This article analyzes the visual operations of contagions and their material aftereffects. Data visualizations and diagrams have played a key role in the visual culture of the contagion, and this article explores especially two recurring themes: curves and simulations. The article addresses the data diagrams that describe and predict, advise and control actions during the pandemic. The authors argue that these curves and simulations are also crucial epistemic and aesthetic occurrences that produce the long tale of the epidemic as it pertains to a variety of actions from policy making to affective responses. Furthermore, the text investigates the theme of the operational loop to help us grasp statistical curves and simulations as part of a multiscalar logic of the epidemic image and to discuss the temporal modalities of these various images and diagrams. The article also includes David Benqué’s speculative diagrams of contagion loops that present an artistic response to the theoretical theme.