PurposeThis study uses third-person effect theory to examine the mechanisms of public opinion about self-regulatory efforts to deal with COVID-19 vaccine-related misinformation on social media, focusing on the roles of social undesirability perceptions and misinformation beliefs.Design/methodology/approachA national survey of 600 US adults from the Qualtrics panel was conducted. The study examines how perceived social desirability and misinformation beliefs moderate the relationship between exposure to misinformation and behavioral responses.FindingsThe results show that the perceived disparity in misinformation exposure relates to third-person perception (TPP), which increases support for content moderation and intentions for corrective actions. Perceiving misinformation as socially undesirable strengthens the link between the exposure gap and TPP. Individual beliefs about misinformation are identified as a crucial moderator, reducing the TPP effect on those who have high misinformation beliefs, leading to less support for content moderation and corrective actions.Originality/valueThis research enhances understanding of TPP in the context of COVID-19 vaccine misinformation by highlighting how social undesirability perceptions and misinformation beliefs moderate this effect. It emphasizes the significance of personal misinformation beliefs in shaping attitudes toward content moderation and corrective actions.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/OIR-04-2024-0220