The current outbreak, most cases of which can be traced to a Disney park in California, has sparked renewed debate over the wisdom of vaccinating kids. Health officials have urged vaccinations, but some parents avoid vaccinating their kids because of religious objections, or fears that they could lead to mental disorders such as autism.
The outbreak highlighted the fact that California, which has a 90.7 percent vaccination rate for preschool kids, nonetheless has pockets of people with relatively high rates of nonvaccinations.
"It is important that communities maintain high levels of MMR vaccination—because measles is so infectious—and especially when outbreaks are occurring around them," said Litjen Tan, chief strategy officer for the Immunization Action Coalition. "To have pockets where community immunity is below 90 percent is worrisome as they will be the ones most vulnerable to a case of measles exploding into an outbreak."
Health experts have pointed out that an often-cited study that had linked vaccinations to autism has been debunked as fraudulent.
And they've warned that low vaccination rates can lead to outbreaks of highly contagious diseases, with serious complications, including death.
"I understand that there are families that in some cases are concerned about the effect of vaccinations," President Barack Obama told NBC News earlier this week. "The science is, you know, pretty indisputable. We've looked at this again and again. There is every reason to get vaccinated, but there aren't reasons to not."
New Jersey Gov. Chris Christie and U.S. Sen. Rand Paul, R-Ky., both drew criticism when they spoke about vaccinations on Monday.
In an interview with CNBC's "Closing Bell," Paul called vaccines "a good thing" but said parents "should have some input" in deciding if their kids should get the vaccinations. He said it is "an issue of freedom."
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Paul, an opthamologist who is considering running for president next year, also said, "I have heard of many tragic cases of walking, talking normal children who wound up with profound mental disorders after vaccines."
That claim drew immediate fire from vaccination advocates for appearing to endorse the discredited link to autism.
Paul on Tuesday denied claiming that vaccines cause such disorders.
"I did not say vaccines caused disorders, just that they were temporally related—I did not allege causation. I support vaccines, I receive them myself and I had all of my children vaccinated. In fact, today I received the booster shot for the vaccines I got when I went to Guatemala last year," Paul said in the statement. He tweeted a photo of himself getting that shot.
Christie, during a visit to London, on Monday had said parents "need to have some measure of choice" in whether to vaccinate their kids.
After an outcry from vaccination advocates, Christie's office issued a statement saying, "With a disease like measles there is no question kids should be vaccinated." But he pointedly avoided questions from the media on Tuesday as his trip wrapped up.