Vaccine Hesitancy and Online Information: The Influence of Digital Networks

"What kind of information will a parent who browses the Web for vaccine information get, and from what perspective? Once misinformation is found, how hard might it be to find better information?"

In 2012, the World Health Organization (WHO) Strategic Advisory Group of Experts (SAGE) working group was appointed to address vaccine hesitancy. This article focuses on the SAGE working group's "confidence" hesitancy group, for whom trust in the evidence supporting vaccinations plays an important role. These parents tend to rely on their own research to make vaccination decisions; thus, their media environments are of particular importance. This study explored the structure and influence of vaccine-hesitant content online by generating a database and network analysis of vaccine-relevant content. The goal was to identify influential publishers and the pattern of information spread within the vaccine-hesitant community, with a focus on comparing the traditional modes of authority used by scientific academia, by mainstream media, and by crowd platforms within the network.

In a United States (US) context, the researchers used Media Cloud, a searchable big-data platform of over 550 million stories from 50,000 media sources, for quantitative and qualitative study of an online media sample based on keyword selection. They generated a hyperlink network graph and measured indegree centrality of the sources and vaccine sentiment for a random sample of 450 stories. The researchers suggest thinking of this graph (see above) as a map of the content available for a user to navigate as she or he follows a series of links from one Web page to another, having started from some given point in the network. In this sense, the link network acts as the architecture within which users must make decisions about how to find and make sense of conflicting information about vaccination.

Among the 28,122 publications from 4,817 sources that met inclusion criteria, it was found that clustered communities formed based on shared hyperlinks: Communities tended to link within, not among, each other. The separation between the vaccine-hesitant and mainstream media communities on the map indicates that sources within these communities are only rarely interacting with one another through hyperlinks. Most link interaction between communities happens between the mainstream media and the provaccine and health and science communities, between the provaccine and the health and science communities, and between the vaccine-hesitant and the provaccine and health and science communities. The vaccine-hesitant community rarely interact with provaccine content and simultaneously use primary provaccine content within vaccine-hesitant narratives.

The plurality of information was provaccine (46.44%, 95% confidence interval, or CI [39.86%, 53.20%]). Of the 93 coded stories in the mainstream media link community, 66.67% were provaccine (95% CI [54.94%, 78.40%]). Of all the anti-vaccine stories in the coded sample set, 70.21% were within the vaccine-hesitant community (95% CI [54.61%, 85.81%]), even though that community included only 30.48% of the stories in the community detection.

The most influential sources were in the health community (National Institutes of Health (NIH), Centers for Disease Control and Prevention, or CDC) or mainstream media (New York Times); some user-generated sources also had strong influence and were provaccine (Wikipedia).

In short, the data show that:

• Antivaccine content is already uncommon online.
• The majority of that uncommon antivaccine content is published within the vaccine-hesitant community.
• Antivaccine content is especially uncommon in mainstream media.
• The vaccine-hesitant community shows strongly clustered linking behaviour toward itself.
• The vaccine-hesitant community remains robust while commonly linking to primary research content.

More on the latter point: Scientific evidence online drives vaccine information outside of the vaccine-hesitant community but is also prominently used and misused within the robust vaccine-hesitant community. The researchers conjecture that the abundance of direct links to the NIH's National Database for Biotechnology Information (NCBI) abstracts is useful within the vaccine-hesitant community precisely because academic papers are so technical and specific. In addition, the full papers are often not available, making it easier to include an abstract, minus any study limitations, as a method for backing a vaccine-hesitant narrative.

On the other hand, Wikipedia offers a contrasting mode of crowd-based authority. It entails making content both accessible to the lay reader and useful for providing high-level context to specific issues. This may explain the prevalence of links to Wikipedia articles within the provaccine community. None of the provaccine sources makes inroads within the vaccine-hesitant community, but the Wikipedia stories at least seem more resistant to misuse by the vaccine-hesitant community than individual abstracts on NCBI.

In conclusion, a crowd-based mode of authority that provides easily understandable, contextualised information about vaccines may be more effective at distributing provaccine messages than the current mode of relying on the authority of decontextualised and often pay-walled scientific papers.