A study recently published in Proceedings of the National Academy of Sciences suggests that coating the inside of the nose with the over-the-counter antibiotic ointment Neosporin seems to trigger an immune response that may help the body repel respiratory viruses like those that cause COVID-19 and the flu.

Researchers discovered that lab animals whose noses were treated with neomycin, the active component of Neosporin ointment sold over-the-counter, developed a strong immune response against both the COVID-19 virus and a highly virulent strain of influenza.

Dr. Akiko Iwasaki, the study's lead author and a professor of immunobiology at the Yale University School of Medicine, told Salon over the phone that they have decided to see if neomycin can protect animals from COVID and the flu. 

Iwasaki added that neomycin treatment significantly prevented infection and reduced animal disease burden. 

He called the work "encouraging" since it demonstrates how neomycin can produce a localized immune response in animals, which can initiate an antiviral response. He noted that this resulted in the protection that they saw. 

The results are positive for mice and hamsters. However, what about humans?

The researchers applied Neosporin using a cotton swab to the nostrils of healthy volunteers twice a day. Vaseline served as some people's placebo. 

Similar findings were found by the researchers when they assessed their antiviral response. 

He said that when they compared the gene expression in the nose, Neosporin stimulated genes, whereas those who had Vaseline did not. He added that this suggests they could use Neosporin or neomycin in humans to induce this antiviral state they also saw in animals. 

Furthermore, Iwasaki claimed that they know that Neosporin can affect humans in a way comparable to what it did on animals. However, he noted that they have not yet determined if it can stop transmission.