Objective: To evaluate if the pandemic mitigation effect of lockdown in Italy have been influenced by the level of penetration of COVID-19 in Italian Regions at the onset of containment (March 9, 2020).
Methods: We collected data published day by day from the first COVID-19 case until May 3, 2020, date of end of lockdown, by Italy’s Protezione Civile Department. Linear regression analyses were performed to evaluate possible correlations between the number of confirmed cases/100.000 residents as well as the number of new cases/100.000/day before lockdown with the number of deaths/100.000 residents at sixty days, in each Italian region.
Results: We found a significant positive correlation between the number of confirmed cases before lockdown and mortality up to sixty days (p < 0.001; R2 = 0.57) as well as between the incidence rate of new cases per day and mortality up to sixty days (p < 0.001; R2 = 0.73). Regression coefficients indicated about 2 deaths up to sixty days for every new patient with confirmed COVID-19 before lockdown, and 37 deaths for every new infected subject per day until the lockdown decree of March 9, 2020.
Conclusions: Every new infected subject before lockdown counted on the death toll of COVID-19 pandemic in Italy.