This article investigates the issues of vaccine hesitancy and shaming, which arose in response to the implementation of World Health Organization (WHO) COVID-19 recommendations, on the social media platform of TikTok. By extending appraisal theory to include the use of visual attitudinal appraisals, the study examines the semiotic resources employed by TikTok users within the overarching context of the pandemic. A total of 254 videos expressing pro- and anti-vaccination viewpoints, posted by American and Australian users between 1 January 2021 and 31 January 2022, were extracted from the social network and subjected to a computer-assisted analysis. The study shows that vaccine hesitancy on the social networking service (SNS) is fuelled by the echo chamber effect, while any vaccine shaming on the platform may be seen as conspicuous virtue-signalling. The speakers’ evaluative language is mostly positive, since their main objective is to elicit the approval of members belonging to the same sub-cultural group. A few suggestions are made to reduce the impact of echo chambers and to encourage scientific literacy among TikTok users.