarteners.

The law requires parents claiming a personal-belief exemption from vaccines to have a signed form from their doctor.

Public health officials have worried about the re-emergence of vaccine-preventable diseases like measles and whooping cough due to unimmunized schoolchildren.

A measles outbreak that originated at Disneyland last month has sickened six dozen people in six states and Mexico, with the majority of infections in California.

The vast majority of those who got sick had not gotten the measles-mumps-rubella, or MMR, vaccine.

While still a scourge in many corners of the world, measles has been all but eradicated in the U.S. since 2000 because of vaccinations. But the virus has made a comeback in recent years, in part because of people obtaining personal-belief exemptions from rules that say children must get their shots to enroll in school.

Others have delayed getting their children vaccinated because they still believe now-discredited research linking the measles vaccine to autism.