[Epidemiology and public health in the COVID-19 epidemic]

In the last year, all have suffered the devastating consequences of the SARS-CoV-2 epidemic. Over the course of a few months, the news media has bombarded us with messages about incidences, lethality, or even more technical measurements such as R0 or the attack rate. With this update, we hope to clarify basic concepts on the dynamic of the epidemic as well as present what is known about it as of the time of writing. To do so, the information available from international bodies such as the World Health Organization as well as the Ministry of Health has been extracted and used. In no case is it to be understood as a fixed or known situation; it is a situation that, in contrast, is invariably changeable.