A New Weapon in The Fight Against Flu

By Jane Farrell

The use of far ultraviolet C (far-UVC) light can kill airborne flu viruses without harming human tissues, researchers say. And the investigators, from the Center for Radiological Research at Columbia University Irving Medical Center (CUIMC), say their findings suggest that such light could be used in hospitals, schools, airports and other public spaces to provide a “powerful check” on seasonal influenza epidemics as well as influenza pandemics.

The study was published online in February 2018 in Scientific Reports.

Scientists have known for decades that broad-spectrum UVC light is highly effective at killing bacteria and viruses by destroying the molecular bonds that hold their DNA together. This kind of UV light is routinely used to decontaminate surgical equipment, but it is dangerous to humans. “Unfortunately, conventional germicidal UV light is…a human health hazard and can lead to skin cancer and cataracts, which prevents its use in public spaces,” said study leader David J. Brenner, PhD, director of the Center for Radiological Research at CUIMC.

According to a news release from Columbia University Medical Center, Brenner and his colleagues hypothesized several that a narrow spectrum of ultraviolet light called far-UVC could kill microbes without damaging healthy tissue and could be used without harm to humans. “Far-UVC light has a very limited range and cannot penetrate through the outer dead-cell layer of human skin or the tear layer in the eye, so it’s not a human health hazard. But because viruses and bacteria are much smaller than human cells, far-UVC light can reach their DNA and kill them,” he said.

In their earlier studies, Brenner’s team demonstrated that far-UVC light was effective at killing MRSA (methicillin-resistant S. aureus) bacteria, a common cause of surgical wound infections, but without harming human or mouse skin.

Influenza virus spreads from person to person mainly through fine liquid droplets, or aerosols, that become airborne when people with flu cough, sneeze, or talk. The new study was designed to test if far-UVC light could efficiently kill aerosolized influenza virus in the air, in a setting similar to a public space. In the study, aerosolized H1N1 virus–a common strain of flu virus–was released into a test chamber and exposed to very low doses of 222 nm far-UVC light. A control group of aerosolized virus was not exposed to the UVC light. The far-UVC light efficiently inactivated the flu viruses.

“If our results are confirmed in other settings, it follows that the use of overhead low-level far-UVC light in public locations would be a safe and efficient method for limiting the transmission and spread of airborne-mediated microbial diseases, such as influenza and tuberculosis,” Brenner said.

At a price of less than $1,000 per lamp–a cost that would be likely to decrease if the lamps were mass produced– far-UVC lights are relatively inexpensive, the news release said. “And unlike flu vaccines,” Brenner said, “far-UVC is likely to be effective against all airborne microbes, even newly emerging strains.”