You must have Flash player installed. Click here to install.

MARK SAWYER, MD: Parents who choose not to vaccinate their children are not only making that decision for their children, but they're actually making that decision for other children as well. In order for our whole society to be protected we need almost everybody to be immunized; otherwise outbreaks of disease can occur.

MARY BETH KOSLAP-PETRACO, DNP(c), CPNP: When I hear parents say, 'Well, I'm not going to vaccinate and it's because it'll protect my child,' and my question to them is, 'Well, what about someone else's child who can't be vaccinated or who's too young to be vaccinated?' You're putting that child at risk.

Do you really want to do that to your neighbor? Is that what we really want to have for our society? What kind of a lesson is that teaching our children?

PAUL A. OFFIT, MD: Hundreds of thousands of people every year can't be vaccinated. They can't be vaccinated because they're getting steroids for their asthma or because they're getting chemotherapy for their cancer or because they're getting immunosuppressive therapy for their transplants.

They depend on the herd to protect them. They depend on living among a group of people who are highly vaccinated so they won't be exposed to those viruses or bacteria and it's frankly hard for them to watch herd immunity break down.

I got a call from a woman this morning who said to me, 'My child has leukemia. I now am going to be sending her into a classroom where half the classroom isn't vaccinated. That scares me to death,' and it should.

MARK SAWYER, MD: So for example in our recent outbreak of measles that we had in San Diego, some of the children who got the measles got it not because they weren't immunized because their parents chose not to have them immunized, they just were too young to be immunized. And they showed up in a doctor's office where the child with measles happened to be that same day and they were exposed to the measles.

PAUL A. OFFIT, MD: We had a measles epidemic in 2008 that was bigger than anything in more than a decade. We're seeing children now whose parents have chosen not to vaccinate them who now die from bacterial meningitis. That's a critical break in herd immunity.