Fig. 3: SIR model extensions for variable infectiousness, multiple routes of transmission and age-specific transmission.

a, Split of the I group by level of symptoms (none/mild, moderate, severe), with varying contact (k) and infectiousness (π) indicated qualitatively by + (low), ++ (medium) and +++ (high). Infected groups may recover at different rates (γ_k). b, Multiple routes of transmission through individuals in the community (I_C), hospital (I_H) or awaiting funeral (F) with varying transmission rates (β_k). c, Split of each group into age brackets (for example, I₁, I₂, …) to account for age-specific contact patterns and transmission rates (φ_i). Birth occurs only into the S₁ group, death affects each group and aging is represented by flows between adjacent age brackets (for example, from I₁ to I₂) at a rate a.