Background. The paper concerns the SARS-CoV2 (COVID-19) pandemic that, starting from the end of February 2020, began spreading along the Italian peninsula, by first attacking small communities in north regions, and then extending to the center and south of Italy, including the two main islands. Objective. The creation of a forecast model that manages to alert the decision-making bodies and, in particular, the healthcare system, to hinder the emergence of any other pandemic outbreaks, or the arrival of subsequent pandemic waves. Methods. A new mathematical model to describe the pandemic is given. The model includes the class of undiagnosed infected people, and has a multi-region extension, to cope with the in-time and in-space heterogeneity of the epidemic. Results. We obtain a robust and reliable tool for the forecast of the total and active cases, which can be also used to simulate different scenarios. Conclusions. We are able to address a number of issues, such as assessing the adoption of the lockdown in Italy, started from 11 March 2020, and how to employ a rapid screening test campaign for containing the epidemic.
The hidden side of COVID-19 spread in Italy