In vitro inactivation of SARS-CoV-2 with 0.5% povidone iodine nasal spray (Nasodine) at clinically relevant concentrations and timeframes using tissue culture and PCR based assays

BACKGROUNDThere has been considerable speculation regarding the potential of PVP-I nasal disinfection as an adjunct to other countermeasures during the ongoing SARS-CoV-2 pandemic. Nasodine is a commercial formulation of 0.5% PVP-I that has been evaluated for safety and efficacy in human trials as a treatment for the common cold, including a Phase III trial (ANZCTR: ACTRN12619000764134). This study presents the first report of the in vitro efficacy of this formulation against SARS-CoV-2. METHODSWe conducted in vitro experiments to determine if the PVP-I formulation inactivated SARS-CoV-2 using two independent assays and virus isolates, and incorporating both PCR-based detection and cell culture methods to assess residual virus after exposure to the formulation. RESULTSBased on cell culture results, the PVP-I formulation was found to rapidly inactivate SARS-CoV-2 isolates in vitro in short timeframes (15 seconds to 15 minutes) consistent with the minimum and maximum potential residence time in the nose. The Nasodine formula was found to be more effective than 0.5% PVP-I in saline. Importantly, it was found that the formulation inactivated culturable virus but had no effect on PCR-detectable viral RNA. CONCLUSIONSThe PVP-I formulation eliminated the viability of SARS-CoV-2 virus with short exposure times consistent with nasal use. PCR alone may not be adequate for viral quantification in nasal PVP-I studies; future studies should incorporate cell culture to assess viral viability. Nasal disinfection with PVP-I may be a useful intervention for newly-diagnosed COVID-19 patients to reduce transmission risk and disease progression to the lower respiratory tract.