inclusion criteria: age ≥ 18 - ≤ 65 years; male or non-pregnant female; informed virtual pre-consent and paper signed consent forms; confirmed symptomatic covid-19 lasting 0-5 days; subject understands and agrees to comply with study procedures including triple blood analysis for anti-sars-cov-2 igg;

inclusion criteria: age ≥ 18 - ≤ 65 years; male or non-pregnant female; informed virtual pre-consent and paper signed consent forms; confirmed symptomatic covid-19 lasting 0-5 days; subject understands and agrees to comply with study procedures including triple blood analysis for anti-sars-cov-2 igg;

inclusion criteria: age ≥ 18 - ≤ 65 years; male or non-pregnant female; informed virtual pre-consent and paper signed consent forms; absence of covid-19 symptoms at time of screening; symptomatic household with confirmed covid-19 infection; sharing the same premise/flat with a covid-19 patient at least 8 hours per day; unprotected (without mask) close contact lasting more than 4 hours with a coughing person who has been further confirmed covid-19 the duration of contact with the first patient with covid-19 is less than 14 days subject understands and agrees to comply with study procedures including triple blood analysis for anti-sars-cov-2 igg in the case of the disease; subject has a smartphone and can make photocopies of documents using a smartphone and send them via messengers.

inclusion criteria: age ≥ 18 - ≤ 65 years; male or non-pregnant female; informed virtual pre-consent and paper signed consent forms; absence of covid-19 symptoms at time of screening; symptomatic household with confirmed covid-19 infection; sharing the same premise/flat with a covid-19 patient at least 8 hours per day; unprotected (without mask) close contact lasting more than 4 hours with a coughing person who has been further confirmed covid-19 the duration of contact with the first patient with covid-19 is less than 14 days subject understands and agrees to comply with study procedures including triple blood analysis for anti-sars-cov-2 igg in the case of the disease; subject has a smartphone and can make photocopies of documents using a smartphone and send them via messengers.

inclusion criteria: 1. age ≥ 18 - ≤ 65 years; 2. male or non-pregnant female; 3. informed virtual pre-consent and paper signed consent forms; 4. absence of covid-19 symptoms at time of screening; 5. symptomatic household with confirmed covid-19 infection; 6. sharing the same premise/flat with a covid-19 patient at least 8 hours per day; 7. unprotected (without mask) close contact lasting more than 4 hours with a coughing person who has been further confirmed covid-19 8. the duration of contact with the first patient with covid-19 is less than 14 days 9. subject understands and agrees to comply with study procedures including triple blood analysis for anti-sars-cov-2 igg in the case of the disease; 10. subject has a smartphone and can make photocopies of documents using a smartphone and send them via messengers.

inclusion criteria: 1. age ≥ 18 - ≤ 65 years; 2. male or non-pregnant female; 3. informed virtual pre-consent and paper signed consent forms; 4. absence of covid-19 symptoms at time of screening; 5. symptomatic household with confirmed covid-19 infection; 6. sharing the same premise/flat with a covid-19 patient at least 8 hours per day; 7. unprotected (without mask) close contact lasting more than 4 hours with a coughing person who has been further confirmed covid-19 8. the duration of contact with the first patient with covid-19 is less than 14 days 9. subject understands and agrees to comply with study procedures including triple blood analysis for anti-sars-cov-2 igg in the case of the disease; 10. subject has a smartphone and can make photocopies of documents using a smartphone and send them via messengers.