Lisa Marshall writes at CU Boulder:
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.
The authors note recent outbreaks of previously eradicated, vaccine-preventable diseases like measles and pertussis have been linked to refusal to vaccinate and anti-immunization-related beliefs. A few studies have provided clues as to what drives anti-vaccine sentiment, but they have relied on small samples of people.
Vargo wanted to use expansive data sets to ask the questions: How prevalent is the sentiment online; is it growing; and where does it cluster geographically?
Between 2010 and 2015, the study found anti-vaccine tweets became, overall, more common nationwide. As the number of households that made over $200,000 annually increased or the number of women who had delivered a baby in the past 12 months increased, so did the amount of anti-vaccine tweets.
Within states, sentiment varied widely from city to city.
For instance, in Denver, 24 percent of tweets over the course of five years were anti-vaccine while in Fort Collins, 59 percent were.
Vargo stressed he does not see Twitter posts as a representative sample of overall public opinion, but rather a pulse of the level of anti-vaccine activism in an area.
Ultimately, he envisions using the algorithm to create real-time maps similar to the one developed for the study that pediatricians could use to gauge anti-vaccine sentiment in their communities.