As of now, there are 88 confirmed cases of measles - most of them in California, with some in Arizona, Utah, Washington, Colorado, Oregon and even Mexico.
This outbreak, which originated at Disneyland last month, has stirred up a tremendous amount of debate over vaccines. Some parents are angrily wondering why other parents would choose not to vaccinate their child, when a bulk of evidence points to no connection between vaccines and autism.
But according to one study published in the journal Pediatrics, trying to spread a pro-vaccination message may actually push those opposed to vaccines even deeper into their beliefs.
Brendan Nyhan, one of the study's authors and assistant professor of government at Dartmouth who studies health policy, joins Take Two with more.
What made you and your colleagues study vaccine denial?
"My co-author and I had been studying political misperceptions for some time, and we came to realize that vaccines were a lot like politics, which I think any parent who's ever talked about them has realized. They're emotional and controversial, people feel very strongly about them, and it can often be really hard to change people's minds about them."
Tell us about how you conducted your study and what you found.
"We wanted to see what would happen if you tried to give people correct information, de-bunking the myth that vaccines cause autism, which is one of the most prominent myths about vaccines. We did a nationally represented survey experiment, with parents in the United States with children at home under the age of 18. And we tested what happened if they read information from the CDC presenting the scientific evidence that vaccines actually don't cause autism.
"And what we found was that information was effective in reducing belief in the myth itself that vaccines cause autism. But it had a potentially counter-productive effect on the parents who were most at-risk of opting out of vaccination. So for those parents who had the least favorable attitudes toward vaccines, giving them corrective information about the vaccine/autism myth actually made them less likely to say that they would vaccinate a future child, rather than more. And we think that suggests to think more carefully about how to present information to parents in a way that's going to be effective."
Why is that?
"What we think is going on is that when people are challenged in that way, they may think about why they hold those views in the first place. So if you're one of the parents who has concerns about vaccines, you may think about why you have those concerns in the first place, and in the process of bringing those to mind, defending those beliefs potentially, you make actually come to convince yourself more in those views than if you hadn't been challenged in the first place. This won't always happen, but it's a risk, and it's one we should take seriously."