The Sources and Correlates of Exposure to Vaccine-Related (Mis)information Online

"These results indicate that both prior attitudes and online information sources play an important role in the online information that Americans consume about vaccines, providing an important pre-COVID baseline for the amount and type of vaccine information that people consume online."

Exposure to information online that questions the safety and effectiveness of vaccines may exacerbate vaccine hesitancy and be difficult to refute - an especially important risk to understand in the context of expected future vaccines during the global COVID-19 pandemic. The present study seeks to unearth what vaccine-related information people actually see online and the means by which they are exposed to it. To do so, the researchers analyse survey and linked online behavioural data from 7 large nationally representative samples collected in the United States (US) from October 2016 to February 2019.

The behavioural data consists of a stream of URLs visited by 7,320 YouGov survey panelists on their desktop and laptop computers during the period around each of the national surveys, constituting more than 134 million pageviews. The researchers also measured prior vaccine attitudes for 1,250 respondents for whom such measures are available.

In short, the researchers estimate that approximately 84% of Americans visit a vaccine-related webpage each year. However, visits to vaccine-related webpages are not common; the distribution is instead heavily skewed due to high levels of exposure among a small subset of respondents. Encounters with vaccine-skeptical content make up only 7.5% of vaccine-related pageviews and are encountered by only 18.5% of people annually. However, these pages are more likely to be published by untrustworthy sources.

Many observers fear that people with strong views or misinformed beliefs will become trapped in "echo chambers" of like-minded sources online. The study found that people with more favourable attitudes toward vaccines were relatively more likely to be exposed to less skeptical information about the topic, which could be the result of people with more favourable attitudes seeking pro-attitudinal information, people with less favourable attitudes avoiding counter-attitudinal information, or some combination of the two.

Finally, the research considers the role of social media platforms, search engines, and email - "online intermediaries" - in exposure to vaccine-related webpages and the extent to which their use is associated with the consumption of vaccine-skeptical information. Google use is differentially associated with subsequent exposure to non-skeptical content: Visits to Google immediately preceded 11.2% of visits to non-skeptical webpages related to vaccines compared with 6.3% of vaccine-skeptical webpages and 3.1% of unrelated content. In contrast, exposure to vaccine-skeptical webpages is associated with usage of webmail (e.g., Gmail) and, to a lesser extent, Facebook.

Reflecting on the results, the researchers envision unfulfilled opportunities for platforms to promote accurate information about vaccines. Platforms could better promote incidental exposure to accurate information (e.g., via Facebook's COVID-19 Information Center or Google's COVID-19 information dashboard). They conclude by stressing the need to "remain vigilant in monitoring the quality of vaccine-related information on the online platforms that now shape Americans' information diets, especially as COVID-19 vaccine candidates approach regulatory approval."