Theory and Modern Applications
Table 1 Descriptions and initial values of model variables
From: A dynamic optimal control model for COVID-19 and cholera co-infection in Yemen
Variables | Description | Initial conditions | Source |
|---|---|---|---|
N | Total population size | 29,825,964 | [44] |
S | Susceptible to both COVID-19 and cholera | N | Assumed |
E | Number of exposed to COVID-19 | [0,N × 10−6] | [17] |
A | Number of asymptomatic COVID-19 individuals | 0 | Assumed |
\(I_{1}\) | Number of COVID-19- infected individuals | 0 | Assumed |
\(R_{1}\) | Recovered from COVID-19 | 0 | Assumed |
\(P_{1}\) | Perished by COVID-19 | 0 | Assumed |
\(I_{R2}\) | Infected with cholera after recovery from COVID-19 | 0 | Assumed |
\(I_{2}\) | Infected with cholera | \(I_{0} = 750\) person | [10] |
\(R_{2}\) | Recovered from cholera | 0 | Assumed |
\(P_{2}\) | Perished by cholera | 0 | Assumed |
\(I_{1R}\) | Infected with COVID-19 after recovery from cholera | 0 | Assumed |
\(I_{12}\) | Co-infected with both cholera and COVID-19 | 0 | Assumed |
\(R_{12}\) | Recovered from both cholera and COVID-19 | 0 | Assumed |
\(P_{12}\) | Perished by both COVID-19 and cholera | 0 | Assumed |
B | Bacterial concentration in the environment (free bacteria population living in the environment) | 275 × 103 (cell/ml) | [10] |