Dilute Povidone-Iodine Nasal Antiseptic Kills SARS-CoV-2 Rapidly in Vitro

By Linda Carroll

September 18, 2020

(Reuters Health) - Within 15 seconds of contact, a povidone-iodine nasal antiseptic at concentrations as low as 0.5% inactivated SARS-CoV-2 in vitro, a new study found.

Working with a low-dose povidone-iodine product provided by Veloce BioPharma, researchers showed that when the antiseptic was applied at 0.5%, 1.25%, and 2.5% concentrations to cell cultures infected with SARS-CoV-2, it completely neutralized the virus, according to the report published in JAMA Otolaryngology-Head & Neck Surgery.

"This study shows that SARS-CoV-2 can be inactivated in as little as 15 seconds," said the study's lead author, Dr. Samantha Frank, a third year resident in the otolaryngology and head and neck surgery program at the University of Connecticut School of Medicine in Farmington. "This is the first step to showing that povidone-iodine in a low dose solution can be used topically within the nasal and oral cavities to inactivate SARS-CoV-2."

"We envision, if tolerated and popularized, that this could be used as a daily or twice daily rinse to decrease virus particles," Dr. Frank said. "A lot of healthcare workers are isolating themselves at the peak of the pandemic because they don't want to asymptomatically spread the virus to their family. If they could neutralize the virus in nasal and oral cavities, they might not be spreading it."

To determine if low doses of povidone-iodine could inactivate SARS-CoV-2, Dr. Frank and her colleagues applied three different concentrations of the antiseptic, as well as ethanol 70% to serve as a positive control and water to serve as a negative control, to test media.

After 15-seconds of contact time, all of the povidone-iodine solutions were effective at reducing greater than 3 log10 of infectious virus dose. The researchers noted no cytotoxic effects during the tests.

The ethanol positive control was effective at reducing greater than 3 log10 of infectious virus dose at 30 seconds, but less effective than povidone-iodine at 15 seconds, reducing only 2.17 log10, Dr. Frank and her colleagues reported. The negative control, water, had no effect on virus load.

The new findings are "pretty promising," said Dr. Anthony DelSignore, an assistant professor in the department of otolaryngology and director of rhinology and endoscopic skull base surgery at Mount Sinai Beth Israel in New York City, who wasn't involved in the study.

"Unfortunately, these are just in vitro studies," Dr. DelSignore said. "To make meaningful results you have to look at this in patient populations. It does contain iodine, which can affect thyroid and other functions. And do we know if it affects the sense of smell or the mucous traveling within the nasal cavity? Until there is in vivo data on that it's hard to come to any conclusions."

While this new research is exciting preclinical work, "it has a long way to go before you can argue that it can be helpful in people," said Dr. Sadiya Khan, an assistant professor of medicine at Northwestern University's Feinberg School of Medicine in Chicago. "I worry about the potential clinical translation too early especially if there is the danger of people going out and buying Betadine or other solutions. It could be dangerous if it's not dilute. At higher concentrations it may hurt the cells."

The treatment really needs to be studied in clinical trials, said Dr. Khan, who also wasn't involved in the study. "Besides the potential discomfort at the initial administration, I'd worry about possible side effects," she added.

SOURCE: https://bit.ly/3klCB9M JAMA Otolaryngology-Head & Neck Surgery, online September 17, 2020.