No, it's not a rock group. You're lucky if you can't remember. It's a disease that was gone, and now it's back. So, by the way, is whooping cough, another dreaded childhood disease that had been effectively wiped out.

Every child is supposed to be immunized before they start kindergarten. Children with medical issues, such as a weakened immune system, are entitled to medical exemptions. These children, along with family members who cannot be vaccinated, depend on the rest of the community to protect them. According to accepted public health standards, "herd immunity" requires that 92 percent of the students in the classroom be vaccinated. By vaccinating our own children, we protect them — and those children who cannot be vaccinated and might face the worst outcomes if they were to fall sick.

While all states require certain vaccinations, parents who claim that vaccinations are against their "personal beliefs" are entitled to exemptions. The number of parents seeking such exemptions has doubled in the past seven years, and, according to an analysis by the Los Angeles Times, the rates — and dangers — are actually greatest in private schools and many of the wealthiest public school districts.

In the Santa Monica-Malibu Unified School District, for example, the exemption rate is nearly 15 percent. In the Montecito district in Santa Barbara, more than 27 percent of the parents are claiming it is against their personal beliefs to vaccinate. Among private schools in California, nearly 25 percent of the kindergartens are reporting vaccination rates that put them below the 92 percent rate. In some cases, literally half of the students aren't getting vaccinated. Ten percent of the public school kindergartens surveyed reported that "herd immunity" no longer protects their students.

Parents who don't vaccinate their otherwise healthy children claim that they are protecting their children's health. I have yet to find a reputable doctor or public health expert who agrees. Measles and pertussis are potentially serious illnesses, even for healthy children. And they can be deadly for children and family members who cannot be vaccinated, already have compromised immune systems or are being treated for cancers — in short, for people who depend on the community to keep them safe.

Not vaccinating your child is both dangerous and selfish.

This is not a religious issue, at least not for the overwhelming majority of California residents who opt out of vaccination. The most dangerous schools in the state are schools populated by parents who think they know better than public health officials and, in making that mistake, are exposing not only their own children, but also their most vulnerable classmates and family members, as well as teachers and staff, to potentially deadly threats.

A few years ago, it was very "fashionable" to believe that vaccinations caused autism. I say "fashionable" because there was never one ounce of scientific proof establishing any such connection, and yet you could turn on your television and see the topic being debated as if it were one about which reasonable authorities could disagree. Reasonable authorities could not disagree. The so-called studies suggesting a link to autism were thoroughly and totally discredited. And yet the trend continues.

The number of measles cases in America reached a 20-year high last year. A preventable disease is back. California is facing a whooping cough epidemic this year.

Of course, parents should be able to raise their children as they please. I'm not one who thinks we need the state to tell us what our kids can eat for lunch or what size sodas they can buy. But vaccinations are another matter. Personal choice should not extend to exposing children to unacceptable and unnecessary risks — particularly when those being exposed are the most vulnerable among us, who have no choice.