Nasopharyngeal application of povidone iodine (PI) may reduce viral load in adult patients with mild to moderate COVID-19, according to a study published in JAMA Otolaryngology–Head & Neck Surgery.

As PI solutions have been shown to rapidly inactivate SARS-CoV-2 in vitro, this randomized clinical trial aimed to determine whether nasopharyngeal application of PI affects the viral load of patients with mild to moderate COVID-19 symptoms. “We included adult outpatients (≥18 years old) having tested highly positive (cycle threshold ≤20) for SARS-CoV-2 ribonucleic acid (RNA) by reverse transcription-polymerase chain reaction (RT-PCR) in nasopharyngeal swabs within the previous 48 hours,” the authors explained. The study excluded patients who had a history of thyroid disease.

Patients were randomly assigned (1:1) to a control group (n=12) or an intervention group (n=12). The intervention included 4 successive mouthwashes and gargles (each included 25mL of 1% aqueous PI solution), one 2.5mL nasal pulverization in each nostril using the same solution and an intranasal mucosal atomization device connected to a 5mL syringe during sniffing, as well as 1 dab of 10% PI ointment on each nasal mucosa. Applications occurred 4 times daily for 5 days and were self-administered by the patient. Follow-up included assessing both efficacy (viral quantification) as well as safety, and was performed on day 1 followed by every 2 days through day 7.

Patients in the control and intervention groups were well matched, except the patients in the control group were older (median age [IQR], 57 [45-68]) compared to those in the intervention group (median age [IQR], 33 [23-46]). Findings of the study revealed no significant difference in the change of viral RNA quantification between the groups over time.


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However, the analysis did find a significant difference in the mean relative difference in viral titers from baseline to day 1 between the intervention group (75% [95% CI, 43-95]) and control group (32% [95% CI, 10-65]). Safety findings showed that patients who received PI experienced nasal tingling as well as elevations in thyroid stimulating hormone (TSH). These elevations occurred in all patients 5 days after PI exposure and returned to baseline values 7-12 days after. Additionally, TSH elevation was found to exceed the upper normal value in 5 of the patients in the intervention group (42%).

“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,” the authors concluded.

Reference

Guenezan J, Garcia M, Strasters D, et al. Povidone iodine mouthwash, gargle, and nasal spray to reduce nasopharyngeal viral load in patients with COVID19: A randomized clinical trial [published online February 4, 2021]. JAMA Otolaryngol. Head Neck Surg. doi: 10.1001/jamaoto.2020.5490.