The R-number isn't a number — it's an emergent property of a feedback system. Herd immunity isn't a threshold — it's a tipping point. The Epidemiology scenario pack makes these dynamics playable, not just describable.
Requires Emergent Pro ($9/mo). Also includes Forest Ecosystem and Bullwhip Effect.
The standard susceptible–infected–recovered model is taught in every epidemiology course. What's almost never taught is the feedback structure underneath: why vaccination rates exhibit tipping-point behavior, why intervention timing matters more than intervention intensity, and why well-intentioned responses can extend an outbreak.
A full susceptible–infected–recovered compartment model with tunable transmission rate (β), recovery rate (γ), and R₀. Watch exponential growth emerge from a single infected seed — then learn where the levers are.
Vaccination coverage doesn't reduce risk linearly — it hits a tipping point. Below threshold, outbreaks are possible. Above threshold, the pathogen can't sustain transmission. Play the non-linearity directly.
The same intervention applied at week 2 vs week 6 produces radically different outcomes. Experience the lag between policy and effect — and why acting early looks unnecessary until you see the counterfactual.
As case counts rise, behavior changes. As behavior changes, case counts fall. As cases fall, precautions relax. The resulting oscillation is a second-order loop that drives recurrent waves — and resists simple top-down control.
Manage a live SIR outbreak — tune vaccination speed, contact reduction, and awareness campaigns. Keep hospitals below capacity and achieve herd immunity before week 20.