A study of SARS-CoV-2 evolution in Italy: from early days to secondary effects after social distancing

Marco Claudio Traini; Carla Caponi; Riccardo Ferrari; Giuseppe Vittorio De Socio

In Fig. 2 the behavior of the two parameters as a function of time. The rate of change r e = 0.33 day −1 assumes the same values for the gradually changing quantities. The parametrization (10), in particular, is chosen to simulate the behavior of screening system to select infected (and a-symptomatic) individuals. In Fig. 3 (upper panel) the per-day number of tests performed in Italy in last weeks are explicitly shown. The number increases in time following the adopted measures, an enhancement coherent with the parametrization (10) as already emphasized in the caption of Fig. 2 . On the other hand if one compares the behavior of the number of tests as shown in Fig. 3 (upper panel) with the percentage of positive test (lower panel), one can conclude that the percentage is basically stable (around 22%) while the number of tests increases: a clear signal of the increased rapidity of the screening results.