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.  Exclusion Criteria:  COVID-like symptoms in the previous 6 months ; Vaccination against SARS-CoV-2 in the previous 12 months;  Risk for the complicated course of COVID-19 due to:  3.1. Hypertension; 3.2. Diabetes mellitus; 3.3. Immunosuppressive conditions; 3.4. Chronic pathology of the respiratory system ; 3.5. Chronic pathology of the cardiovascular system ; 3.6. Malignant tumor ; 3.7. Systemic inflammatory connective tissue disease ; 3.8. Cerebrovascular disease ; 3.9. Chronic hepatitis. Hepatic cirrhosis; 3.10. Inflammatory bowel diseases ; 3.11. Chronic kidney disease ;  Drug or alcohol abuse as suspected by investigator; History of persistent diarrhea of any cause; Use of pre- or probiotics during the last 2 weeks before inclusion or current use; Allergy to any components of the TDS; Technical difficulties to perform virtual study visits. Inability to perform a blood test for antibodies after 6 months Inability to swallow capsules, or choking / coughing while eating