inclusion criteria: male or female, aged >= 18 years sars-cov-2-exposed subjects, as household members and/or contacts of covid-19 patients (group 1). in this group are included health care professionals in contact with covid-19 patients. or covid-19 patients, asymptomatic or paucisymptomatic in home situation who are not in treatment with any anti covid-19 medication (group 2) absence of any covid-19 symptom in last week before randomization (fever >37.5°c, cough, dyspnea) (only for group 1 subjects) paracetamol treatment is accepted only for group 2. participant is willing and able to give informed consent for participation in the study (either recorded during a telephonic interview or signed in person) and agrees with the study and its conduct.

inclusion criteria: male or female, aged >= 18 years sars-cov-2-exposed subjects, as household members and/or contacts of covid-19 patients (group 1). in this group are included health care professionals in contact with covid-19 patients. or covid-19 patients, asymptomatic or paucisymptomatic in home situation who are not in treatment with any anti covid-19 medication (group 2) absence of any covid-19 symptom in last week before randomization (fever >37.5°c, cough, dyspnea) (only for group 1 subjects) paracetamol treatment is accepted only for group 2. participant is willing and able to give informed consent for participation in the study (either recorded during a telephonic interview or signed in person) and agrees with the study and its conduct.

inclusion criteria: 1. male or female, aged >= 18 years 2. sars-cov-2-exposed subjects, as household members and/or contacts of covid-19 patients (group 1). in this group are included health care professionals in contact with covid-19 patients. or 3. covid-19 patients, asymptomatic or paucisymptomatic in home situation who are not in treatment with any anti covid-19 medication (group 2) 4. absence of any covid-19 symptom in last week before randomization (fever >37.5°c, cough, dyspnea) (only for group 1 subjects) 5. paracetamol treatment is accepted only for group 2. 6. participant is willing and able to give informed consent for participation in the study (either recorded during a telephonic interview or signed in person) and agrees with the study and its conduct.

inclusion criteria: 1. male or female, aged >= 18 years 2. sars-cov-2-exposed subjects, as household members and/or contacts of covid-19 patients (group 1). in this group are included health care professionals in contact with covid-19 patients. or 3. covid-19 patients, asymptomatic or paucisymptomatic in home situation who are not in treatment with any anti covid-19 medication (group 2) 4. absence of any covid-19 symptom in last week before randomization (fever >37.5°c, cough, dyspnea) (only for group 1 subjects) 5. paracetamol treatment is accepted only for group 2. 6. participant is willing and able to give informed consent for participation in the study (either recorded during a telephonic interview or signed in person) and agrees with the study and its conduct.