Povidone iodine (PVP-I) gargles inhibited the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and effectively limited its infectivity in saliva for an hour in COVID-19 patients. In this Japanese study published in the Journal of Hospital Infection, researchers enrolled 35 patients, aged ≥20 years, with Covid-like symptoms in the last 7 days or asymptomatic patients with a cycle threshold (Ct) value less than 40 for viral RNA on saliva RT-PCR. Patients with thyroid disease or iodine allergy were excluded from the trial. At the start of the study, the patients collected the saliva samples by spitting into a sterile cup. They were asked to gargle with PVP-I gargle solution (20 ml diluted 15 times with water) for 20 seconds thrice daily and then rinse their mouths with water. Saliva samples were then collected immediately after gargling, after 30 minutes, after one hour later and 2 hours later. Viral RNA and titers were measured at all four time points. The samples were tested to detect and quantify the infectious viral load on RTPCR. Out of the 35 patients recruited, only 11 were included in the final analysis; the rest were not included on account of insufficient viral titer or undetectable viral RNA.

There was a marked decline in viral RNA copies in the samples taken just after gargling, at 30 minutes and 60 minutes after gargling, compared with before gargling. A significant decrease in viral titer (infectious virus particles) was also noted immediately after gargling and one hour after gargling, compared with before gargling. Though the reduction in viral titer after 30 minutes did not reach statistical significance, it was still lower than in the samples collected before gargling. The authors therefore concluded that gargling with the antiseptic PVP-I is an effective tool to reduce the risk of transmission of infection during orodental examination and/or treatment.

Source: Seikai T, et al. J Hosp Infect. 2022 Jan 15;S0195-6701(22)00006-8.