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Affective Risk Appraisal and Vaccine Hesitancy: A Structural Equation Model of Fear, Perceived Risk, and Vaccination Experience

Based on a structural equation model of 2,204 adults, this study finds that health-related fear significantly increases vaccine hesitancy primarily through the mediation of perceived vaccine risk, a pathway that is notably stronger among individuals lacking prior vaccination experience.

Original authors: Mingze Han

Published 2026-08-19

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CC BY 4.0

Original authors: Mingze Han

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

In the modern world, making health decisions often feels like navigating a storm of information. We are told that vaccines are safe and effective, yet many people still hesitate to get them. This hesitation is not always about a lack of facts; often, it is about how those facts feel. Scientists who study these decisions have long known that emotions play a huge role. When people feel afraid, their brains tend to judge a situation as more dangerous, even if the statistical odds of harm are low. This is a natural human reaction: fear acts like a signal that says "be careful," but sometimes that signal is too loud, drowning out the quieter, more accurate data about safety. To understand why people delay or refuse vaccines, researchers must look beyond simple knowledge and examine how fear shapes the way people perceive risk.

A researcher at the University of Oxford set out to map this connection between fear and vaccine hesitation. They wanted to know if the fear people feel about vaccines directly causes them to hesitate, or if that fear first changes how they judge the risk of the vaccine itself. To find the answer, they surveyed more than 2,200 adults in early 2024. The participants were chosen to represent a broad mix of ages, backgrounds, and locations. The researcher asked them detailed questions about how afraid they felt regarding vaccines, how risky they believed the vaccines to be, and how much they hesitated to get them. They also asked whether the participants had received vaccines before, as this experience might change how they process fear.

The study found that fear is indeed a powerful driver of hesitation, but it works through a specific mental process. When people feel high levels of health-related fear, they are much more likely to perceive the vaccine as dangerous. This feeling of danger, in turn, makes them more likely to delay or refuse the shot. The researcher calculated that this feeling of risk explains nearly half of the link between fear and hesitation. In other words, fear does not just make people hesitate on its own; it first convinces them that the vaccine is a greater threat than it might actually be. Even after accounting for this change in risk perception, a direct link remained, suggesting that fear can also cause hesitation through other paths, such as a general desire to avoid the situation or a lack of trust in medical authorities.

The study also revealed that this process is not the same for everyone. The connection between fear, perceived risk, and hesitation was strongest among people who had never been vaccinated before. For those who had already received vaccines, the link was weaker. This suggests that having a direct, personal experience with a vaccine can act as a buffer. When a person has already gone through the process without severe problems, they have real evidence to counter their fears. They do not have to rely as heavily on imagined risks or stories they have heard from others. For those without this experience, fear remains a dominant force, shaping their view of the vaccine as a significant danger.

These findings offer a clear direction for how health officials and communicators should talk about vaccines. Simply providing more facts or statistics is often not enough to calm deep-seated fears. If a person feels afraid, they may understand the numbers but still feel the vaccine is unsafe. Effective communication needs to address both the facts and the feelings. It should acknowledge the fear, explain how safety is monitored, and help people understand that their perception of risk might be influenced by emotion rather than reality. For those who have never been vaccinated, the message needs to be even more supportive, offering reassurance about the procedure and the safety of the shot to help build the confidence that comes from experience. By understanding that fear changes how people see risk, public health efforts can better support people in making informed choices.

Technical Summary: Affective Risk Appraisal and Vaccine Hesitancy

Problem Statement
Vaccine hesitancy remains a critical barrier to immunisation programmes, particularly within digital health communication environments where emotionally salient narratives spread rapidly. While existing literature identifies correlates such as trust, misinformation exposure, and the "5C" psychological antecedents (confidence, complacency, constraints, calculation, collective responsibility), there is a theoretical gap in understanding how affective states translate into subjective risk judgments. Current research often treats emotions (fear) and cognitive judgments (risk perception) as parallel predictors rather than components of a unified appraisal structure. Furthermore, few studies utilize validated latent constructs and structural modelling to examine how digital communication environments interact with individual-level affective-cognitive processes to shape vaccine attitudes. This study addresses the need to model the specific pathway through which health-related fear influences vaccine hesitancy via perceived vaccine risk, and whether this mechanism varies by prior vaccination experience.

Methodology
The study employed a cross-sectional survey design with a demographically quota-balanced online sample of 2,204 adults (aged 18–75) recruited between February and June 2024. Data collection utilized Qualtrics XM via Prolific Academic.

Measures: Three primary latent constructs were measured using multi-item Likert-type scales (1–5):
1. Health-related fear: A five-item scale developed for this study based on Protection Motivation Theory (PMT), assessing fear of side effects, anxiety, long-term safety concerns, and discomfort with rapid development.
2. Perceived vaccine risk: A five-item scale adapted from general risk perception theory, capturing subjective judgments of danger, probability of harm, risk-benefit imbalance, and uncertainty.
3. Vaccine hesitancy: A five-item composite scale adapted from the WHO SAGE definition and the 5C framework, measuring delay, doubt, postponement, and avoidance preferences.
- Controls: Seven variables were included: age, gender, education, income, prior COVID-19 vaccination experience (categorized as none, one dose, or two+ doses), chronic health conditions, and recent exposure to anti-vaccine content.
Analytical Strategy: Analysis was conducted using R (lavaan package). The approach involved:
1. Confirmatory Factor Analysis (CFA): To validate the three-factor measurement model, assessing factor loadings, reliability (Cronbach's $\alpha$ , McDonald's $\omega$ ), convergent validity (AVE), and discriminant validity.
2. Structural Equation Modelling (SEM): To estimate direct and indirect associations among fear, perceived risk, and hesitancy.
3. Mediation Testing: Bias-corrected bootstrapping with 5,000 resamples was used to estimate indirect effects and confidence intervals.
4. Robustness Checks: Included alternative estimators (WLS, OLS, ordinal logistic), common method bias diagnostics (Harman's single-factor test, marker-variable approach), and subgroup analyses based on prior vaccination experience.

Key Results
The measurement model demonstrated satisfactory fit ( $\chi^2(87) = 124.3$ , CFI = .963, TLI = .954, RMSEA = .058, SRMR = .054) and strong internal consistency ( $\alpha$ range: .876–.891). The structural model supported the hypothesised affective-cognitive pathway:

Direct Associations: Health-related fear was positively associated with vaccine hesitancy ( $\beta = .214$ ) and perceived vaccine risk ( $\beta = .463$ ). Perceived vaccine risk was positively associated with hesitancy ( $\beta = .371$ ).
Mediation: The indirect association from fear to hesitancy through perceived vaccine risk was statistically significant ( $\beta = .174$ , 95% CI [.148, .200]). This indirect pathway accounted for approximately 45% of the total fear–hesitancy association.
Model Explanatory Power: The model explained 41.2% of the variance in vaccine hesitancy.
Subgroup Heterogeneity: The indirect pathway was stronger among participants without prior vaccination experience ( $\beta = .198$ ) compared to those with two or more prior doses ( $\beta = .149$ ). This suggests that individuals without prior vaccination experience rely more heavily on fear-linked risk appraisal.
Control Variables: Higher education, income, age, and prior vaccination experience were associated with lower hesitancy, while exposure to anti-vaccine content was associated with higher hesitancy.

Key Contributions
The paper claims three primary contributions to the literature:

Theoretical Integration: It integrates Protection Motivation Theory, the affect heuristic, and risk perception theory into a unified affective-cognitive appraisal framework, moving beyond the separation of emotions and safety judgments.
Mechanism Clarification: It models perceived vaccine risk not merely as a parallel predictor but as a latent indirect pathway linking health-related fear to vaccine hesitancy. This explains why factual correction alone may be insufficient when fear shapes risk interpretation.
Experience-Based Heterogeneity: It identifies prior vaccination experience as a significant source of variation in the fear–risk–hesitancy pathway, suggesting that experiential knowledge may calibrate or weaken fear-based risk appraisals.

Significance and Claims
The author interprets these findings as evidence consistent with a theoretically specified correlational pathway, explicitly noting that the cross-sectional design precludes causal claims regarding temporal ordering. The study argues that vaccine hesitancy is not solely an information deficit but a product of how risk signals are emotionally encoded and cognitively appraised.

The paper posits that public health communication strategies must address both factual risk information and emotional uncertainty. Specifically, it suggests that for individuals without prior vaccination experience, communication should combine clear risk information with emotional reassurance, procedural transparency, and tailored support to build confidence. The findings support the view that in digital environments, where adverse-event narratives can be amplified, fear operates as an affective risk signal that alters the weighting of vaccine information. The study concludes that recognizing this affective-cognitive architecture is essential for designing interventions that reduce hesitancy in emotionally charged information environments.

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