Perceptions of immunity shape vaccine decisions

New research investigates how people's perceptions of immunity can impact their vaccine decisions. Assistant Professor of Psychological Sciences at Rice University, Allie Sinclair, and her team from Duke University found that many individuals misjudge their level of immunity to COVID-19. Some believed they were more protected than their vaccination and infection records suggested, while others underestimated their protection.

These perceptions can influence whether they get vaccinated, take diagnostic tests, or adopt other health measures.

The study sought to understand why people weren't staying up to date with COVID-19 vaccinations. Sinclair and her colleagues discovered that a major reason was overconfidence in immunity. If someone felt overconfident in their protection, they might believe a vaccine wouldn't provide much benefit. To address this, the researchers developed an interactive "Immunity Estimator" tool that gives users personalized feedback on their likely protection against COVID-19 based on their vaccination and infection history, changes in the virus, and antibody decline rates.

The personalized approach proved more effective than existing impersonal methods at aligning participants' perceptions of risk with actual risk. It worked for both overestimate and underestimate groups, increasing perceived risk among those who hadn't realized their protection had waned and decreasing perceived risk among those who had overestimated it. The effect was particularly strong among older adults, who are more vulnerable to severe disease and could benefit most from maintaining protection.

Sinclair attributes the approach's success to two key learning processes: providing corrective feedback to engage brain systems that support learning and belief updating, and offering personalized information, as self-relevance plays a crucial role in guiding choices. The tool was found to be effective even two months after follow-up, with participants whose perceptions aligned with the estimates also showing higher vaccine uptake intentions.