New research published in Psychology & Health indicates that when people become fearful about vaccines, it can make them less willing to get vaccinated. This hesitancy, in turn, might lead individuals to embrace conspiracy theories about vaccines as a way to justify their decision to avoid immunization.

Vaccines are a cornerstone of modern medicine, credited with dramatically reducing the impact of numerous infectious diseases. They work by training the body’s immune system to recognize and fight off specific viruses and bacteria. Diseases like measles, influenza, human papillomavirus, and Coronavirus Disease 2019 can be effectively prevented or mitigated through vaccination. The World Health Organization estimates that vaccinations prevent millions of deaths each year, not only protecting vaccinated individuals but also reducing the spread of diseases to vulnerable populations.

Despite the clear benefits and widespread scientific consensus supporting vaccination, a significant level of reluctance, known as vaccine hesitancy, persists globally. The World Health Organization has identified vaccine hesitancy as a major global health challenge. Recent studies show that a considerable portion of the population remains hesitant about receiving vaccines, including those for Coronavirus Disease 2019 and routine childhood immunizations like the measles vaccine.

Understanding the reasons behind this hesitancy is essential for improving public health outcomes. One factor that researchers are exploring is the role of conspiracy theories, which often circulate misinformation about vaccines.

Conspiracy theories involve beliefs that powerful groups, such as governments or pharmaceutical companies, are secretly plotting for their own advantage. In the context of vaccines, these theories can include the idea that pharmaceutical companies are hiding dangerous side effects, that vaccines are tools for population control, or that the ineffectiveness of vaccines is being concealed for profit. Belief in such conspiracy theories has been linked to a decreased likelihood of engaging in healthy behaviors, including vaccination.

Previous studies have suggested that emotions can play a role in the acceptance of conspiracy theories. For instance, anxiety has been shown to increase belief in conspiracies. While anxiety generally relates to worries about uncertain future events, fear is a more immediate emotion triggered by a perceived threat. Many messages opposing vaccination often use fear-based appeals, but the direct impact of vaccine-related fear on hesitancy and conspiracy beliefs had not been thoroughly investigated.

To address this gap, a team of researchers led by Daniel Jolley at the University of Nottingham, along with colleagues from Northumbria University, conducted a series of studies to examine whether fear related to vaccines can contribute to the acceptance of conspiracy beliefs about vaccines.

“We were interested in understanding how emotions, particularly fear, influence people’s beliefs and decisions around vaccination,” said Jolley, an assistant professor in social Psychology at the University of Nottingham. “Given the rise of anti-vaccine conspiracy theories and vaccine hesitancy, especially during public health crises, it’s crucial to understand the psychological processes behind these attitudes. By exploring the emotional drivers, we hoped to shed light on how fear can shape people’s reasoning and, ultimately, their health-related choices.”

The researchers conducted three separate studies. In Study 1a, they recruited 221 participants online. The participants were divided into two groups. Both groups were given information about a fictitious new virus called Flebilis-Potentia and a vaccine to prevent it. This fictional scenario was used to study vaccine attitudes without raising ethical concerns related to real vaccines.

One group, the low fear group, read an expert opinion stating that people should not be afraid of the vaccine and that severe side effects were rare. The other group, the high fear group, read an expert opinion suggesting that people should feel fear toward the vaccine, although still noting that severe side effects were uncommon.

After reading this information, participants answered questions to ensure they understood the material. They then rated their fear of the vaccine, their belief in vaccine conspiracy theories using a standard questionnaire, and their intention to get vaccinated against Flebilis-Potentia.

In Study 1b, the researchers aimed to confirm the findings of Study 1a with a larger sample of 508 participants, using the same methods and materials.

The researchers designed Study 2 to further explore the relationship between vaccine hesitancy and conspiracy beliefs. In this study, all 220 participants were placed in the high fear condition, reading the expert opinion designed to induce fear about the vaccine. However, participants were then randomly assigned to one of two conditions related to vaccination intention.

One group was asked to consider reasons why they would want to get vaccinated, while the other group was asked to consider reasons why they would not want to get vaccinated. After this, participants again reported their intention to get vaccinated, their belief in vaccine conspiracy theories, and, in this study, also their sense of connection to people who distrust official accounts of events.

In analyzing the data from Study 1a, the researchers found that their manipulation of fear was successful. Participants in the high fear group reported significantly greater fear of the vaccine than those in the low fear group. Importantly, the high fear group also showed stronger belief in vaccine conspiracy theories and were less inclined to say they would get vaccinated compared to the low fear group. Statistical analysis indicated that fear seemed to increase conspiracy beliefs, which in turn decreased the intention to get vaccinated.

Interestingly, the researchers also explored whether fear might first reduce vaccination intention, and that this hesitancy then leads to increased conspiracy beliefs as a justification. They found evidence supporting this alternative pathway as well.

Study 1b largely confirmed the findings related to vaccine hesitancy. Participants in the high fear condition were again less inclined to get vaccinated. However, in this study, the direct link between fear and conspiracy beliefs was not statistically significant. Despite this, the researchers found support for the pathway where fear increased vaccine hesitancy, and this hesitancy was then linked to stronger conspiracy beliefs.

In Study 2, where all participants experienced high fear, the researchers found that those asked to consider reasons not to vaccinate reported lower vaccination intentions than those asked to consider reasons to vaccinate. While there was no direct effect of this manipulation on conspiracy beliefs or connection to people distrusting official narratives, further analysis revealed an indirect effect. Thinking about reasons not to vaccinate reduced vaccination intention, and this reduced intention was associated with stronger conspiracy beliefs and a greater sense of connection with those who distrust official accounts.

“The main takeaway is that fear can lead people to hesitate about vaccines, and this hesitancy can make conspiracy theories more appealing as a way to justify that initial emotional response,” Jolley told PsyPost. “It’s not just about what people believe but how they feel – managing fear and emotional responses could be key to improving vaccine uptake and reducing the spread of conspiracy beliefs.”

“We initially expected that fear would increase conspiracy beliefs first, which would then lead to vaccine hesitancy. Instead, we found a different pattern – fear seemed to directly provoke hesitancy, and conspiracy beliefs seem to emerge afterward, possibly as a way to rationalize the decision to avoid vaccination. This reversed pathway was unexpected and highlights how emotions could lead reasoning, rather than the other way around.”

But the study, like all research, has limitations.

“One major caveat is that establishing clear causal relationships was challenging,” Jolley noted. “While our exploratory mediation analysis offered insights into the process, further experimental work is needed to confirm the sequence of fear, vaccine hesitancy, and conspiracy beliefs. Additionally, emotional reactions are complex and influenced by many factors, which we couldn’t fully capture in our studies.”

Despite these limitations, the research provides valuable insights into the psychological factors that contribute to vaccine hesitancy. It highlights the important role of emotions, particularly fear, and how these emotions can interact with conspiracy beliefs to influence people’s willingness to get vaccinated.

“Moving forward, we aim to explore interventions that help people better regulate their emotions, particularly fear, when faced with health-related decisions,” Jolley explained. “If we can find ways to reduce fear-driven vaccine hesitancy, we may also lessen the appeal of conspiracy theories that stem from those emotions. Ultimately, our goal is to contribute to public health efforts by addressing the emotional roots of vaccine resistance and improving communication strategies.”

The study, “The fear factor: examining the impact of fear on vaccine hesitancy and anti-vaccine conspiracy beliefs,” was authored by Daniel Jolley, Lee Shepherd, and Anna Maughan.