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Table 1 Summary of proposed age-related mechanisms

From: Explaining age disparities in tuberculosis burden in Taiwan: a modelling study

MechanismsDescriptionsNotationPrior distributionParameters
Definition (unit)
m0Base modelNo additional age-related mechanisms are incorporated.βbase0.001–30Infection rate (per year)
m1Immune senescenceThe risk of developing TB disease following recent or remote infection increases with age, potentially related to comorbidities and health-related behaviours.σ(C)0.1–1Multiplier to baseline progression rates for children, compared to adults
σ(E)1–10Multiplier to baseline progression rates for elders, compared to adults
m2Declining transmissionaFrequent Mtb transmission in the past generated a substantial number of latently infected population, who become the elderly cases in the present day. A rapid decline of Mtb transmission happens recently because of improved living standard and health service.βini0.001–30Infection rate prior to t0 (per year)
βend0.001–30Infection rate at 2017 (per year)
t01957–2005Beginning year of transmission decline
m3Age-specific assortativityMixing between age groups lead to different infection tendencies, as a result of social activity and infectiousness. Elders are additionally restricted to mix with younger age groups in order to retain the high burden in the population.w(A)0.2–5Connectivity weight of adults for mixing with others, compared to children
w(E)0.2–5Connectivity weight of elders for mixing with others, compared to children
ε0.01–1Isolation factor for mixing between elders and younger age groups
  1. aWe assumed uniform distributions for all prior parameters with the boundaries described. In models with the mechanism of age-specific assortativity (m3, m23, m13, and m123), βbase, βini, and βend represent the infection rates within children, so those prior distributions were modified as 0.001–10