Twitter is rife with antivaccine sentiment, with affluent new moms a prime source: study

The contention that vaccines cause autism has been refuted repeatedly, but a broad range of social media users still churn out messages backing the idea, a five-year study shows. And apparently, politics doesn't make a difference, but demographics does.

Antivaccine messages cropped up in red and blue states alike, the study found, with Twitter users in California, Connecticut, Massachusetts, New York and Pennsylvania posting the highest number of antivaccine tweets from 2009 to 2015, according to the study, published in the October issue of Social Science & Medicine. But the number of those tweets varied drastically within states from city to city.

The tweets supporting a vaccines-autism link didn’t seem to be randomly scattered, though. Researchers found that antivaccine tweets were more common in affluent areas or in cities with a large increase in the number of new mothers.

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For the study, three co-authors created a machine-learning algorithm to analyze more than half a million tweets that mentioned both autism and vaccines. Theodore Tomeny, an autism researcher with the University of Alabama; Chris Vargo, an assistant professor with the University of Colorado Boulder’s College of Media, Communication and Information; and NIH researcher Sherine El-Toukhy worked together on the research.

In the end, half of the social media posts sifted by the algorithm questioned vaccine safety.

"Unfortunately, the idea [of a link between autism and vaccines] is still very much out there, being promoted by a vocal minority online," Tomeny said in a statement. "That's problematic because often only one side of the story is being told."

In 2010, The Lancet retracted a 1998 study on only 12 children that had suggested the measles, mumps and rubella vaccine could lead to autism. Many studies have debunked the theory since and no others have substantiated it, and social media has become a battleground.

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The election of President Donald Trump helped step up the controversy by taking vaccine skepticism into the top echelon of U.S. government; the president himself has previously tweeted to question vaccine safety. But since winning the White House, he nominated CDC and FDA heads who are unequivocally pro-vaccines. Trump's FDA Commissioner, Scott Gottlieb, M.D., recently took to Twitter to take a firm stance against antivaccine sentiment.

Vargo stressed that he doesn’t see Twitter posts as representative of overall public opinion but rather a pulse of the level of antivaccine activity in an area. He suggested that the algorithm could be used to monitor the pulse of public opinion and map it out in real time so that public health agencies and healthcare professionals can develop targeted vaccine safety campaigns.