A recent Australian clinical trial has highlighted the potential of germicidal ultraviolet (UV) light in reducing acute respiratory infections among residents of long-term care facilities. The study, led by Dr Andrew Shoubridge and colleagues, marks one of the first multicentre, pragmatic evaluations of commercially available UV appliances in aged care settings.
Respiratory infections, including influenza, respiratory syncytial virus, and SARS-CoV-2, remain a major threat to older Australians living in residential care, contributing to high rates of hospitalisation and mortality. Traditional infection control measures such as hand hygiene, mask use, and physical distancing reduce, but do not fully prevent, the airborne transmission of viruses.
The trial, known as PETRA (Prevention of SARS-CoV-2 Transmission in Residential Aged Care Using UV Light), was conducted across four long-term care facilities in metropolitan and regional South Australia. Researchers installed germicidal UV (GUV) appliances in communal areas such as dining rooms, corridors, and lobbies, leaving resident rooms and staff-only spaces unaltered. The study ran over 110 weeks, covering two winter respiratory virus seasons, and involved 380 beds and more than 211,000 bed-days.
The trial design included seven cycles where zones within each facility alternated between active UV appliances and inactive periods, allowing researchers to compare infection rates. Across the study, 596 acute respiratory infections (ARIs) were recorded.
While the incidence rate of infections per zone per cycle showed a modest, non-significant decrease, from 4.17 in control zones to 3.81 in UV intervention zones, time-series analysis revealed a statistically significant cumulative effect. The use of UV light was associated with a reduction of 0.32 infections per week, equivalent to a 12.2 per cent decrease over the study period. When memory support units, where infection control is particularly challenging, were excluded, UV light reduced infections by 0.41 per week.
“These findings suggest that while UV light may not dramatically reduce infection rates in the short term, it can meaningfully reduce the total number of infections across longer periods,” the study authors noted. They estimate that an approximately 9 per cent reduction in infections could translate to 92 fewer ARIs per 1,000 residents annually, a significant public health impact considering the vulnerability of this population.
GUV appliances work by sterilising airborne pathogens, including viruses, bacteria, and fungi, as they circulate through a UV-treated air zone. They operate alongside existing infection control measures without disrupting daily care routines or requiring staff and residents to change behaviour.
The study also highlighted practical advantages. Commercially available UV appliances have low running costs and can complement existing HVAC systems for more comprehensive air sterilisation. However, the researchers caution that results may vary depending on appliance type, deployment strategy, and facility layout.
Despite the encouraging outcomes, the trial had limitations. Pandemic-related restrictions prevented some secondary outcomes, such as air and surface sampling, and ARI causes were not always confirmed by laboratory testing. Nevertheless, no adverse events related to the UV appliances were reported.
Dr Geraint Rogers, corresponding author and researcher at the South Australian Health and Medical Research Institute, said, “UV light could be a valuable adjunct to infection control in aged care homes. Even modest reductions in respiratory infections can significantly improve resident health and reduce pressure on hospitals.”
With the ongoing threat of seasonal outbreaks and novel pathogens, strategies that target airborne viral transmission are urgently needed. Germicidal UV light may provide an additional layer of protection for Australia’s most vulnerable older adults.
