- patient participation in a covid-19 research study using experimental drugs, - use of an antiseptic mouthwash for 48 h before the start of the study - any known hypersensitivity or allergy to components of the mouthwashes.

- patient participation in a covid-19 research study using experimental drugs, - use of an antiseptic mouthwash for 48 h before the start of the study - any known hypersensitivity or allergy to components of the mouthwashes.