Computational Modeling of Interventions and Protective Thresholds to Prevent Disease Transmission in Deploying Populations

Table 4

Model parameters for hepatitis A transmission model.

Parameter	Description	Value	Source
𝑏IN	Inward troop rotation rate	Varies over duration of deployment	[3, 16]
𝑏OUT	Outward troop rotation rate	Varies over duration of deployment	[3, 16]
𝛽𝑖𝑖	Effective transmission rate within unit 𝑖	Function of attack rate
𝛽𝑖𝑗	Effective transmission rate between units 𝑖 and 𝑗	Function of attack and contact rates
𝛽𝑖LOCAL	Effective transmission rate between unit 𝑖 and local population	Function of attack rate, contact rate, and local measles incidence
𝛽𝑖𝑊	Effective transmission rate due to environmental exposure	Function of attack rate, consumption of local food, and proportion of local food that is contaminated
𝑟	Proportion of infections that are asymptomatic	85% (76%–97%)	[44]
𝜃	Proportional reduction in infectivity for asymptomatic individuals	10% (0%–25%)	[44]
𝜒	Hepatitis A attack rate (soldiers) via direct transmission	0.82% (0.82%–1.3%)	[44]
𝜒𝑊	Hepatitis A attack rate (soldiers) via environmental consumption	2.2% (2.2%–3.5%)	[44]
𝑐𝑖	Contact rate with local population for unit 𝑖	Varies by unit
𝐶𝑖𝑗	Contact rate between unit 𝑖 and unit 𝑗	Varies by unit
𝑐𝑖𝑊	Contact rate with environmental reservoir	Varies by unit
incLOCAL	Hepatitis A incidence rate for local population	Varies over duration of deployment	[51–53]
𝜌𝑖	Vaccination rate for unit 𝑖 (90% vaccine efficacy)	Scenario-dependent
1/𝜓	Duration of lag prior to full vaccine-induced immunity	30 days	[44]
𝜇	Background casualty rate for all units	0.0007825 1/day	[16]
𝜇𝐻	Hepatitis A case fatality rate	0.3% (0.1%–0.8%)	[8, 45, 46]
1/𝜀	Duration of hepatitis A incubation period	14 days	[41, 42]
1/𝛾	Duration of hepatitis A infectious period	21 days	[42, 54]
𝑊	Proportion of local food that is contaminated	20% (5%–50%)	Estimated