The new coronavirus SARS-CoV-2 rapidly spread worldwide and the respiratory syndrome it causes, COVID-19, was recognised by WHO as a pandemic: a global threat. For weeks COVID-19 has been on the news and the countermeasures aimed at containing the contagion changed our daily routine. Is it worth staying at home?
Definitely yes.
A novel mathematical model, developed to describe and predict the evolution of this epidemic, tells us that, without any restrictive measure, 70%-80% of the Italian population would have been infected in less than a year: many would have shown symptoms and 10% of the population, namely 6 million people, may have needed intensive care, many in the same time-span. A situation that no healthcare system could have managed. Instead, with very restrictive countermeasures applied in the whole country soon after discovering the first Italian cases, the epidemic could have been over in a short time and only 0.08% of the population, 48 000 people, would have been infected.
These are some results of a study performed in collaboration between Giulia Giordano (DII, University of Trento), Franco Blanchini (University of Udine), Patrizio Colaneri (Politecnico di Milano) and the doctors of the COVID-19 Task Force at the Hospital San Matteo in Pavia: Raffaele Bruno, Alessandro Di Filippo, Angela Di Matteo and Marta Colaneri.
The model parameters were estimated based on the epidemic data from February 20 to March 12; then, several future scenarios were proposed depending on the different – mild, strong, very strong – effect of the adopted social distancing countermeasures.
We now see the results of the milder countermeasures adopted in the beginning: data up to March 20 are perfectly aligned with the epidemic progression in the scenario where the measures have a mild effect. However, the growth of the number of infected people recently slowed down, which allows us to hope that the effect of the more rigid quarantine measures adopted later will be visible soon, in the next weeks.
The contagion peak also moves depending on the adopted measures: if they had a mild effect, the peak would be reached within a couple of months, while, if the effect turned out to be strong, within a couple of weeks.
The simulations and comparison of different scenarios show very clearly that adopting, and rigorously respecting, suitable restrictive measures can have very significant effects on the evolution of the epidemics, reducing the number of infected people, the number of needed intensive care beds, and the number of deaths; the reduction is higher if the measures are stronger. Strong measures can also anticipate the peak (besides reducing its amplitude), thus limiting the duration of the epidemic, while milder measures can delay the peak, thus giving more time to the healthcare system to get ready, but also prolonging the duration of the emergency.
The full paper is available at the following link:
https://arxiv.org/abs/2003.09861
On the Italian press: