Government restriction efficiency on curbing COVID-19 pandemic transmission in Western Europe

In this article we assess the effectiveness of the restrictions, implemented at government level, to curb the first wave of the COVID-19 outbreak (January-May 2020) in seven European countries. The analysis put in evidence a strong correlation (correlation coefficient greater than 0.85) between one of the statistical parameters of the distribution representing the temporal evolution of the weekly number of patients admitted into the Intensive Cure Unit (ICU), i.e., the skewness, and the Stringency Index, an aggregate synthetic variable that reflects the level of implemented restrictions by a specific country on a scale between 0 (no restrictions) and 100 (full lockdown). Then, to assess if the skewness is consistent in effectively reflecting the applied restrictions, we computed the skewness for non-Covid flu outbreaks during four years from 2014-2015 to 2018-2019 and Covid-19 outbreak, where no restrictions were applied in Italy. The results highlight a significant difference between the values of the skewness for the normal flu with respect to the COVID-19 outbreak. This large difference put in evidence that the implemented restrictions modify the skewness of the ICU hospitalized patient number distribution. The skewness then can be used as a valid indicator to assess if the restriction had any effect on pandemic transmission and can be used as a support for decision makers.