Tweets against vaccination contagious

Negative views spread more easily, study finds

On Twitter, negative views about vaccination not only spread more easily than positive ones, but people exposed to too many positive messages reacted against them. That’s according to Penn State University researchers who tracked about 350,000 tweets from more than100,000 people during the 2009 H1N1pandemic. Their study was published Thursday in the journal EPJ Data Science. The findings have implications that extend beyond the issue of vaccinations. “People are getting information about how to deal with their health from a variety of sources and increasingly from social media,” said the study’s lead author, Marcel Salathé, assistant professor of biology and computer science at Penn State. Twitter’s ongoing fluid conversation is a challenge for government agencies, such as public health, which move cautiously. “We’re slow on the uptake,” says epidemiologist Jordan Tustin, assistant professor at Ryerson University’s School of Occupational and Public Health. “We’re not even in the conversation most of the time. This is a big area of study right now, especially concerning behavioural research such as vaccinations.” Too often government agencies try to use Twitter in an authoritarian fashion, without much success, says Greg Elmer, director of the Centre for Social Media at Ryerson University. “Twitter is a bit of a frontier where people go to ask questions about rules,” he explains. “It’s playing an anti-authoritarian role in society.” The Penn State team found that exposure to negative feelings about the H1N1 vaccination spread, while positive sentiments did not catch on as easily.

They also found that people exposed to more antivaccination talk became more negative, but people getting more provaccination tweets did not as readily adopt a positive view.

But the most worrisome finding, said Salathé, is that intensive exposure to provaccination messages on Twitter increased the likelihood that the person expressed antivaccination views.

“This is not how we think it works,” said Salathé. “In public health you get the word out by banging the drum hard.”

From this study, Salathé can’t say if overexposure actually turned people off to vaccination. “They may have been negative from the get-go and all the positive messages made them cross a threshold and they talked back.”

The reaction to overexposure doesn’t surprise Elmer. “I call it the spam effect,” he said. “Twitter users want to maintain a certain anticommercial status. They don’t want unsolicited ads or institutional messages done in a public relations way.”

While more studies are needed to explore health messages on social media, the Penn State research has important implications, said Salathé. Public health officials can measure whether a communications strategy is working or not and change it quickly.

“They can detect patterns. If you overexpose a positive message, it may have the opposite effect,” said Salathé. “They have to be careful how they get the word out. More isn’t just better.”

Toronto Public Health uses Twitter for news releases and customer service. “People ask us questions on Twitter — where can they find a breastfeeding clinic or sexual health clinic — or maybe to complain about resources,” explained Nicole Ghanie-Opondo, a health communications team member who specializes in social media. Public health’s Twitter account, @TOPublicHealth, started just a few years ago and has 7,000 followers, she said. “We try to participate on Twitter, not dictate.”