SARS-CoV-2, the causative agent of COVID-19, can spread through respiratory droplets when an infected person sneezes, coughs or talks. Studies have shown that the virus enters through the nose and mouth into the lungs and both symptomatic and asymptomatic patients have a high viral load in their nasopharynx and oropharynx.

Even though masks reduce the spread of respiratory droplets to an extent, some experts have suggested the use of oral and nasal povidone-iodine (a common antiseptic) to reduce viral load and minimise the risk of transmission of the virus to healthcare workers. The suggestion was inspired by previous studies, which had shown the antiviral effects of the solution on SARS and MERS virus.

Now, a group of researchers claim that the solution indeed kills SARS-CoV-2 and may be used as a nasal wash.

The findings of their study are published in the peer-reviewed journal JAMA otolaryngology–Head & Neck Surgery.

For the study, the researchers exposed the COVID-19 causing virus to various concentrations of povidone-iodine solution for 15 and 30 seconds at a temperature of 22 degrees Celcius. A 70 percent ethanol solution was used as a positive control (which they know works against the virus) and water was used as a negative control (which is known to not work against the virus).

After the exposure time, the solutions were tested for the presence of the virus. It was noted that the povidone-iodine solution (PVP-I) with a concentration as low as 0.5 percent was capable of killing SARS-CoV-2 within 15 seconds. Solutions up to 1.25 percent were suggested to be well tolerated for short-term nasal use as they did not affect the cilia (fine hair) in the nose.

The study suggested that mucus from the nose and other compounds like lipids, extracellular fragments of nucleic acids etc. can act as a sink for iodine and keep it from reaching the infection site. So, the povidone solution concentration has to be kept below the threshold that is harmful to the nose and above the one which is actually effective against the virus.

The authors of the study have said that 15 seconds may be enough to inactivate the virus, using the iodine solution. They further said that if these solutions, in the form of nasal disinfectants, are used for patients before they come in for intranasal procedures, it could help reduce the risk of viral spread through droplets and aerosols.

Researchers further said that medical professionals could instruct patients to use the solution before their appointments, to avoid the spread of the virus in waiting rooms and common areas of the hospitals/clinics.

Researchers also added that this method could reduce the risk of someone getting severe symptoms due to COVID-19, as it can help decrease the viral load that travels to the lungs.

The authors wrote, "povidone-iodine nasal irrigation may be beneficial for the population at large as an adjunct to mask usage as a means of virus mitigation."
However, researchers have cautioned people to NOT TRY THIS AT HOME. The nasal wash is best done under the supervision of a clinician only.