Inclusion Criteria:  Age 18 - 75 years. Written informed consent. Good knowledge of respective language. Willingness to give swab samples. Willingness to give blood and saliva samples.  Exclusion Criteria:  ≥76 years < 18 years. Participation in another clinical study in the past 30 days or planned during study conduct. Permanent intake of antimicrobial, antiviral, immune suppressive substances. Surgical intervention in the 3 months prior enrolment or planned intervention during the study conduct. Known diabetes mellitus. Known atopy (a constitution to produce an exaggerated immune response to otherwise harmless environmental substances, with clinical manifestation of an allergic disease such as allergic rhinitis, eczema, asthma, atopic dermatitis, etc.) Cystic Fibrosis, bronchopulmonary dysfunction, COPD. Known immune system disorders and degenerative disorders (autoimmune disorders, AIDS, leukaemia, lymphoma, myeloma). Known metabolic or resorption disorders. Known liver or kidney illnesses (chronic hepatitis, liver cirrhosis, chronic kidney insufficiency). Serious health conditions (limited general condition, auto-immune diseases, tumorous diseases, neurological disorders) Known allergies to plants of the compositae family (e.g. camomile or dandelion) or one of the compounds in the investigational product Known or planned pregnancy during study period (effective contraception is required).