Heterogeneous Mixing — Core Group Epidemics
Two-group SIR with assortative mixing: high-risk core drives transmission
Population Structure
Core group fraction p_c:
0.10
Core R₀ (within core):
4.0
General pop. R₀:
0.8
Core→General mixing q:
0.30
Recovery rate γ:
0.1
Reset
Pause
Two-group SIR mixing matrix:
β_ij = β·[(1−q)δ_ij + q/N_j]
Effective R₀ = ρ(next-gen matrix)
Core threshold: p_c·R₀_c > 1
Targeted vaccination of core
highly efficient (Yorke 1978)
R₀ effective:
—
Core infected:
—
Gen. infected:
—
Final size:
—