Do health crises lead to a rise in antisemitism, and why? Scholars have recorded a close association between health crises and the prevalence of antisemitic stereotypes and the occurrence of antisemitic violence. We show that a similar relationship holds for the Covid-19 pandemic, and explore the reasons behind this relationship. We argue that pandemics can activate cultural scripts linking the spread of infectious diseases to Judaism, especially among Christian conservatives. We rule out alternative explanations that relate the activation of antisemitic stereotypes to modern forms of antisemitism, in particular right-wing ideology. Our data come from an original survey (n=17,800) fielded in Germany during the COVID-19 pandemic. Our work demonstrates the deep cultural roots of exclusionary political attitudes and the mechanisms behind their activation.