A SIDARTHE Model of COVID-19 Epidemic in Italy

TLDR

COVID‑19, first identified in Wuhan in December 2019, has spread worldwide, with Italy becoming the most affected European country, making accurate epidemic trend prediction essential for planning control measures and anticipating severe cases that strain healthcare capacity. The study introduces a SIDARTHE epidemic model that differentiates infected individuals by diagnosis status and symptom severity. The model incorporates diagnosed versus non‑diagnosed compartments, simulates transmission dynamics, and compares outputs with Italian case data to evaluate countermeasure scenarios. Simulation results demonstrate that redefining the basic reproduction number within this framework captures containment potential, validates the model against real Italian data, and enables comparison of different intervention scenarios.

Abstract

In late December 2019, a novel strand of Coronavirus (SARS-CoV-2) causing a severe, potentially fatal respiratory syndrome (COVID-19) was identified in Wuhan, Hubei Province, China and is causing outbreaks in multiple world countries, soon becoming a pandemic. Italy has now become the most hit country outside of Asia: on March 16, 2020, the Italian Civil Protection documented a total of 27980 confirmed cases and 2158 deaths of people tested positive for SARS-CoV-2. In the context of an emerging infectious disease outbreak, it is of paramount importance to predict the trend of the epidemic in order to plan an effective control strategy and to determine its impact. This paper proposes a new epidemic model that discriminates between infected individuals depending on whether they have been diagnosed and on the severity of their symptoms. The distinction between diagnosed and non-diagnosed is important because non-diagnosed individuals are more likely to spread the infection than diagnosed ones, since the latter are typically isolated, and can explain misperceptions of the case fatality rate and of the seriousness of the epidemic phenomenon. Being able to predict the amount of patients that will develop life-threatening symptoms is important since the disease frequently requires hospitalisation (and even Intensive Care Unit admission) and challenges the healthcare system capacity. We show how the basic reproduction number can be redefined in the new framework, thus capturing the potential for epidemic containment. Simulation results are compared with real data on the COVID-19 epidemic in Italy, to show the validity of the model and compare different possible predicted scenarios depending on the adopted countermeasures.