Background Social media platforms such as YouTube are hotbeds for the spread of misinformation about vaccines. Objective The aim of this study was to explore how individuals are exposed to antivaccine misinformation on YouTube based on whether they start their viewing from a keyword-based search or from antivaccine seed videos. Methods Four networks of videos based on YouTube recommendations were collected in November 2019. Two search networks were created from provaccine and antivaccine keywords to resemble goal-oriented browsing . Two seed networks were constructed from conspiracy and antivaccine expert seed videos to resemble direct navigation . Video contents and network structures were analyzed using the network exposure model. Results Viewers are more likely to encounter antivaccine videos through direct navigation starting from an antivaccine video than through goal-oriented browsing. In the two seed networks, provaccine videos, antivaccine videos, and videos containing health misinformation were all found to be more likely to lead to more antivaccine videos. Conclusions YouTube has boosted the search rankings of provaccine videos to combat the influence of antivaccine information. However, when viewers are directed to antivaccine videos on YouTube from another site, the recommendation algorithm is still likely to expose them to additional antivaccine information.

BACKGROUND Social media platforms such as YouTube are hotbeds for the spread of misinformation about vaccines. OBJECTIVE To explore how individuals are exposed to anti-vaccine misinformation on YouTube. METHODS Four networks of videos based on YouTube recommendations were collected in November 2019. Two search networks were created from pro- and anti-vaccine keywords to resemble goal-oriented browsing. Two seed networks were constructed from conspiracy and anti-vaccine expert seed videos to resemble direct navigation. Video contents and network structures were analyzed using the Network Exposure Model. RESULTS Viewers are more likely to encounter anti-vaccine videos through direct navigation starting from an anti-vaccine video than through goal-oriented browsing. In the two seed networks, pro-vaccine videos, anti-vaccine videos, and videos containing health misinformation are all likely to lead to more anti-vaccine videos. CONCLUSIONS YouTube has boosted the search rankings of pro-vaccine videos to diminish the influence of anti-vaccine information. However, when viewers are directed to anti-vaccine videos on YouTube from another site, the recommendation algorithm is still likely to expose them to additional anti-vaccine information.

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African Americans in the United States have been disproportionately affected by the COVID-19 pandemic in infection and mortality rates. This study examined how middle-aged and older African American individuals accessed and evaluated the information about COVID-19. Semi-structured interviews with 20 individuals (age: 41–72) were conducted during the first stay-at-home advisory period in late March and early April 2020. The phronetic iterative approach was used for data analysis. We found that these individuals primarily relied on information scanning based on their routine media consumption to acquire information about COVID-19 and seldom actively searched for information outside of their regular media use. Individuals used several strategies to assess the quality of the information they received, including checking source credibility, comparing multiple sources, fact-checking, and praying. These findings could inform media and governmental agencies' future health communication efforts to disseminate information about the COVID-19 pandemic and future infectious disease outbreaks among the African American communities.