Anti-vaccine activism during the COVID-19 pandemic often united radical actors from opposite ends of the political spectrum. This chapter interrogates why right-wing libertarians, left-wing anti-corporate activists, nationalists, and spiritual progressives could march under a common anti-vaccine banner. Survey data from Poland, Germany, and the United Kingdom suggest that different ideological motivations can lead to vaccine hesitancy—for example, opposition to equality on one end and distrust of authority on the other—helping to explain how activists from both the far left and far right found common ground in anti-vaccine movements. A conspiracy mentality—which underlies belief in anti-vaccine conspiracy theories—also appears to follow a curvilinear pattern, with its intensity peaking among both left- and right-wing extremists, helping to explain the emergence of ideologically diverse protest coalitions during the pandemic. These findings indicate that left–right self-placement alone is insufficient to segment vaccine audiences. We suggest that other variables may offer a better explanation for vaccine hesitancy. Across the political spectrum, feelings of lost personal control can influence vaccine attitudes in divergent ways—sometimes motivating support for protective measures like vaccination, and at other times leading to withdrawal, skepticism, or delayed action. Effective campaigns should pair authoritative mandates for high-RWA groups with autonomy-affirming, empathetic communication for low-control and left-leaning segments, while systematically debunking misinformation to curb conspiracy-driven resistance.