Povidone iodine nasal spray, mouthwash can limit coronavirus spread: JAMA

France: Nasopharyngeal application of povidone iodine (PI) in the form of nasal spray, gargle, and mouthwash may reduce viral load in COVID-19 patients, finds a recent study in the journal JAMA Otolaryngology - Head & Neck Surgery.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted from person-to-person primarily through the aerosolization of droplets that contain contaminated nasopharyngeal secretions. With contact time as short as 15 seconds, PI solutions at concentrations as low as 0.5% can rapidly inactivate SARS-CoV-2 in vitro. Jeremy Guenezan, University Hospital of Poitiers, Poitiers, France, and colleagues investigated whether nasopharyngeal PI application could reduce the viral load of patients with nonsevere coronavirus disease 2019 (COVID-19) symptoms.

The study included outpatients (≥18 years old) who tested highly positive for SARS-CoV-2 RNA by reverse transcription-polymerase chain reaction (RT-PCR) in nasopharyngeal swabs within the previous 48 hours. It excluded patients with a history of thyroid disease. 

Patients underwent an additional nasopharyngeal swab for viral quantification at baseline before were randomly assigned in the ratio 1:1 to a control group (no intervention, n = 12) or an intervention group (n = 12). Intervention consisted of 4 successive mouthwashes and gargles with 25 mL of 1% aqueous PI solution each followed by one 2.5-mL nasal pulverization of the same solution into each nostril. 

The patients were then followed on day 1 and then every 2 days until day 7 for assessing the safety and efficacy of the decolonization. 

Almost all (>95%) of the nasopharyngeal swabs were taken by the same skilled nurse at least 3 hours after the last PI application for quantification of viral RNA using RT-PCR, and viral titer using the dilution limit method on Vero cells and the Spearman-Karber approach with a limit of detection of 102.5 tissue culture infectious dose (TCID50) per mL. Changes in viral load over time were compared between study groups using a linear mixed model for repeated measures. 

"These data call for a larger clinical trial to confirm the benefit of PI in limiting the excretion and resulting human-to-human transmission of SARS-CoV-2, using lower PI concentrations to minimize adverse effects," concluded the authors. 

The study titled, "Povidone Iodine Mouthwash, Gargle, and Nasal Spray to Reduce Nasopharyngeal Viral Load in Patients With COVID-19: A Randomized Clinical Trial," is published in the journal JAMA Otolaryngology - Head & Neck Surgery.

DOI: https://jamanetwork.com/journals/jamaotolaryngology/fullarticle/2775984