Should parents be allowed to choose whether to vaccinate their kids?

OAKLAND, Calif. -- The measles outbreak that started at Disneyland last month continues to spread, with at least 85 cases in seven states -- including an Arizona family of four, health officials announced Friday night.

The latest cases sparked a strongly-worded scolding from a public health official.

"This is a case where a family that has decided to not vaccinate their children are experiencing the consequences of that decision in a very real way" said Pinal County Public Health Director Tom Schryer. "These cases of measles will trigger a very intensive effort on the part of public health throughout the state and nation to identify others that they had contact with who are also unvaccinated so we can stop the transmission of this serious disease."

Most measles cases are in California, where parents are allowed to choose not to have their children vaccinated.

Six-month-old Livia Simon has been quarantined for three weeks at her home in Oakland. She was potentially exposed to measles at this nearby hospital by a child whose parents had refused a measles vaccine.

More than 30 other children are also in home isolation in the Bay Area, many under the age of one -- too young to be immunized.

"People say it's a personal choice not to vaccinate but it's a personal choice with a lot of possibly catastrophic consequences for other people," Livia's mom Jennifer Simon says.

California is one of 19 states that allow parents to refuse vaccinations based on their personal beliefs. A recent study shows many of these parents live in affluent neighborhoods.

Kaiser Permanente analyzed medical records of more than 150,000 children in Northern California. They found five clusters of under-immunization, mostly in the San Francisco Bay Area. About two out of 10 kids in the clusters either refused immunizations or were under-immunized.

"Some of the clusters were in places that we wouldn't necessarily have predicted," says De. Tracy Lieu, a researcher at Kaiser. "It tends to include a group of highly educated parents who have many questions about vaccines."

With one more week of quarantine, Jennifer Simon hopes her daughter will be okay.

"We've been really lucky she hasn't contracted measles," she says. "And so it's been an inconvenience but it hasn't been a tragedy -- and I don't want it to be a tragedy for anyone else."

Parents who refuse to vaccinate often fear rare side effects of vaccines.

California is trying to make it harder to get those personal belief waivers, now requiring parents to get a signature from a doctor saying they have been made aware of the risks of not vaccinating.