On the problem of comparing Covid-19 fatality rates

Understanding Covid-19 lethality and its variation from country to country is essential for supporting governments in the choice of appropriate strategies. Adopting correct indicators to monitor the lethality of the infection in the course of the outbreak is a crucial issue. This works highlights how far the time-dependent case fatality rate is a misleading indicator for estimating the fatality in the course of the outbreak, even if our attention is only restricted to the subset of confirmed cases. Our analysis proves that the final case fatality ratio for several major European countries is bound to largely exceed 10%. The largely discussed difference in the fatality ratio between Italy and other major European countries, is to be mostly attributed (except for the case of Germany) to the more advanced stage of the Italian epidemic.