Cornelia Betsch

The Influence of Vaccine-critical Websites on Perceiving Vaccination Risks

This large-scale Internet-experiment tests whether vaccine-critical pages raise perceptions of the riskiness of vaccinations and alter vaccination intentions. We manipulated the information environment (vaccine-critical website, control, both) and the focus of search (on vaccination risks, omission risks, no focus). Our analyses reveal that accessing vaccine-critical websites for five to 10 minutes increases the perception of risk of vaccinating and decreases the perception of risk of omitting vaccinations as well as the intentions to vaccinate. In line with the ‘risk-as-feelings’ approach, the affect elicited by the vaccine-critical websites was positively related to changes in risk perception.

Opportunities and challenges of Web 2.0 for vaccination decisions

A growing number of people use the Internet to obtain health information, including information about vaccines. Websites that allow and promote interaction among users are an increasingly popular source of health information. Users of such so-called Web 2.0 applications (e.g. social media), while still in the minority, represent a growing proportion of online communicators, including vocal and active anti-vaccination groups as well as public health communicators. In this paper, the authors: define Web 2.0 and examine how it may influence vaccination decisions; discuss how anti-vaccination movements use Web 2.0 as well as the challenges Web 2.0 holds for public health communicators; describe the types of information used in these different settings; introduce the theoretical background that can be used to design effective vaccination communication in a Web 2.0 environment; make recommendations for practice and pose open questions for future research. The authors conclude that, as a result of the Internet and Web 2.0, private and public concerns surrounding vaccinations have the potential to virally spread across the globe in a quick, efficient and vivid manner. Web 2.0 may influence vaccination decisions by delivering information that alters the perceived personal risk of vaccine-preventable diseases or vaccination side-effects. It appears useful for public health officials to put effort into increasing the effectiveness of existing communication by implementing interactive, customized communication. A key step to providing successful public health communication is to identify those who are particularly vulnerable to finding and using unreliable and misleading information. Thus, it appears worthwhile that public health websites strive to be easy to find, easy to use, attractive in its presentation and readily provide the information, support and advice that the searcher is looking for. This holds especially when less knowledgeable individuals are in need of reliable information about vaccination risks and benefits.

The Influence of Narrative v. Statistical Information on Perceiving Vaccination Risks

Background. Health-related information found on the Internet is increasing and impacts patient decision making, e.g. regarding vaccination decisions. In addition to statistical information (e.g. incidence rates of vaccine adverse events), narrative information is also widely available such as postings on online bulletin boards. Previous research has shown that narrative information can impact treatment decisions, even when statistical information is presented concurrently. Objectives. As the determinants of this effect are largely unknown, we will vary features of the narratives to identify mechanisms through which narratives impact risk judgments. Methods. An online bulletin board setting provided participants with statistical information and authentic narratives about the occurrence and nonoccurrence of adverse events. Experiment 1 followed a single factorial design with 1, 2, or 4 narratives out of 10 reporting adverse events. Experiment 2 implemented a 2 (statistical risk 20% vs. 40%) × 2 (2/10 vs. 4/10 narratives reporting adverse events) × 2 (high vs. low richness) × 2 (high vs. low emotionality) between-subjects design. Dependent variables were perceived risk of side-effects and vaccination intentions. Results. Experiment 1 shows an inverse relation between the number of narratives reporting adverse-events and vaccination intentions, which was mediated by the perceived risk of vaccinating. Experiment 2 showed a stronger influence of the number of narratives than of the statistical risk information. High (vs. low) emotional narratives had a greater impact on the perceived risk, while richness had no effect. Implications. The number of narratives influences risk judgments can potentially override statistical information about risk.

Präferenz für Intuition und Deliberation (PID)

Zusammenfassung: Personen unterscheiden sich darin, ob sie bevorzugt intuitiv oder reflektiv entscheiden (Epstein et al., 1996). Um diese individuellen Unterschiede zu erfassen, wurde ein neues Fragebogenmas konstruiert, das auf zwei unabhangigen Skalen die Praferenz fur Intuition bzw. die Praferenz fur Deliberation misst. Intuition wird hier, anders als bei Epstein, nicht als heuristisch-affektiver Modus verstanden, sondern als ein rein affektiver Modus. Deliberation ist konzipiert als reflektiver, kognitionsbasierter Modus. In drei Studien wird die Konstruktion, Uberprufung der Zweidimensionalitat und Validierung der Skala anhand von insgesamt uber 2500 Versuchspersonen berichtet. In einer konfirmatorischen Faktorenanalyse werden Fitindizes von GFI = .88, RMSEA = .09 erreicht. Praferenz fur Intuition korreliert positiv mit schnellem Entscheiden, Extraversion und Vertraglichkeit und ist unabhangig von der Fahigkeit zu logischem Denken. Praferenz fur Deliberation korreliert mit Gewissenhaftigkeit, Perfekt...

Barriers of Influenza Vaccination Intention and Behavior – A Systematic Review of Influenza Vaccine Hesitancy, 2005 – 2016

Background Influenza vaccine hesitancy is a significant threat to global efforts to reduce the burden of seasonal and pandemic influenza. Potential barriers of influenza vaccination need to be identified to inform interventions to raise awareness, influenza vaccine acceptance and uptake. Objective This review aims to (1) identify relevant studies and extract individual barriers of seasonal and pandemic influenza vaccination for risk groups and the general public; and (2) map knowledge gaps in understanding influenza vaccine hesitancy to derive directions for further research and inform interventions in this area. Methods Thirteen databases covering the areas of Medicine, Bioscience, Psychology, Sociology and Public Health were searched for peer-reviewed articles published between the years 2005 and 2016. Following the PRISMA approach, 470 articles were selected and analyzed for significant barriers to influenza vaccine uptake or intention. The barriers for different risk groups and flu types were clustered according to a conceptual framework based on the Theory of Planned Behavior and discussed using the 4C model of reasons for non-vaccination. Results Most studies were conducted in the American and European region. Health care personnel (HCP) and the general public were the most studied populations, while parental decisions for children at high risk were under-represented. This study also identifies understudied concepts. A lack of confidence, inconvenience, calculation and complacency were identified to different extents as barriers to influenza vaccine uptake in risk groups. Conclusion Many different psychological, contextual, sociodemographic and physical barriers that are specific to certain risk groups were identified. While most sociodemographic and physical variables may be significantly related to influenza vaccine hesitancy, they cannot be used to explain its emergence or intensity. Psychological determinants were meaningfully related to uptake and should therefore be measured in a valid and comparable way. A compendium of measurements for future use is suggested as supporting information.

Effect of Narrative Reports about Vaccine Adverse Events and Bias-Awareness Disclaimers on Vaccine Decisions: A Simulation of an Online Patient Social Network

Background. As the number of individuals who search for health information in interactive online environments is increasing, patient networks deserve more scientific attention. Objective. To quantitatively examine if and how reading statistical and/or narrative information as typically displayed in patient networks (e.g., patientslikeme.com) affects decisions for pharmaceuticals. Previous work suggests that narrative information (e.g., about vaccine adverse events, VAE) affects risk perceptions and intentions. The authors compare the effect of narrative and statistical information about VAE on vaccination decisions and examine if a disclaimer reduces the narrative bias as well as if low numeracy leads to increased use of the narratives. Method and Design. In an online experiment, 458 participants were randomly assigned to a 3 (relative frequency of vaccine adverse events in 1, 7, or 17 of 20 cases) × 3 (type of information: narratives, summary statistics, or both) × 2 (bias awareness v. control disclaimer) between-subjects design. Measurements. Perceived risk, vaccination intention, and subjective numeracy. Results. A higher relative frequency of cases reporting VAE decreased the intention to get vaccinated. This relation was mediated by increased risk perception. The type of information moderated the contents’ impact: Summary statistics had the smallest impact, whereas narrative information was more influential, and the presence of both types of information had the greatest impact on risk perception. Individuals who received the bias-awareness disclaimer were less influenced by the patient network. Highly numerate individuals were generally more sensitive to the provided information independent of its format. Conclusions. Patient networks can influence vaccination decisions by delivering risk-related information. Disclaimers may help to reduce the influence if desired.

Dr. Jekyll or Mr. Hyde? (How) the Internet influences vaccination decisions: Recent evidence and tentative guidelines for online vaccine communication

A growing number of people use the Internet to obtain ealth information, including information about vaccines. Webites promoting interaction among users are becoming increasingly opular. Users of these so-called Web 2.0 applications (e.g. social edia, online discussion boards, etc.) comprise not only consumers ooking for information (e.g. about a certain vaccine) but also public ealth communicators and active, vocal anti-vaccination groups. ven though it is a well known fact that an increasing number f Internet users search the Internet for health information [1,2], everal black boxes exist in terms of the interplay between Interet users, the World Wide Web and vaccination decisions [3]: ho accesses vaccination information websites? Which sources re searched for? Who contributes to online discussion boards? hat is the quality of information obtained on the Internet? What akes anti-vaccination messages so intuitively appealing? What trategies can or should be used online to actively support vaccinaion decisions? Is the Internet a source that supports or discourages pro-vaccination decision? Obviously, it is difficult to provide definitive answers to these uestions. Nevertheless, the aim of the current special issue is to egin opening the black boxes and extend the evidence base. We ssume that by unraveling the mysteries surrounding the Internet s a Dr. Jekyll or Mr. Hyde will allow tentative conclusions about nline vaccine communication strategies.1 The articles of this special issue cluster in the following secions: The first section takes a meta-perspective on the Internet nd its development towards Web 2.0. It defines and explains the eb terminology and outlines the potential impact of the Interet and specifically of Web 2.0 on vaccination decisions. Potential pportunities and challenges for health communicators as well as he individual user are in the focus. The second section examines he online information search as well as the processing of obtained nformation. It provides some evidence regarding the types of ources that can be found online, their quality, and their eventual ffect on vaccination decisions. The final section aids in the design f online vaccine communication and advocacy in a ‘minefield’, i.e. n an environment in which best evidence stands pari passu to antiaccination movements who disseminate (mis-)information. As an

Using Behavioral Insights to Increase Vaccination Policy Effectiveness

Even though there are policies in place, and safe and effective vaccines available, almost every country struggles with vaccine hesitancy, that is, a delay in acceptance or refusal of vaccination. Consequently, it is important to understand the determinants of individual vaccination decisions to establish effective strategies to support the success of country-specific public health policies. Vaccine refusal can result from complacency, inconvenience, a lack of confidence, and a rational calculation of pros and cons. Interventions should, therefore, be carefully targeted to focus on the reason for non-vaccination. We suggest that there are several interventions that may be effective for complacent, convenient, and calculating individuals whereas interventions that might be effective for those who lack confidence are scarce. Thus, efforts should be concentrated on motivating the complacent, removing barriers for those for whom vaccination is inconvenient, and adding incentives and additional utility for the calculating. These strategies might be more promising, economic, and effective than convincing those who lack confidence in vaccination.

The Measurement of Subjective Probability: Evaluating the Sensitivity and Accuracy of Various Scales

The RISK of an event generally relates to its expected severity and the perceived probability of its occurrence. In RISK research, however, there is no standard measure for subjective probability estimates. In this study, we compared five commonly used measurement formats--two rating scales, a visual analog scale, and two numeric measures--in terms of their ability to assess subjective probability judgments when objective probabilities are available. We varied the probabilities (low vs. moderate) and severity (low vs. high) of the events to be judged as well as the presentation mode of objective probabilities (sequential presentation of singular events vs. graphical presentation of aggregated information). We employed two complementary goodness-of-fit criteria: the correlation between objective and subjective probabilities (sensitivity), and the root mean square deviations of subjective probabilities from objective values (accuracy). The numeric formats generally outperformed all other measures. The severity of events had no effect on the performance. Generally, a rise in probability led to decreases in performance. This effect, however, depended on how the objective probabilities were encoded: pictographs ensured perfect information, which improved goodness of fit for all formats and diminished this negative effect on the performance. Differences in performance between scales are thus caused only in part by characteristics of the scales themselves-they also depend on the process of encoding. Consequently, researchers should take the source of probability information into account before selecting a measure.

Parents Trust Other Parents Lay Vaccination Narratives on the Web May Create Doubt about Vaccination Safety

In their editorial, Brown and Sevdalis 1 discuss the recent finding by Betsch and colleagues that lay narratives from the Internet reporting vaccine adverse events bias risk judgments despite concurrently presented, more reliable statistical information. The authors assert that this narrative bias need not raise concern regarding real-life vaccination decisions because parents are not likely to consult the Internet for health information as long as they are satisfied with the information they receive from official sources. We agree with this notion but would like to offer a differing conclusion, with markedly different implications regarding the appropriate level of concern about lay narratives on the Internet. Although in surveys many parents name their health care providers as the most common source of health information, focus groups and in-depth interviews reveal that parents often feel underinformed and indeed lack relevant vaccination knowledge. In such situations, they frequently prefer to turn to the Internet rather than to their health care providers for more information. Qualitative studies reveal thatwith regard to vaccination information, parents tend to distrust official government statements as well as their doctors, whom they view to be unduly influenced by the authorities. When directly asked for trusted sources of information, very few parents actually name the Internet (4%). However, it does provide one type of information that they seem to unanimously view as trustworthy: the experiences of other parents, often expressed in vivid narratives. Parents are seen to have no agenda and no reason to fabricate information. In sum, the literature suggests that parents do consult the Internet for vaccination information, especially when they are unsatisfied with the information at hand and uncertain about their decisions, which is often found to be the case. The Internet provides easy access to a large number of narrative reports about vaccine adverse events, authored by other parents. Accordingly, although we agree with Brown and Sevdalis about the conditions that would lead lay vaccinationnarratives on theWeb to be a serious cause for concern, we believe those very conditions are prevalent.