Table 2 Setting initial parameters and variables.

The prior transmission rate in each county is scaled by population density using a baseline transmission rate β0 as inferred through 13 March 2020. The relative transmission rate (μ), latency period (Z), infectious period (D), and mobility factor (θ) are fixed at posterior values inferred through 13 March 2020. Values are shown for the median and 95% CIs in the parentheses. The initial numbers of exposed individuals E and unreported infected individuals Iu are drawn from uniform distributions U(0,18C) and U(0,20C) 9 days before the reporting date (T0) of the first case. Here, C is the total number of reported cases between days T0 and T0 + 4.

Parameter/variableValues
Baseline transmission rate (β0, day−1)0.95 (0.84, 1.06)
Relative transmission rate (μ)0.64 (0.56, 0.70)
Latency period (Z, day)3.59 (3.28, 3.99)
Infectious period (D, day)3.56 (3.21, 3.83)
Mobility factor (θ)0.15 (0.12, 0.17)
Reporting rate (α), prior0.080 (0.069, 0.093)
Initial exposed population (E)U(0,20C)
Initial unreported infected population (Iu)U(0,18C)