Double-blind, Randomized, Parallel, Placebo-controlled Clinical Study to Evaluate the Viral Load of SARS-CoV-2 (COVID-19) in the Oral Cavity of SARS-CoV-2 Positive Subjects After the Use of a Mouthwash Containing Cetylpyridinium Chloride 0,07%.

Double-blind, parallel, randomized, placebo-controlled clinical study. Subjects with confirmed SARS-CoV-2 infection by PCR or antigen rapid test, asymptomatic or with mild COVID-19 symptoms will be included. Subjects who agree to participate and who are eligible will be randomized to perform a mouth rinse and gargle with a 0.07% CPC mouthwash (experimental) or with a substance of the same color (placebo). Saliva samples will be collected at baseline (i.e., before wash) and 1 hour and 3 hours after wash. Saliva samples will be transferred to a central laboratory for SARS-CoV-2 viral load determination, nucleocapsid protein levels determination, rapid antigen testing, viral infectivity analysis and storage.

Study procedures will be as follows:

The study procedures will take place in 1 day (total interval of 3 hours from the baseline sample collection to the last sample collection).

The study samples will be saliva samples (1-1.5 ml) collected at baseline and 1 and 3 hours after the intervention. The intervention will be the use of a mouthwash (washes and gargles) for one minute with 15 ml of either CPC Protect® (CPC group) or colored distilled water (control group).

Candidates with a positive result of PCR or antigen rapid test for SARS-CoV-2 will be identified by study nurses, certified nursing assistants, and dentists at primary health care centers of the Metro Nord health administrative region of Catalonia. The investigator will obtain the candidates' informed consent and will verify that the subject meets all the inclusion criteria and none of the exclusion criteria. The researcher will assign a correlative kit number (randomization) and instruct the subject in the procedure of self-collection of a saliva sample.

Baseline: The subject will self-collect the baseline saliva sample in front of the investigator, who will be able to correct the errors observed in the procedure.

Hour 0: After the obtention of the baseline saliva sample, the subject will rinse and gargle with 15 mL of mouthwash (experimental or placebo) for 1 minute (30 seconds of rinsing and 30 seconds of gargling).

The researcher will indicate to the subject the hours in which the second and third saliva samples should be taken. The subject must avoid brushing their teeth, eating and drinking, except water, until the rest of the saliva samples are collected and may return home.

Hour 1: One hour after mouthwash use, the subject will self-collect the second saliva sample (1-hour sample).

Hour 3: Three hours after mouthwash use, the subject will self-collect the third saliva sample (3-hour sample).

The investigator will contact the subject to confirm the correct collection of saliva samples (1 hour and 3 hours) at the indicated times and will record it in the study application.

Saliva samples will be collected at the center and/or at the subjects' residence and will be transferred to the Clinical Laboratory Metropolitana Nord in Hospital Universitari Germans Trias i Pujol (HUGTiP) for the viral load analysis by RT-PCR. The remaining saliva volume will be transferred to IrsiCaixa's Laboratory (located in the HUGTiP) for the ELISA analysis and the rest of the analysis, and for storage in those cases where the subject's IC is available for it.

Eligibility Criteria:
Inclusion Criteria:

1. Age equal to or greater than 18 years
2. 2. Confirmation of SARS-CoV-2 infection, determined by PCR or validated rapid antigen test1 from a nasopharyngeal smear performed in ≤3 days.
3. Without symptoms of COVID-19 or with symptoms with ≤3 days of evolution
4. Cognitive and motor ability to perform mouthwashes and gargles
5. Willingness to comply with the requirements of the protocol
6. Understanding of the information provided in relation to the objectives and procedures
7. Provide your consent freely to participate in the study.

Exclusion Criteria:

1. Use of mouthwashes, in the last 24 hours
2. Use of VITIS pastes and / or PERIO AID gel, in the last 24 hours
3. Four or more days of symptoms compatible with COVID-19.
4. Recent medical diagnosis (≤ 1 month) of pneumonia
5. Cognitive impairment or other reason that, in the investigator's discretion, contraindicates participation in the study
6. Hyposialia