Tracking the Covid-19 pandemic : Simple visualization of the epidemic states and trajectories of select European countries & assessing the effects of delays in official response.

Antoine Kevorkian; Thierry Grenet; Hubert Gallee

The evolution of the characteristic time for doubling the daily confirmed cases is often used to measure the speed of epidemic progression. If the epidemic dynamics law was exponential one would expect the doubling time to be constant in time. In the countries considered here the epidemic progression is not exponential but of power law type, which implies an in-built gradual increase of the doubling time. Therefore this increase does not prove by itself that sanitary measures are being effective. Such a conclusion can only be reached when a change of dynamical regime occurs, showing a persistent deviation from the trend such as shown in Fig.1 or from the law given by eq. (1) for Italy and eq. (3) of appendix 1 for other countries (with appropriately determined values of α).