Why So Many People Don't Get Flu Shots

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The U.S. is experiencing its worst flu season in decades. More than 180,000 people have been hospitalized with the flu this winter, and 7,400 have died, according to the U.S. Centers for Disease Control and Prevention. Yet a record low number of Americans are getting the flu vaccine, with 45 percent of children and 46 percent of adults vaccinated through January.

Public health officials typically try to encourage people to get vaccinated by sharing information like statistics on vaccine effectiveness, data on side effects, and risk calculations. But new research from Cornell University suggests that approach misses a crucial element about how people make health decisions.

Psychology professor Valerie Reyna and her team discovered that people's vaccination decisions aren't primarily driven by weighing facts and figures. Instead, they rely on what researchers call "gist"—the feeling or intuitive sense they have about vaccination.

"We make decisions based on the bottom-line gist of information: What does all this information boil down to? What's the decision really about?" said Reyna, the Lois and Melvin Tukman Professor of Human Development in the Department of Psychology at Cornell Human Ecology. "If we know the essence of how someone feels about these ideas, we can explain and predict their intentions with respect to vaccination."

Reyna's team tested this theory in a recent study of more than 900 people. Participants answered questions about their flu vaccination habits, their knowledge about the vaccine, and their perceptions of its risks and benefits.

The results were striking. Among younger adults, vaccine knowledge and accessibility explained 14 percent of the variation in who intended to get vaccinated. But when researchers included questions about participants' gist understanding—their overall impressions of risks and benefits—that number jumped to 58 percent. In the community sample, accounting for gist increased the likelihood of getting vaccinated from 57 to 80 percent.

The findings reveal that people who categorize vaccine benefits as "none" or "low" or risks as "medium" or "high" tend not to vaccinate, regardless of how much factual information they have. These simple, qualitative judgments proved far more powerful than detailed knowledge in predicting behavior.

"Part of our mind looks at details and precise facts, but the other part of our mind looks at the bottom-line, qualitative gist—and that's the more determinative part," Reyna explained. "People form a global impression of what they are told and experience, for example, 'Overall, I think the benefits from vaccination are high, and the risks are nil.' That would be a gist for people who get vaccinated, and that's what we showed."

Making Public Health Outreach More Effective

This research helps explain why traditional public health campaigns often fall short. Simply providing more statistics or listing facts doesn't necessarily change someone's gut-level impression about whether vaccination is worthwhile.

So, what should health communicators do differently? Reyna suggests focusing on sustained communication that helps people develop the right gist understanding. Rather than overwhelming people with data, practitioners should put facts into context and explain how vaccine risks and benefits connect to people's core values, such as protecting family members and neighbors, or making informed choices about one's own health.

"If you follow that recipe, you will be much more likely to make a difference with people, according to our research," Reyna said. "You have to take the right approach, and it's fundamentally different from what we're currently doing."

The take-home message: People make vaccination decisions based more on intuitive impressions than on factual analysis. To increase vaccination rates, health communicators should help people form the right "gist" by connecting vaccine information to their core values and providing contextualized communication rather than simply listing statistics.