🧪 Medical Disease Eradication Simulation

This simulation models what it actually takes to drive a pathogen to zero across a whole population — not a single outbreak curve, but a connected network of 16 regions, each running its own SIR-with-vaccination dynamics and importing cases from its neighbors through travel. Adjust the vaccination campaign's coverage rate, toggle real-world ring vaccination (the strategy that ended smallpox), tune cross-border travel and the pathogen's basic reproduction number, then watch regions fall to zero cases one by one — while a single unreached pocket can reseed the whole network through travel, exactly as it does in real eradication campaigns. A stochastic-extinction rule forces case counts to snap to exactly zero once fewer than one real person would be infected, so eradication is modeled as the discrete, hard-won event it really is rather than an asymptotic curve that never quite reaches zero.