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SEIR R0 with vital dynamics and vaccine coverage: infeasible coverage boundary · case 05

A campaign that needs exactly 100% coverage is reported as infeasible.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

R0 = beta*sigma/((sigma+mu)*(gamma+mu)); when R0<=1 return [R0,0.0,0.0]; herd threshold 1-1/R0; critical coverage threshold/efficacy, None if it exceeds 1 (exactly 1 is feasible); values rounded to 6; None for invalid rates or efficacy outside (0,1].

Why this case matters

Compartmental epidemic calculations drive outbreak forecasts, vaccine targets and hospital planning; a single wrong flow, rate conversion or boundary silently changes every downstream number.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: exact R0 of two with half efficacy	`[2.0, 0.5, null]`	`[2.0, 0.5, 1.0]`	Failed

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