Epidemiological trends of COVID-19 epidemic in Italy during March 2020. From 1,000 to 100,000 cases

The COVID-19 epidemic started in Italy by the end of January 2020 and, after one month, it affected 1,049 persons. Based on the Italian Ministry of Health data, we reconstructed the daily course of virus-positive cases and deaths during March 2020 for whole Italy, 19 regions and 2 provinces. From February 29 to March 31 there was a 100.9-fold increase in the cumulative number of cases and a 428.6-fold increase in the number of deaths in Italy. When plotted on a semilogarithmic scale, the curves tended to diverge from linearity with 23%, 16%, and 7% average daily increases during the 3 decades of March. Similarly, the number of deaths decreased from an average daily growth of 19% during the 2nd decade to 10% during the 3rd decade. The correlation coefficients relating the days to cases or deaths during each one of the 3 decades approached the unity. As inferred from the equations of the regression lines relative to the 3 decades, the doubling times of cases were 3.4, 5.1 and 9.6 days, respectively. The doubling times of deaths during the 2nd and 3rd decades were 4.9 and 7.0 days, respectively. There was a broad geographic variability, with a striking gradient from North, where 40.8% of cases and 57.9% of deaths occurred in Lombardy, to South. On the whole, during March there was a trend to epidemic growth decline, but the time for the end of the epidemic will depend on a variety of factors and, at present, it is unpredictable