Visual explainer · no golden hash

Outbreak, counterfactually

Drag R₀ and an intervention's strength and watch a settlement's outbreak curve live-solve underneath. The same three-compartment model (Kermack–McKendrick, 1927) that flattened real curves flattens this one — or doesn't, if R_eff never drops below 1.

Live SIR solver
fraction infected days →
2.5
Drives β=R₀·γ. Herd-immunity threshold 1−1/R₀ marked as a teal tick on the R₀ track below.
0.00
Distancing / masking / closures — cuts transmission to R_eff = R₀·(1−c). Set c so R_eff<1 to flip the threshold badge.
5.0
Time before recovery/removal. Anchor range ≈3–10 days across respiratory diseases.
R_eff = 2.50 — grows
threshold flips at R_eff = 1
60%
herd-immunity threshold
1 − 1/R₀
0%
Δ cumulative cases
vs no-intervention baseline
≈ 0 (0–0)
Δ deaths vs baseline
IFR band applied
Adjustable assumptions
Accounting panel — every knob that moves the death estimate
1.0%
Deaths = IFR × cumulative infections. Band shown is midpoint ±50% — IFR is one of the most contested numbers in any real outbreak's accounting; this page ships a range, not a point.
—
Held fixed at the New Tripoli post-Wake population for scale — swap R₀/c/γ above, not this.
Documented record
Documented record
Kermack, W.O. & McKendrick, A.G. (1927), "A Contribution to the Mathematical Theory of Epidemics," Proc. R. Soc. A 115(772) — the SIR model this page solves live.
Delamater, P.L. et al. (2019), "Complexity of the Basic Reproduction Number (R₀)," Emerging Infectious Diseases 25(1) — R₀ estimation caveats.
Heffernan, J.M., Smith, R.J. & Wahl, L.M. (2005), "Perspectives on the basic reproductive ratio," J. R. Soc. Interface 2(4).
Caveats
R₀ and IFR are both estimation ranges, not fixed constants — real outbreaks revise both mid-event. This solver holds γ constant across the outbreak (no reinfection, no waning immunity, no age structure) — a simplification, not a forecast.
Genre & further reading (published epidemiology, not alt-history genre — this page has no local-language counterfactual corpus to cite)
Standard SIR pedagogy; see also Anderson & May, Infectious Diseases of Humans (1991) for compartmental-model extensions.

This is an explorable explainer, not a frozen result — it computes over the R₀/c/γ/IFR you set above, and ships no canonical hash. When the underlying outbreak-response canon locks, nt_outbreak_counterfactual can be promoted to a deterministic MCP chain (parameters → hashed identity), the way ch_stadium_capacity already is.

SOURCE // Kermack & McKendrick (1927), Proc. R. Soc. A · Delamater et al. (2019), Emerging Infectious Diseases. Figures are ✦ speculative estimates over a standard compartmental model; population scale ◆ canon §5. No network calls at runtime (fonts excepted). · Sitemap