Pandemic as Population Displacement Cascade: COVID-19 Through the Displacement Framework

We apply the displacement framework to pandemic dynamics, interpreting a pandemic as a population-level displacement cascade. The pre-pandemic population ground state S^0_ population is the epidemic equilibrium: a stable ratio of immune to susceptible individuals with a pathogen circulating at endemic levels. A novel pathogen with no pre-existing population immunity introduces maximum displacement D(_ immune), which propagates through social contact networks at a rate determined by the basic reproduction number R_0.

Herd immunity—natural or vaccine-induced—is the return path to S^0_ population. Variants arise through pathogen displacement away from immune recognition. Long COVID is a wrong attractor: a persistent post-infectious physiological state in which D(_ physiology) does not resolve after viral clearance. We state the central proposition: pandemic severity is proportional to D(_ immune) R_0 N, where N is population size.

The framework unifies epidemic dynamics, immune biology, evolutionary virology, and public-health intervention within a single geometric structure.