A range of respiratory illnesses including COVID-19 and influenza could be prevented and treated using a widely available generic antibiotic, the results of a new study revealed.

A team of researchers from Yale tested the effectiveness of antibiotic neomycin in animal models and found that administering the antibiotic neomycin through the nasal passage triggered a robust interferon-stimulated genes (ISG) line of defense against both SARS-CoV-2 and a highly virulent strain of influenza A virus. Also, administering neomycin intranasally significantly reduced the transmission of SARS-CoV-2 through contact in hamsters.

The researchers also found a strong response when they applied over-the-counter Neosporin ointment to the noses of healthy humans. Neosporin contains three antibiotics neomycin, polymyxin B, and bacitracin which is typically used to prevent and treat bacterial skin infections.

The results of the study were published in the journal Proceedings of the National Academy of Sciences.

"This is an exciting finding, that a cheap over-the-counter antibiotic ointment can stimulate the human body to activate an antiviral response," said Akiko Iwasaki, co-senior author of the study from the Yale School of Medicine, in a news release.

"Our work supports both preventative and therapeutic actions of neomycin against viral diseases in animal models, and shows effective blocking of infection and transmission," said Iwasaki.

As of February 2024, there have been over 774.5 million documented cases of SARS-CoV-2 infections worldwide, resulting in 6.9 million deaths. Additionally, influenza viruses are responsible for approximately 5 million severe illness cases and 500,000 deaths annually on a global scale.

The current treatment strategy focuses on stopping the progression of existing respiratory infections and involves the use of antivirals, monoclonal antibodies, and convalescent plasma therapy, which are delivered intravenously or orally.

"A nasal-centered therapy has a much better chance of stopping infections before they can spread to the lower respiratory tract and cause severe diseases," the news release stated.

"This collaborative multi-disciplinary work combined important insights from animal pulmonary infection modeling experiments with human study evaluation of this intranasal approach to stimulate antiviral immunity," former Yale researcher Charles Dela Cruz, who co-led the study, said.

"Our findings suggest that we might be able to optimize this cheap and generic antibiotic to prevent viral diseases and their spread in human populations, especially in global communities with limited resources. This approach, because it is host-directed, should work no matter what the virus is," Iwasaki said.

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