Open Access
Table 3
Parameters used for the numerical simulation of the SEIHRD model with optimal control.
| Symbol | Description | Value | Unit | Reference / Justification |
|---|---|---|---|---|
| Λ | Population inflow rate (births/immigration) | 100 | individuals/day | Assumed demographic stability |
| β₀ | Basic transmission rate of the XEC variant | 0.52 | 1/day | Estimated from average R₀ between 2 and 3 |
| θ | Combined rate of vaccination and treatment | Variable (u₁ + u₂) | – | Optimal control |
| θᵥ(t) | Effective vaccination rate (ELIXIR COVID) | u₁(t) | 1/day | Control variable |
| u₂(t) | Rate of ADSAK COVID treatment | u₂(t) | 1/day | Control variable |
| µ | Natural mortality rate | 1/3650 | 1/day | Assuming life expectancy of 10 years |
| α₁ | Relative infectivity of symptomatic infected individuals | 0.9 | – | More contagious than hospitalized cases |
| α₂ | Relative infectivity of unburied deceased individuals | 0.5 | – | Moderate post-mortem infectivity |
| δ | Transmission factor of hospitalized individuals | 0.3 | – | Limited public contact |
| σ₁ | Effectiveness of hospital isolation | 0.85 | – | High isolation level |
| σ₂ | Rate of safe burial of deceased | 0.7 | – | Partially controlled funeral practices |
| p | Proportion progressing from exposure to latent infection | 0.4 | – | Estimated clinical data |
| α | Progression rate to infectious state | 0.2 | 1/day | Average incubation period: 5 days |
| ηE | Hospitalization rate of exposed individuals | 0.01 | 1/day | Low for asymptomatic cases |
| ηI | Hospitalization rate of symptomatic infected individuals | 0.1 | 1/day | Hospital burden data |
| ϕ₁ | Exit rate from exposed class (recovery or worsening) | 0.2 | 1/day | Average value |
| ϕ₂ | Exit rate from symptomatic infected class | 0.25 | 1/day | Average infection duration: 4 days |
| ϕ₃ | Exit rate from hospitalized class (recovery or death) | 0.1 | 1/day | Average hospitalization: 10 days |
| γE | Recovery rate of exposed individuals | 0.05 | 1/day | Spontaneous recovery |
| γH | Recovery rate of hospitalized individuals | 0.06 | 1/day | Dependent on care quality |
| δE | Mortality rate among exposed individuals | 0.005 | 1/day | Estimated |
| δI | Mortality rate among symptomatic infected individuals | 0.01 | 1/day | Estimated |
| q | Burial rate of deceased individuals | 0.2 | 1/day | Average post-declaration |
| B₁ | Weight of treatment/vaccination cost in objective function | 0.5 | – | Balanced efficiency vs. cost |
| C₁ | Weight of health cost for deceased individuals | 10 | – | High socio-economic impact |
| C₂ | Weight of cost for symptomatic infected individuals | 7 | – | Significant health impact |
| T | Duration of the optimal control strategy | 180 | days | 6-month campaign |
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