A pilot study of 0.4% povidone-iodine nasal spray to eradicate SARS-CoV-2 in the nasopharynx

Abstract We studied the virucidal efficacy of 0.4% povidone-iodine (PVP-I) nasal spray against SARS-CoV-2 in the patients’ nasopharynx at 3 minutes and 4 hours after PVP-I exposure. We used an open-label, before and after design, single arm pilot study of adult patients with RT-PCR-confirmed COVID-19 within 24 hours. All patients received three puffs of 0.4% PVP-I nasal spray in each nostril. Nasopharyngeal (NP) swabs were collected before the PVP-I spray (baseline, left NP samples), and at 3 minutes (left and right NP samples) and 4 hours post-PVP-I spray (right NP samples). All swabs were coded to blind assessors and transported to diagnostic laboratory and tested by RT-PCR and cultured to measure the viable SARS-CoV-2 within 24 hours after collection. Fourteen patients were enrolled but viable SARS-CoV-2 was cultured from 12 patients (85.7%). The median viral titer at baseline was 3.5 log TCID 50 /mL (IQR 2.8-4.0 log TCID 50 /mL). At 3 minutes post-PVP-I spray via the left nostril, viral titers were reduced in 8 patients (66.7%). At 3 minutes post-PVP-I, the median viral titer was 3.4 log TCID 50 /mL (IQR 1.8-4.4 log TCID 50 /mL) ( P =0.162). At 4 hours post-PVP-I spray via the right nostril, 6 of 11 patients (54.5%) had either the same or minimal change in viral titers. The median viral titer 3 minutes post-PVP-I spray was 2.7 log TCID 50 /mL (IQR 2.0-3.9 log TCID 50 /mL). Four hours post-PVP-I spray the median titer was 2.8 log TCID 50 /mL (IQR 2.2-3.9 log TCID 50 /mL) ( P =0.704). No adverse effects of 0.4% PVP-I nasal spray were detected. We concluded that 0.4% PVP-I nasal spray demonstrated minimal virucidal efficacy at 3 minutes post-exposure. At 4 hours post-exposure, the viral titer was considerably unchanged from baseline in 10 cases. The 0.4% PVP-I nasal spray showed poor virucidal activity and is unlikely to reduce transmission of SARS-CoV-2 in prophylaxis use.