Elementary time-delay dynamics of COVID-19 disease

Jose Menendez

where is the "natural" transmission rate, a government-action strength parameter, D an additional category that measures the public's reaction to the disease, and N the total population. However, the quality of the available data may not allow for a clean separation of government and public reactions. Furthermore, when the expression in Eq. (3) was applied to the Wuhan data, the fit parameter turned out to be very large, ( > 1000), suggesting poor transferability from country to country. An additional difficulty with Eq. (3) is that the fit parameters will depend on the reporting ratio in a non-trivial way. Accordingly, the simpler expression (4) is used here. The parameter Cmax corresponds to the maximum number of cases, and reflects the combined effort of government and society at large. A significant advantage of using Eq. (4) is that becomes independent of underreporting if is scaled according to the underreporting factor. Therefore, one can ignore underreporting when it comes to modeling the data. The delay differential equation for in Eq (2) ble data or approximated as .