Anti-vaccine sentiment is alive and growing in social media, with California, Connecticut, Massachusetts, New York and Pennsylvania showing the most negative tweets of any states, according to a new five-year CU Boulder study.

In Colorado, Fort Collins ranked particularly high for the prevalence of anti-vaccine tweets. Regions around the country with high affluence and/or a large number of new moms were most likely to be hotbeds of anti-vaccine Twitter users, the study found.

“The debate online is far from over. There is still a very vocal group of people out there who are opposed to vaccines,” said study co-author Chris Vargo, an assistant professor in the College of Media, Communication and Information. “Half of the talk online that we observed about vaccines was negative.”

For the study, published in the October issue of Social Science and Medicine, Vargo and co-author Theodore Tomeny, an autism researcher with University of Alabama, created a machine-learning algorithm to examine more than a half-million tweets from around the country between 2009 and 2015. To make the sample a manageable size, they looked only at tweets that referred to both autism spectrum disorder and vaccines.

Read more at CU Boulder

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