Timing of national lockdown and mortality in COVID-19: The Italian experience

To evaluate if the pandemic mitigation effects 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).

We collected data published day by daily from the first COVID-19 case until May 3, 2020, the 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 and 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.

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 two 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.

Every new infected subject before lockdown counted on the death toll of the COVID-19 pandemic in Italy.