Kristen Bell: I Didn't Think I Would Be Pro-Vaccination Before I Had Kids

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star Kristen Bell admits to being "pretty crunchy" in her real life, but after giving birth to daughters Lincoln and Delta, the actress changed her mind about vaccinations.

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"I thought, oh well, I'm probably not going to vaccinate because we don’t need it, those diseases don’t exist," Bell told ET. "In the research I did, I found that there is actually a really big reason why we all need to. Which shocked me."

The actress and husband Dax Shepard insisted that friends and family be up-to-date on their shots before holding daughter Lincoln after her 2013 birth and they are doing the same with new baby Delta Bell. The House of Lies star has also been increasingly outspoken about her pro-vaccination beliefs in interviews and on social media in recent weeks.

"It's a very simple logic: I believe in trusting doctors, not know-it-alls," Bell told The Hollywood Reporter in a recent interview.

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While anti-vaccination advocates argue against getting immunized against diseases like polio and measles that haven’t threatened public health in America for several generations, Bell told ET that she now recognizes that the decision to vaccinate affects the general population.

"I think it's really important to acknowledge that we have something called the herd immunity, where there are people that cannot get immunizations because of autoimmune diseases or cancer treatments," she explained. "If we don’t get the vaccinations to keep them safe, then they're screwed."

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Bell stopped by ET back in October to talk about the Frozen phenomenon. See more in the video below.