Background: COVID-19 is an asymptomatic condition in 40% of cases, and most symptomatic patients present with mild/moderate disease not requiring hospitalization or intensive care, especially during the Omicron wave, when the hospitalization rate was estimated to be 0.3%. The main port of entry for SARS-CoV-2 in the human body is the nasal cavity and the upper respiratory tract is affected since the early stages of the infection. Nasal irrigation or aerosol by isotonic or hypertonic saline solution is a traditional therapeutic approach for respiratory or nasal inflammation, also featured by prophylactic properties against upper respiratory infections. Methods: We conducted a prospective open-label controlled study to assess the superiority of an already existing medication (Tonimer Lab Panthexyl 800)-a sterile hypertonic solution containing seawater, xylitol, panthenol and lactic acid-to reduce the viral shedding time in patients affected by asymptomatic or mild COVID-19. COVID-19 patients (N = 108) were split into two groups: a treatment arm (50 participants receiving standard of care plus nasal spray 3 times/day with Tonimer Lab Panthexyl 800) and a control arm (58 participants receiving standard of care but nasal spray with Tonimer Lab Panthexyl 800). The two groups, both testing initially positive for SARS-CoV-2 at real-time PCR (RT-PCR) on nasal swab, were followed up over time to assess the daily number of positive swab tests turning negative (study endpoint). Treatment effectiveness at various time lags since the first positive RT-PCR swab test was measured by rate of events in the experimental arm (EER) and in the control arm (CER), absolute risk increase (ARI) = (EER - CER), and number needed to treat (NNT) = (1/ARI). To investigate the endpoint, we used logistic and Cox regression models, expressing the result as odds ratio (OR) and hazard ratio (HR) with 95% confidence interval (95%CI), respectively. The symptoms recorded with a modified COVID-Q questionnaire at both diagnosis and first negative antigenic swab test were compared in each group (treated versus controls) by exact symmetry test. Results: During the first five days of treatment, COVID-19 patients treated with Tonimer Lab Panthexyl 800 were more likely to become negative two days before controls. According to NNT, four subjects had to be treated for five days to achieve the study endpoint in one individual. The negativization rate in patients treated with Tonimer Lab Panthexyl 800 was significantly higher than patients' treated with standard of care alone (OR = 7.39, 95%CI: 1.83-29.8; HR = 6.12, 95%CI: 1.76-21.32). There was no evidence of side effects. Conclusions: Nasal spray with Tonimer Lab Panthexyl 800 was effective against SARS-CoV-2, stopping viral shedding in the treatment arm two days before the control group. This treatment should be continued for at least five days after the first positive swab test for SARS-CoV-2.
Keywords: COVID-19; SARS-CoV-2; early negativization; hypertonic saline solution; nasal irrigation; swab test; viral shedding time.