Modeling the COVID-19 outbreaks and the effectiveness of the containment measures adopted across countries

Edward De Brouwer; Daniele Raimondi; Yves Moreau

Italy is the first European country that has been severely hit by the COVID-19 pandemic, and, at the time of writing, it is the second nation in the world in terms of cases, with 92,472. The Italian government reacted to the epidemic by closing all schools and universities on March 4, 2020, putting the north of Italy under lockdown on March 8, 2020, and extending this lockdown to the entire country few days later, on March 10, 2020. On March 20, 2020, the government introduced even stricter measures, banning open-air sports and closing parks and public green. We used the data of the Italian COVID-19 outbreak provided by the Protezione Civile to infer the R 0 before and after the containment measures were implemented. The free parameters are the β i associated to each containment measure introduced and γ that was kept constant across the containment measures. From this analysis, shown in Fig. 2 , it appears that the initially inferred R 0 = 2.68 (CI 95% [2.42, 3 .08]) is in line with the 3.1 estimate provided in (15) . The R 0 = 1.86 (CI 95% [1.36, 2.37]) inferred after the nationwide lockdown in effect from March 10, 2020 suggests that the effectiveness of the containment measures was gradual and did not immediately bring R 0 below 1. Nevertheless, the data clearly departed from a situation without measures put in place (see Suppl.