Misinformation spread is the movement of false or misleading claims through a population via sharing. Systems modellers often treat it like an epidemic: people move between susceptible, exposed, sharing and immune states, and a few highly active sharers can dominate transmission.
Example
A claim reaches many people because a small group of very active accounts shares it repeatedly, while most users never share it. Interventions that act on that structure, such as prebunking, differ from those that treat every user alike.