A death-based mathematical model of the ongoing COVID-19 pandemic

ASICRD model —Susceptible, Infectious, Critically infectious, Removed and Dead was employed to model COVID-19. While the model is certainly very simple, it captures important early dynamics of diseases such as Covid-19. The model is calibrated for the deaths in the linear phase, which turns out to be a 2x2 linear system. The calibration can be done without any knowledge of the model parameters and allows for a universal fitting over the linear phase.As expected the fitted linear model has the first eigenvalue positive, while the second eigenvalue λ 2 is negative, but otherwise free. It turns out, however, that λ 2 ∈ B ⊂ (−∞,0), where B is a compact interval. For each choice of λ 2 we have a distinct value of0. For this model0(λ2) is monotonic in B. This allows for a bracketing of the possible values of 0. For all choices of the remaining free parameters, the linear dynamics is indistinguishable — though the nonlinear dynamics will be different. Another interesting point is that, once the fitting is done, the non-linear dynamics can be described by a one parameter family of sub-models. This allows for a convenient description of the epidemic evolution scenarios. (This is a joint work by Moacyr Silva, Helio Schechtman and Max O Souza)