(a) prevention arm: inclusion criteria: 1. 18 years of age or older and 2. any subject that is circulating and exposed to the public

(a) prevention arm: inclusion criteria: 1. 18 years of age or older and 2. any subject that is circulating and exposed to the public

(a) prevention arm: inclusion criteria: 18 years of age or older and any subject that is circulating and exposed to the public

(a) prevention arm: inclusion criteria: 18 years of age or older and any subject that is circulating and exposed to the public

(a) prevention arm: inclusion criteria: 1. 18 years of age or older and 2. any subject that is circulating and exposed to the public

(a) prevention arm: inclusion criteria: 1. 18 years of age or older and 2. any subject that is circulating and exposed to the public

inclusion criteria: 18 years of age or older and 1. doctors, nurses, ancillary staff , cleaning staff working in intensive care units or emergency departments that care for covid-19 patients, or 2. people performing aerosol-generating procedures on covid-19 patients (i.e. anesthesiologist, nurses, dentists, trans-esophageal sonography technicians, etc.) or 3. relatives of covid-19 index cases who have been in contact (according to the national ministry of health definition in force at the time of the evaluation) or 4. laboratory staff currently running covid-19 tests study authorities will evaluate subjects who fill the pre-screening form and will approve enrollment into the study upon confirming their risk criteria.

inclusion criteria: 18 years of age or older and 1. doctors, nurses, ancillary staff , cleaning staff working in intensive care units or emergency departments that care for covid-19 patients, or 2. people performing aerosol-generating procedures on covid-19 patients (i.e. anesthesiologist, nurses, dentists, trans-esophageal sonography technicians, etc.) or 3. relatives of covid-19 index cases who have been in contact (according to the national ministry of health definition in force at the time of the evaluation) or 4. laboratory staff currently running covid-19 tests study authorities will evaluate subjects who fill the pre-screening form and will approve enrollment into the study upon confirming their risk criteria.