The Effect of Povidone-Iodine Nasal Spray on Nasopharyngeal SARS-CoV-2 Viral Load: A Randomized Control Trial

Abstract

Objectives/hypothesis: To determine the effect of povidone-iodine (PVP-I) nasal sprays on nasopharyngeal (NP) viral load as assessed by cycle threshold (Ct) on quantitative polymerase chain reaction (qPCR) of SARS-CoV-2 in outpatients.

Study design: Three arm, triple blinded, randomized, placebo-controlled clinical trial.

Methods: Participants were randomized within 5 days of testing positive for COVID-19 to receive nasal sprays containing placebo (0.9% saline), 0.5% PVP-I, or 2.0% PVP-I. NP swabs for qPCR analysis were taken at baseline, 1-hour post-PVP-I spray (two sprays/nostril), and 3 days post-PVP-I spray (20 sprays/nostril). Symptom and adverse event questionnaires were completed at baseline, day 3, and day 5. University of Pennsylvania Smell Identification Tests (UPSIT) were completed at baseline and day 30.

Results: Mean Ct values increased over time in all groups, indicating declining viral loads, with no statistically significant difference noted in the rate of change between placebo and PVP-I groups. The 2.0% PVP-I group showed statistically significant improvement in all symptom categories; however, it also reported a high rate of nasal burning. Olfaction via UPSIT showed improvement by at least one category in all groups. There were no hospitalizations or mortalities within 30 days of study enrollment.

Conclusions: Saline and low concentration PVP-I nasal sprays are well tolerated. Similar reductions in SARS-CoV-2 NP viral load were seen over time in all groups. All treatment groups showed improvement in olfaction over 30 days. These data suggest that dilute versions of PVP-I nasal spray are safe for topical use in the nasal cavity, but that PVP-I does not demonstrate virucidal activity in COVID-19 positive outpatients.

Level of evidence: 2 Laryngoscope, 132:2089-2095, 2022.

Keywords: Severe acute respiratory syndrome coronavirus 2; clinical trial; coronavirus disease 2019; cycle threshold; nasal spray; nasopharyngeal swab; povidone-iodine; viral load.