This article explores pre-Covid-19 vaccine sentiment through pro-vaccine (pro-vaxx) internet memes with a focus on anti-vaxx mom and Karen figures. We argue that pro-vaxxers on the popular social news aggregate site Reddit employed Karen and other variations on the anti-vaxx mom as a subversion of the mother warrior figure originally meant to be empowering for vaccine sceptics. While anti-vaxx mom and Karen memes were humorous and participatory, they also presented vaccine attitudes in moralistic and reductive terms via the mother valour/blame binary. The study allows us to understand a trajectory of modern vaccine hesitancy and responses to it leading up to Covid-19. Moreover, it explores the emergence of the Karen figure as a manifestation of moral outrage and indicative of broader struggles related to authoritative knowledge.