Consecutive adult (>18 years old) subjects who tested positive for SARS-CoV-2 with nasopharyngeal swab at the local COVID-19 Prevention Centre were included.

Patients were divided into two groups: cases (who performed nasal lavages) and controls (who did not perform lavages), with similar confounding factors (age, comorbidities, vaccination status).

At the moment of diagnosis, patients were asked to fill out an ad hoc questionnaire to evaluate their symptoms at the moment of diagnosis and of negativization.

Subjects were asked to perform, at a daily time of their choice, a nasal swab provided at the moment of enrolment. When the subjects tested negative for the first time, they had to complete the questionnaire once again.

The study was divided into two phases. In the first phase cases were recruited and were given nasal washes (Tonimer Panthexyl®) to be performed three times a day, and in any case after nasal swab. In the second phase controls were recruited and were asked to perform only daily nasal swabs.

Symptoms course and time of negativization were analyzed. Statistic comparisons were made using Kaplan-Meier test. P values <0,05 were considered to be statistically significant.

Inclusion Criteria:

• age >18 years
• starting participation to the study within the first 48 hours since diagnosis
• ability in self-swabbing
• ability in self-administration of nasal lavages

Exclusion Criteria:

• age <18 years
• refusal of participation
• starting participation to the study after the first 48 hours since diagnosis
• no ability in self-swabbing
• no ability in self-administration of nasal lavages