In Cohort 1: incidence of new SARS-CoV-2 cases in the group of LCT recipients versus placebo recipients in family or close friend/contact/cohabitant contacts of index COVID-19 case;In Cohort 2: differences in the number of cases that progress from asymptomatic or milddisease to severe COVID-19 pneumonia of patients using LCT versus the placebo group.

In Cohort 1: incidence of new SARS-CoV-2 cases in the group of LCT recipients versus placebo recipients in family or close friend/contact/cohabitant contacts of index COVID-19 case;In Cohort 2: differences in the number of cases that progress from asymptomatic or milddisease to severe COVID-19 pneumonia of patients using LCT versus the placebo group.