Tracing DAY-ZERO and Forecasting the Fade out of the COVID-19 Outbreak in Lombardy, Italy: A Compartmental Modelling and Numerical Optimization Approach.

Lucia Russo; Cleo Anastassopoulou; Athanassios Tsakris; Gennaro Nicola Bifulco; Emilio Fortunato Campana; Gerardo Toraldo; Constantinos Siettos

In particular, in many studies that use SEIRD models, the parameter σ is set equal to the inverse of the mean incubation period (time from exposure to the development of symptoms) of a virus. However, the incubation period does not generally coincide with the time from exposure to the time that someone starts 140 to be infectious. Regarding COVID-19, it has been suggested that an exposed person can be infectious well before the development of symptoms [16] . With respect to the incubation period for SARS-CoV-2, a study in China [17] suggests that it may range from 2-14 days, with a median of 5.2 days. Another study in China, using data from 1,099 patients with laboratory-confirmed 2019-nCoV 145 ARD from 552 hospitals in 31 provinces/provincial municipalities suggested 8 . CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.