Chaos theory applied to the outbreak of Covid-19: an ancillary approach to decision-making in pandemic context

Sylvain Mangiarotti; Marisa Peyre; Yan Zhang; Mireille Huc; Francois Roger; Yann Kerr

The numerical integration of the model shows that, after a relatively short transient of 10 approximately 15 days, the model trajectory can reach a steady regime laying on a chaotic attractor. Three projections of the phase space are shown in Figure one illustrating that, after convergence, the trajectory will stay in the ranges [+2100; +8000] for the daily number of newly confirmed cases, [-100; +1200] for daily variations of severe cases number and [+30; +100] for daily deaths. Three simulations have been performed from different initial conditions. These 15 small differences generate different trajectories that will all converge to the same chaotic attractor, simultaneously illustrating, the high sensitivity to the initial conditions and the consistency of the dynamical behaviour. A more detailed analysis of the model (see Suppl. Mat. Fig. S2 ) proved that the present dynamic is very close to a phase non-coherent regime, that is, a much less predictable behaviour. The trajectory reconstructed from the observational data 20 (thick black line) shows the relatively good consistency of the model with the observed data (which may undergo various perturbations, which are smoothed by the model). Note that only All rights reserved. No reuse allowed without permission.