Anti-vaccine Sentiment Research Articles

Russian Twitter Accounts and the Partisan Polarization of Vaccine Discourse, 2015-2017.

Objectives. To understand how Twitter accounts operated by the Russian Internet Research Agency (IRA) discussed vaccines to increase the credibility of their manufactured personas.Methods. We analyzed 2.82 million tweets published by 2689 IRA accounts between 2015 and 2017. Combining unsupervised machine learning and network analysis to identify "thematic personas" (i.e., accounts that consistently share the same topics), we analyzed the ways in which each discussed vaccines.Results. We found differences in volume and valence of vaccine-related tweets among 9 thematic personas. Pro-Trump personas were more likely to express antivaccine sentiment. Anti-Trump personas expressed support for vaccination. Others offered a balanced valence, talked about vaccines neutrally, or did not tweet about vaccines.Conclusions. IRA-operated accounts discussed vaccines in manners consistent with fabricated US identities.Public Health Implications. IRA accounts discussed vaccines online in ways that evoked political identities. This could exacerbate recently emerging partisan gaps relating to vaccine misinformation, as differently valenced messages were targeted at different segments of the US public. These sophisticated targeting efforts, if repeated and increased in reach, could reduce vaccination rates and magnify health disparities.

Modelling anti-vaccine sentiment as a cultural pathogen.

Culturally transmitted traits that have deleterious effects on health-related traits can be regarded as cultural pathogens. A cultural pathogen can produce coupled dynamics with its associated health-related traits, so that understanding the dynamics of a health-related trait benefits from consideration of the dynamics of the associated cultural pathogen. Here, we treat anti-vaccine sentiment as a cultural pathogen, modelling its 'infection' dynamics with the infection dynamics of the associated vaccine-preventable disease. In a coupled susceptible-infected-resistant (SIR) model, consisting of an SIR model for the anti-vaccine sentiment and an interacting SIR model for the infectious disease, we explore the effect of anti-vaccine sentiment on disease dynamics. We find that disease endemism is contingent on the presence of the sentiment, and that presence of sentiment can enable diseases to become endemic when they would otherwise have disappeared. Furthermore, the sentiment dynamics can create situations in which the disease suddenly returns after a long period of dormancy. We study the effect of assortative sentiment-based interactions on the dynamics of sentiment and disease, identifying a tradeoff whereby assortative meeting aids the spread of a disease but hinders the spread of sentiment. Our results can contribute to finding strategies that reduce the impact of a cultural pathogen on disease, illuminating the value of cultural evolutionary modelling in the analysis of disease dynamics.

Characterizing HPV Vaccine Sentiments and Content on Instagram.

Background. With its growing popularity, inclusion of image and text, and user-friendly interface, Instagram is uniquely positioned for exploring health behaviors and sources and types of informational exposure related to the human papillomavirus (HPV) vaccine. Aims. To characterize public Instagram posts about the HPV vaccine and quantify the impact of sentiment and context on engagement via likes. Method. Using Netlytic, 3,378 publicly available English-language posts were collected using the search terms "#HPV," "#HPVVaccine," and "#Gardasil." We randomly selected 1,200 posts to content analyze. Our final analytic sample included 360 posts after excluding posts whose links were no longer active (n = 221) or that were not relevant (n = 619). Results. A higher proportion of posts were pro-vaccine (55.8%) than anti-vaccine (42.2%). Pro-HPV vaccination posts were liked significantly less than anti-vaccination posts (24 vs. 86 likes; p < .001). More posts contained actionable information/resources (63.9%) than personal narrative elements (36.1%). Less than one in three posts (30.0%) came from health-related sources. Discussion. Pro-vaccine posts were more prevalent on Instagram, and anti-vaccine posts had higher engagement and typically included misleading information about the HPV vaccine. Personal narratives skewed toward anti-vaccine sentiments and most were produced by individual users. Pro-vaccine narratives portrayed individuals who received the vaccine, but provided limited details on vaccine experiences, starkly contrasting with the depth of details in anti-vaccine personal narrative posts. Conclusion. On Instagram, individuals and organizations have an opportunity to promote HPV vaccination by continuing to provide informational resources in addition to creating more narrative-style posts.

Role of Social Media in vaccination debate about HPV: the VAC Medi+Board study

Abstract Background Whilst it has long been known that anti-vaccination sentiment is widely disseminated through digital networks, 2019 has seen seismic shifts in the landscape. As viral videos originating on Youtube spread across social networks, HPV vaccine uptake tumbled in a number of countries. In Japan, the government came under sufficient pressure that they de-recommended HPV vaccine, seeing a 70% uptake rate in 2013 fall below 1%. However, there have been some reports of successful interventions - a recent campaign run by the HPV Alliance in Ireland has seen a rate back up to a national average of around 75%. A combination of hard-hitting personal testimonials, social media and traditional media looked to promote the HPV vaccine. Methods Social media platforms such as Twitter enable near real-time understandings of vaccine sentiment and information flows at scale. VAC Medi+Board project developed an innovative approach for Twitter data collection, integration, analysis and visualisation to support rapid responses through identifying key influencers and flashpoints in articles about vaccination going viral. Results This pilot study evaluated the debate about HPV on Twitter in a period of several month and developed methods for analysis and visualisation of the content, key influencers, information diffusion throughout the network and size of audience. Through complex network analysis, VAC Medi+Board piloted identification of individuals for targeted public health interventions to combat misinformation. Conclusions In this talk, we will present the VAC Medi+Board HPV study and explore the challenges and opportunities that social media can provide for public health policymakers. Key messages Analysis and graphical visualisation of HPV debate on Twitter to support targeted public health interventions at real-time. Contributing to better understanding the role of social media in the complex picture of vaccines hesitancy.

Role of Social Media in vaccination debate about HPV: the VAC Medi+Board study

Abstract Whilst it has long been known that anti-vaccination sentiment is widely disseminated through digital networks, 2019 has seen seismic shifts in the landscape. As viral videos originating on Youtube spread across social networks, HPV vaccine uptake tumbled in a number of countries. In Japan, the government came under sufficient pressure that they de-recommended HPV vaccine, seeing a 70% uptake rate in 2013 fall below 1%. However, there have been some reports of successful interventions - a recent campaign run by the HPV Alliance in Ireland has seen a rate back up to a national average of around 75%. A combination of hard-hitting personal testimonials, social media and traditional media looked to promote the HPV vaccine. Social media platforms such as Twitter enable near real-time understandings of vaccine sentiment and information flows at scale. VAC Medi+Board project developed an innovative approach for Twitter data collection, integration, analysis and visualisation to support rapid responses through identifying key influencers and flashpoints in articles about vaccination going viral. This pilot study evaluated the debate about HPV on Twitter in a period of several month and developed methods for analysis and visualisation of the content, key influencers, information diffusion throughout the network and size of audience. Through complex network analysis, VAC Medi+Board piloted identification of individuals for targeted public health interventions to combat misinformation. In this talk, we will present the VAC Medi+Board HPV study and explore the challenges and opportunities that social media can provide for public health policymakers.

A Systematic Review of Methods to Improve Attitudes Towards Childhood Vaccinations.

Although measles was eradicated in the United States in 2000, there has been an increasing number of cases. As of April 4, 2019, the Centers for Disease Control and Prevention (CDC) reported 465 cases of measles as compared to 372 in 2018. Pockets of unvaccinated communities and travelers bringing measles from countries with large outbreaks are attributed to the rise in cases in the United States. With the increasing anti-vaccine sentiment, it’s imperative to take preventative measures to avoid the proliferation of deadly diseases.The objective of this study was to determine effective techniques to decrease vaccine refusal and increase the childhood vaccination rate. To this effect, a systematic review of English peer-reviewed articles published in the years 2000 to 2019 using Arizona State University’s online database was conducted. The titles, abstracts, and discussions for each journal article were screened for methods that promote vaccination. Any articles that included vaccine development, promoting vaccination coverage rate in developing countries, pregnant women, healthcare workers, and animals, and promoting the uptake of vaccines that aren’t part of CDC’s seven-vaccine series were excluded.A total of nine journal articles were identified, including five systematic reviews, one case study, a randomized controlled trial, a literature review, and a quasi-experimental study. The methods discovered pertained to three themes: technological, mass marketing or campaigning, and direct communication. The Guide to Tailored Immunization Programme (TIP) in conjunction with visually enhanced educational materials and storytelling articles were found to be effective tools in encouraging vaccination coverage.The basis of any strategy is determining the perspective and needs of the target population and tailoring the approaches to match them to alleviate barriers that hinder vaccination uptake. The use of technology perpetuates the efficacy of social marketing strategies, further promoting vaccines and their benefits.

Mandate vaccination with care.

Governments that are considering compulsory immunizations must avoid stoking anti-vaccine sentiment, argue Saad B. Omer, Cornelia Betsch and Julie Leask. Governments that are considering compulsory immunizations must avoid stoking anti-vaccine sentiment, argue Saad B. Omer, Cornelia Betsch and Julie Leask.

THE VACCINE HESITANCY - THE NEW PLAGUE OF THE 21ST CENTURY

For the first time in 2019, the World health organization (WHO) anked non-vaccination among the top 10 threats to humanity. Immunprevention, initiated by E. Jenner in 1796, became one of the greatest achievements of medicine, which nowadays annually prevents up to 3 million human deaths. Despite this fact, in recent years, society is increasing anti-vaccination sentiment, frequent cases of refusal of vaccination. The population’s attitude to vaccination has been analyzed and the main reasons for its rejection have been identified. By means of anonymous online survey the study involved 954 participant in the age range from 18 to 70 years. Participants have different levels of education, live throughout Russia and make decisions for themselves and for children in the matter of vaccination. The widespread lack of information about the purpose of the vaccination, its complications and the vaccine controlled infection have been indicated. Actually, mothers are most vulnerable to doubts about their children’s vaccination - 115 women give up all vaccinations. Many respondents (59 respondents) point to distrust of doctors as a reason for refusal of vaccination. More over, adults are not aware of the need for revaccination at all. There are a significant lack of health education and public distrust of health workers. Finally, methods to increase the population’s commitment to vaccination have been developed, aimed to overcome unfounded fears about vaccination and to improve the status of health workers.

Examining Emergent Communities and Social Bots Within the Polarized Online Vaccination Debate in Twitter

Many states in the United States allow a “belief exemption” for measles, mumps, and rubella (MMR) vaccines. People’s opinion on whether or not to take the vaccine can have direct consequences in public health. Social media has been one of the dominant communication channels for people to express their opinions of vaccination. Despite governmental organizations’ efforts of disseminating information of vaccination benefits, anti-vaccine sentiment is still gaining momentum. Studies have shown that bots on social media (i.e., social bots) can influence opinion trends by posting a substantial number of automated messages. The research presented here investigates the communication patterns of anti- and pro-vaccine users and the role of bots in Twitter by studying a retweet network related to MMR vaccine after the 2015 California Disneyland measles outbreak. We first classified the users into anti-vaccination, neutral to vaccination, and pro-vaccination groups using supervised machine learning. We discovered that pro- and anti-vaccine users retweet predominantly from their own opinion group. In addition, our bot analysis discovers that 1.45% of the corpus users were identified as likely bots which produced 4.59% of all tweets within our dataset. We further found that bots display hyper-social tendencies by initiating retweets at higher frequencies with users within the same opinion group. The article concludes that highly clustered anti-vaccine Twitter users make it difficult for health organizations to penetrate and counter opinionated information while social bots may be deepening this trend. We believe that these findings can be useful in developing strategies for health communication of vaccination.

It’s not all about autism: The emerging landscape of anti-vaccination sentiment on Facebook

BackgroundDue in part to declining vaccination rates, in 2018 over 20 states reported at least one case of measles, and over 40,000 cases were confirmed in Europe. Anti-vaccine posts on social media may be facilitating anti-vaccination behaviour. This study aimed to systematically characterize (1) individuals known to publicly post anti-vaccination content on Facebook, (2) the information they convey, and (3) the spread of this content. MethodsOur data set consisted of 197 individuals who posted anti-vaccination comments in response to a message promoting vaccination. We systematically analysed publicly-available content using quantitative coding, descriptive analysis, social network analysis, and an in-depth qualitative assessment. The final codebook consisted of 26 codes; Cohen’s κ ranged 0.71–1.0 after double-coding. ResultsThe majority (89%) of individuals identified as female. Among 136 individuals who divulged their location, 36 states and 8 other countries were represented. In a 2-mode network of individuals and topics, modularity analysis revealed 4 distinct sub-groups labelled as “trust,” “alternatives,” “safety,” and “conspiracy.” For example, a comment representative of “conspiracy” is that poliovirus does not exist and that pesticides caused clinical symptoms of polio. An example from the “alternatives” sub-group is that eating yogurt cures human papillomavirus. Deeper qualitative analysis of all 197 individuals’ profiles found that these individuals also tended to post material against other health-related practices such as water fluoridation and circumcision. ConclusionsSocial media outlets may facilitate anti-vaccination connections and organization by facilitating the diffusion of centuries old arguments and techniques. Arguments against vaccination are diverse but remain consistent within sub-groups of individuals. It would be valuable for health professionals to leverage social networks to deliver more effective, targeted messages to different constituencies.

Expressions of pro- and anti-vaccine sentiment on YouTube

Billions of hours of YouTube content are viewed every day. Much of this content is aimed at entertainment, some of it is educational, and a considerable quantity is meant to influence or reinforce public opinion on a variety of matters, including health. Most of the content on YouTube is not created by professionals, public institutions or the traditional media, and instead is authored by private individual content creators. Given the potential impact of this medium for communicating health information, it is important for researchers and public health practitioners to understand the nature of health information as it is shared on YouTube. The primary objective of this research is to describe expressions of vaccine hesitancy content on YouTube, and specifically, compare the expression of pro- and anti-immunization sentiments. We do this by not only analyzing a systematic sample of influenza and measles immunization videos in terms of viewer analytics, but also by choice of language. We find that pro- and anti-immunization videos are common, but that videos with anti-immunization sentiment tend to be more ‘liked’. We also find that a small number of words can be effectively used to identify anti-immunization content, an observation that could be useful for identifying trends in anti-immunization sentiment on social media. Our results suggest that public health experts may need to increase the profile of their content on YouTube, and that there may be some useful strategies for improving the public's disposition towards pro-immunization messaging.

266. The Emerging Landscape of Anti-Vaccination Sentiment On Facebook

High levels of vaccination have been essential at curbing the rate of vaccine-preventable diseases and early deaths, yet an increasing number of individuals refuse vaccines for themselves or their children. Previous research suggests that anti-vaccination rhetoric on social media may serve to facilitate anti-vaccination behavior. However, the vast majority of this work has focused on Twitter or content on public social media pages (e.g. public Facebook groups). Therefore, this study aimed to characterize individuals known to publicly post anti-vaccination content on Facebook. Our dataset consisted of 197 individuals on Facebook who posted distinctly anti-vaccination comments on a prominent local pediatric clinic’s Facebook page. These comments were in response to a 90-second video that promoted the HPV vaccine as an anti-cancer vaccine, as recommended by the National Cancer Institute. In order to increase feasibility of quantitative double-coding and qualitative assessment, we obtained a random subsample of 25% of the 795 individuals who posted these comments, resulting in our dataset of 197 individuals. For each individual, we systematically analyzed publicly available content on their Facebook page over a two-year period (2015-2017) using quantitative coding of sociodemographic characteristics and anti-vaccination posts, social network analysis (SNA), and an in-depth qualitative analysis. Of the 197 individuals, 89% identified as female. There were 36 states and 8 countries listed across individuals that identified their location (n=136). Of the 116 individuals whose profile contained publicly viewable anti-vaccination posts during the time frame under analysis, the most frequent anti-vaccination topics were “educational material,” such as testimony from health professionals against vaccines (73%); “censorship and cover up,” alleging cover-up by organizations of adverse vaccine reactions (71%); and “vaccines cause idiopathic illnesses,” such as rashes or seizures (69%). For SNA, a two-mode network was constructed, and there were 1068 connections between individuals and topics. Modularity analysis found anti-vaccination topics and people tend to cluster into 4 sub-groups, each with a different primary reason for opposing vaccines: (1) emphasis on liberty, (2) focus on naturalness, (3) vaccine safety, and (4) conspiracy theories. Qualitative analysis revealed that many of these individuals use language that is consistent with the characteristics of science denialism. Individuals also post about other themes (e.g. alternative medicine, anti-genetically modified food) in ways that cluster into the subgroups identified through SNA. Examining the content of Facebook profiles known to post anti-vaccination content provides insight into the characteristics and beliefs of these individuals. Individuals who commented on the Facebook page of a pediatric practice located in a single U.S. city were based in locations around the globe, suggesting those against vaccination may be connecting in new ways via social media. Moreover, although the anti-vaccine movement has long been tied to autism, current arguments against vaccination are diverse, with individuals and anti-vaccination topics clustering into distinct subgroups. These findings suggest the need for health professionals to develop more effective interventions that reflect the beliefs of each subgroup to counter the anti-vaccination movement on social media.

Neighbourhood influence on the fourth dose of diphtheria-tetanus-pertussis vaccination.

Using 542,159 vaccination records from children born between April 1, 2007, and March 31, 2012, in the Michigan Care Improvement Registry and data from the American Community Survey, we determine if neighbourhood-level characteristics at the Census tract level and block level are associated with low uptake of the fourth dose of diphtheria-tetanus-acellular pertussis vaccine (DTaP4). This study was a cross-sectional study. We used exploratory factor analysis to determine important socio-economic factors at the Census block level and tract level. We then used generalised estimating equations to test the relationship between block- and tract-level socio-economic factors and DTaP4 uptake. DTaP4 coverage was 88.6% (95% confidence interval [CI]: 88.4%-88.7%) in Michigan. At the Census tract level, two factors surfaced as important for DTaP4 vaccination: 'affluence' (Cronbach's alpha=0.88) and 'socio-economic disadvantage' (Cronbach's alpha=0.89). At the Census block level, one factor was important: 'affluence' (Cronbach's alpha=0.90). Affluence may relate to knowledge about medical exemptions and antivaccination sentiment, while socio-economic disadvantage may indicate limited access to healthcare resources. Children in high-affluence tracts had 1.08% lower vaccination coverage (95% CI: -1.62% to -0.55%) than children in low affluence tracts. Children in low socio-economic disadvantage tracts had 2.92% higher coverage than children in high socio-economic disadvantage tracts (95% CI: 2.58%-3.26%). This study articulates the need to further understand the contribution of neighbourhood-level characteristics, from both affluent and socioeconomically disadvantaged areas to low vaccination rates. Developing a better understanding of these social environmental factors will help determine useful community-level interventions to improve vaccination rates and reduce disease burden.

User-Driven Comments on a Facebook Advertisement Recruiting Canadian Parents in a Study on Immunization: Content Analysis.

BackgroundMore people are searching for immunization information online and potentially being exposed to misinformation and antivaccination sentiment in content and discussions on social media platforms. As vaccination coverage rates remain suboptimal in several developed countries, and outbreaks of vaccine-preventable diseases become more prevalent, it is important that we build on previous research by analyzing themes in online vaccination discussions, including those that individuals may see without actively searching for information on immunization.ObjectiveThe study aimed to explore the sentiments and themes behind an unsolicited debate on immunization in order to better inform public health interventions countering antivaccination sentiment.MethodsWe analyzed and quantified 117 user-driven open-ended comments on immunization posted in the Comments section of a Facebook advertisement that targeted Canadian parents for recruitment into a larger study on immunization. Then, 2 raters coded all comments using content analysis.ResultsOf 117 comments, 85 were posted by unique commentators, with most being female (65/85, 77%). The largest proportion of the immunization comments were positive (51/117, 43.6%), followed by negative (41/117, 35.0%), ambiguous (20/117, 17.1%), and hesitant (5/117, 4.3%). Inaccurate knowledge (27/130, 20.8%) and misperceptions of risk (23/130, 17.7%) were most prevalent in the 130 nonpositive comments. Other claims included distrust of pharmaceutical companies or government agencies (18/130, 13.8%), distrust of the health care system or providers (15/130, 11.5%), past negative experiences with vaccination or beliefs (10/130, 7.7%), and attitudes about health and prevention (10/130, 7.7%). Almost 40% (29/74, 39%) of the positive comments communicated the risks of not vaccinating, followed by judgments on the knowledge level of nonvaccinators (13/74, 18%). A total of 10 positive comments (10/74, 14%) specifically refuted the link between autism and vaccination.ConclusionsThe presence of more than 100 unsolicited user-driven comments on a platform not intended for discussion, nor providing any information on immunization, illustrates the strong sentiments associated with immunization and the arbitrariness of the online platforms used for immunization debates. Health authorities should be more proactive in finding mechanisms to refute misinformation and misperceptions that are propagating uncontested online. Online debates and communications on immunization need to be identified by continuous monitoring in order for health authorities to understand the current themes and trends, and to engage in the discussion.

Tailoring immunisation programmes: Using behavioural insights to identify barriers and enablers to childhood immunisations in a Jewish community in London, UK

IntroductionDue to regular vaccine preventable disease outbreaks and sub-optimal immunisation uptake in the London borough of Hackney, home to the largest Charedi Orthodox Jewish community in Europe, it was decided, in consultation with the community, to implement the WHO Tailoring Immunization Programmes approach (TIP). DesignThe WHO Tailoring Immunization Programmes (TIP) approach was used. TIP provides a framework based on behavioural insights methodology to identify populations susceptible to vaccine preventable diseases, diagnose supply and demand side barriers and enablers to vaccination and recommend evidence-informed responses to improve vaccination coverage. ResultsThe results of the formative research and behavioural analysis challenged the assumption that a cultural or religious anti-vaccination sentiment existed within the community. Critical issues related to access to and convenience of immunisation services. Service providers in the area have challenges due to having to deliver immunisation services to the large numbers of children without additional resource. Where mothers were choosing to delay or refuse vaccinations their reasons were broadly similar to the wider population. The behavioural analysis identified potential categorisation of subgroups within the community enabling a more tailored approach to addressing concerns and meeting parents’ needs. ConclusionThe TIP approach was an effective way of investigating factors linked to sub-optimal immunisation within the Charedi community. The use of behavioural insights enabled the categorisation of subgroups so that more targeted interventions could be developed. The comprehensive stakeholder engagement which is a key pillar of the TIP approach ensured a deeper understanding of the barriers and enablers to vaccination as well as increasing the level of ownership in the community. TIP should be considered as a useful approach to identify main facilitators and barriers to vaccination in communities with suboptimal immunisation uptake.

A qualitative analysis of the beliefs of Japanese anti-influenza vaccination website authors

BackgroundInfluenza vaccine coverage among the Japanese population is less than optimal. Anti-vaccination sentiment exists worldwide, and Japan is no exception. Anti-influenza vaccination activists argue on the internet that influenza vaccine has little or no efficacy and a high risk of side effects, and they warn that people should forgo vaccination. We conducted a qualitative analysis to explore beliefs underlying the messages of anti-influenza vaccination websites, by focusing on the perceived value these beliefs provide to those who hold them. MethodsWe conducted online searches in January 2017 using two major Japanese search engines (Google Japan and Yahoo! Japan). Targeted websites were classified as “pro”, “anti”, or “neutral” depending on their claims. We applied a dual analytic approach—inductive thematic analysis and deductive interpretative analysis—to textual data of the anti websites. ResultsOf the 113 anti websites, we identified two themes that correspond to beliefs: it is necessary to 1) protect others against risks and exploitation related to influenza vaccination, and 2) educate others about hidden truths and self-determination. Authors of anti websites ascribed two values (people's “safety” and one's own “self-esteem”) to their beliefs. DiscussionWebsite authors may engage in anti-vaccination activities because they want to feel they are virtuous, saving people from harm caused by vaccination, and to boost their self-esteem, thinking “I am enlightening uninformed people.” The anti-vaccination beliefs of website authors were considered to be strong. In promoting vaccination, it would be better not to target outright vaccine refusers, such as the authors of anti-vaccination websites; it is preferable to target vaccine-hesitant people who are more amenable to changing their attitudes toward vaccination. We discuss possible means of promoting vaccination in that target population.

Internet Exposure Associated With Canadian Parents' Perception of Risk on Childhood Immunization: Cross-Sectional Study.

BackgroundThere is a large presence of provaccination and antivaccination content on the Internet. The Internet has been identified as an important source for parents to seek and share vaccine information. There are concerns that parental fears or hesitancy on childhood immunizations are increasing due to the popularity of social media and exposure to online antivaccination sentiment. No other studies have investigated the association between seeking vaccine information online and Canadian parents’ perception of risk on childhood immunization.ObjectiveWe aimed to investigate the potential association between seeking vaccine information on the Internet and Canadian parents’ perception of risk on childhood immunization in order to quantify the perceived association and increase our understanding on the impact of the Internet to help guide public health interventions.MethodsWe analyzed this association in two population samples: a self-selecting Web-based sample of Canadian parents recruited through Facebook (n=966) and a population-based sample of parents recruited by random digit dialing (RDD; n=951). The outcome was parental perception of vaccine safety on a seven-point ordinal scale from “not safe” to “extremely safe.” An ordinal regression model was used to investigate if Internet information seeking on childhood vaccination predicted parental perception of vaccine safety.ResultsAfter adjusting for income level, Internet reliability, age of parent, and region, the odds of perceiving vaccines as less safe rather than more safe were 1.6 times higher (95% CI 1.3-2.1) for parents who used the Internet to search for vaccination information compared to parents who did not search the Internet in the Web-based sample, and 2.0 times higher (95% CI 1.6-2.5) in the population-based RDD sample.ConclusionsThe results suggest the Internet is significantly associated with Canadian parents’ negative perception of vaccine risk. Governmental and scientific sectors should consider the development and implementation of Web-based vaccine interventions to promote confidence in immunization.

An agent-based model of school closing in under-vaccinated communities during measles outbreaks

The winter 2014-15 measles outbreak in the US represents a significant crisis in the emergence of a functionally extirpated pathogen. Conclusively linking this outbreak to decreases in the measles/mumps/rubella (MMR) vaccination rate (driven by anti-vaccine sentiment) is critical to motivating MMR vaccination. We used the NOVA modeling platform to build a stochastic, spatially-structured, individual-based SEIR model of outbreaks, under the assumption that R0 ≈ 7 for measles. We show this implies that herd immunity requires vaccination coverage of greater than approximately 85%. We used a network structured version of our NOVA model that involved two communities, one at the relatively low coverage of 85% coverage and one at the higher coverage of 95%, both of which had 400-student schools embedded, as well as students occasionally visiting superspreading sites (e.g. high-density theme parks, cinemas, etc.). These two vaccination coverage levels are within the range of values occurring across California counties. Transmission rates at schools and superspreading sites were arbitrarily set to respectively 5 and 15 times background community rates. Simulations of our model demonstrate that a 'send unvaccinated students home' policy in low coverage counties is extremely effective at shutting down outbreaks of measles.

A readability comparison of anti- versus pro-influenza vaccination online messages in Japan.

Historically, anti-vaccination sentiment has existed in many populations. Mass media plays a large role in disseminating and sensationalizing vaccine objections, especially via the medium of the Internet. Based on studies of processing fluency, we assumed that anti-influenza vaccination online messages to be more readable and more fluently processed than pro-influenza vaccination online messages, which may consequently sway the opinions of some audiences. The aim of this study was to compare readability of anti- and pro-influenza vaccination online messages in Japan using a measure of readability.Web searches were conducted at the end of August 2016 using two major Japanese search engines (Google.jp and Yahoo!.jp). The included websites were classified as “anti”, “pro”, or “both” depending on the claims, and “health professional” or “non-health professional” depending on the writers' expertise. Readability was determined using a validated measure of Japanese readability (the Japanese sentence difficulty discrimination system). Readability of “health professional” websites was compared with that of “non-health professional” websites, and readability of “anti” websites was compared with that of “pro” websites, using the t-test.From a total of 145 websites, the online messages written by non-health professionals were significantly easier to read than those written by health professionals (p = 0.002, Cohen's d = 0.54). Anti-influenza vaccination messages were significantly easier to read than pro-influenza vaccination messages (p < 0.001, Cohen's d = 0.74).When health professionals prepare pro-influenza vaccination materials for publication online, we recommend they check for readability using readability assessment tools and improve the text for easy reading if necessary.

What makes anti-vaccine websites persuasive? A content analysis of techniques used by anti-vaccine websites to engender anti-vaccine sentiment

Anti-vaccine sentiment can be extremely resistant to change, making it difficult to promote childhood vaccines. Thus, there is a need for effective strategies to communicate the benefits of vaccination to vaccine hesitant parents. Understanding how anti-vaccine advocates successfully persuade parents against vaccinating their children can provide insight into communication tactics that could be incorporated into vaccine promotion efforts. The internet is an important source of vaccine information for many parents, and plays a role informing vaccine hesitancy. To understand what might make anti-vaccine websites so convincing, we used persuasion theory as a lens to examine what information was being presented, and the persuasive tactics being used to communicate the information. We conducted a content analysis of 480 anti-vaccine websites. Four trained coders coded sites for the content of the vaccine information being presented, types of persuasive tactics used, and values and lifestyle norms associated with anti-vaccine advocacy. Anti-vaccine websites contain a considerable amount of misinformation, most commonly that vaccines are dangerous, cause autism and brain injury. Websites used both scientific evidence and anecdotes to support these claims. Values such as choice, freedom, and individuality were linked to anti-vaccine beliefs. The most commonly co-promoted behaviors included the use of alternative medicine and homeopathy, and eating a healthy or organic diet. Anti-vaccine websites use a battery of effective persuasive techniques to forward their agenda. The use of similar persuasive techniques and tapping into parents’ values and lifestyles are potentially useful strategies for vaccine promotion communication.