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

China suffered from the epidemic outbreak earlier than the rest of the world and imposed immediate and stringent confinement measures as a reaction. The positive effects of the Chinese measures have become evident in the past few weeks, and the Chinese data can thus be used as a reference to better analyze the situation in other countries. A variety of approaches may be used. One example consists in collecting data on various cities in a given country and comparing them to a set of historical data collected in a series of cities judged relevant in China. Coupled with epidemic spreading modeling, this procedure may help extrapolate the trends to be expected in the cities under study, and to deduce forecasts for the entire country. Unfortunately, as the European cities under consideration are still in a very early stage of the epidemic's development, this approach is very imprecise and the extrapolations obtained may be of weak reliability. For instance, one such study released on March 8, 2020 predicted that the final total number of diagnosed confirmed cases in Italy after the end of the epidemic would reach approximately 7,000 +/-1,000 [1] . Today we know that this number was significantly underestimated, as four days later the official records exceeded 15,000 confirmed cases. This shows the need of a simpler but more robust method in order to guide authorities.