Could UV light protect against hospital infections?

Healthcare associated infections (HAIs) are a major public health challenge around the world with around seven out of every 100 patients in acute-care hospitals in high-income countries and 15 in low- and middle-income countries acquiring at least one such infection during their hospital stay.

This is according to data from the World Health Organisation that further suggests that on average, 1 in every 10 affected patients die from their HAI.

There are around 165,000 healthcare associated infections (HAIs)¹ in Australian health facilities each year, making them the most common complication affecting patients in hospital.

With the increasing burden of HAIs and antimicrobial resistance, efforts are being made at global, national and regional levels to improve infection prevention and control in hospital and health care facilities.

Limitations of the traditional approach

At this year’s ESCMID Global Congress — an annual congress that brings together experts and specialists working in clinical microbiology and infectious diseases — in Barcelona, Spain (27–30 April), Dr Curtis Donskey from the Louis Stokes Cleveland VA Medical Center in Cleveland, Ohio, USA, will discuss the new ultraviolet light air disinfection technology that could help protect against healthcare infections.

Airborne transmission of diseases such as COVID-19 and tuberculosis in public spaces has highlighted a clear need for improved technologies to limit their spread. Similarly, environmental contamination plays a key role in the spread of healthcare-associated infections, with pathogens such as Methicillin-resistant Staphylococcus aureus (MRSA) and Clostridioides difficile able to persist on surfaces, contributing to the spread of infections.

“Compounding the problem, and a major limitation of traditional cleaning and disinfection strategies, is that disinfected surfaces rapidly become re-contaminated between manual cleaning episodes,” Donskey said.

Ultraviolet light technologies

“Daily cleaning of patient rooms is likely to be inadequate to reduce the burden of infectious pathogens, and manual cleaning of intricate surfaces, equipment and devices makes thorough cleaning difficult. These limitations have led to the development of technologies that can provide continuous decontamination of occupied spaces between episodes of manual cleaning. The Holy Grail is a technology that is effective against surface and airborne pathogens and is automated, safe and reasonably priced.”

One of the most promising candidates is ultraviolet light technology. “It’s been known since the 1940s that ultraviolet light can kill bacteria and inactivate viruses in the air so that they are no longer infectious,” Donskey said.

“Conventional UV light has been used widely in hospitals and prisons, but it can damage the skin and eyes, so it can only be used when a room is empty. Because re-contamination of rooms and surfaces is so quick, the goal has been to continuously decontaminate rooms with people in them.”

Far-ultraviolet light

Far UV-C has a shorter wavelength (222 nm) than conventional germicidal UVC light (254 nm) and cannot penetrate or harm skin, eyes or tissue. Studies have shown that far-UVC light can kill the SARS-CoV-2 virus, other human coronaviruses, influenza and drug-resistant bacteria quickly and efficiently.² And because of the way ultraviolet light kills microbes, viruses and bacteria, they cannot develop resistance as they do with vaccines and drug treatments. Additional tests in real-room environments have found that far UV-C reduced infectious airborne viruses by over 99% — much greater than is generally achieved using typical air filtration and ventilation.³

Beaming this far-UVC into an empty room could decontaminate the air and surfaces in healthcare settings, and as the wavelength of this UV is shorter than conventional UV light, it cannot penetrate or harm our skin, eyes or tissues, according to the researchers.

“Several studies have suggested that far UV-C light at the current regulatory limit may be safe for use around people, but more studies are needed to confirm the safety of these rays in clinical settings and with longer-term follow-up before it is likely that they will be routinely used in occupied healthcare settings,” Donskey cautioned.

“It is also vital that we assess ozone concentrations because far UV-C technologies have the potential to generate modest amounts of ozone.” Based on the information currently available, the US Centers for Disease Control and Prevention has stated that in the near-term, whole-room UV is best viewed as new and emerging technology.

Nevertheless, far UV-C (222 nm) has emerged as a leading continuous decontamination technology with several commercial technologies currently being marketed. A few of the companies marketing far UV-C devices include Ushio (Care222 Filtered Far UV-C Excimer Lamp Module), Sterilray (GermBuster Channel), Lit Thinking (Visium) and Far UV Technologies.

Intermittent delivery

“Some early adopters have begun using these technologies in healthcare settings,” Donskey said.

“For example, a dental office in Ohio installed far UV-C lamps in five patient treatment rooms in 2020 and has operated the technology for thousands of hours with no reports of adverse effects. Partnering with such early adopters could be useful to acquire information on long-term safety of far UV-C.

“One novel approach that could accelerate earlier implementation of far UV-C in clinical settings would be its intermittent rather than continuous delivery. Such an approach would only deliver far UV-C when a room is empty and turns off when people are present. We are currently evaluating this intermittent approach for decontamination of equipment rooms, bathrooms, sinks and patient rooms. We anticipate that hospitals will be more willing to consider use of the technology in clinical areas using this approach while additional safety data is being generated,” he said.

^{1. Mitchell BG, Shaban RZ, MacBeth D, Wood CJ, Russo PL. The burden of healthcare-associated infection in Australian hospitals: a systematic review of the literature. Infection, Disease & Health. 2017 Sep 1;22(3):117-28.}

^{2. Far-UVC light (222 nm) efficiently and safely inactivates airborne human coronaviruses | Scientific Reports (nature.com); Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases | Scientific Reports (nature.com)}

^{3. 222 nm far-UVC light markedly reduces the level of infectious airborne virus in an occupied room | Scientific Reports (nature.com)}

Image credit: iStock.com/Charday Penn