  Recommendations around epidemics tend to focus on individual behaviors, with
much less efforts attempting to guide event cancellations and other collective
behaviors since most models lack the higher-order structure necessary to
describe large gatherings. Through a higher-order description of contagions on
networks, we model the impact of a blanket cancellation of events larger than a
critical size and find that epidemics can suddenly collapse when interventions
operate over groups of individuals rather than at the level of individuals. We
relate this phenomenon to the onset of mesoscopic localization, where
contagions concentrate around dominant groups.
