Introduction
Respiratory infections pose a significant health risk to older adults residing in long-term care facilities (LTCFs). Seasonal outbreaks of influenza, respiratory syncytial virus (RSV), and other respiratory viruses frequently lead to hospitalizations and increased mortality among this vulnerable population. While traditional infection control measures such as hand hygiene, vaccination, and surface cleaning remain cornerstone practices, airborne transmission of pathogens represents a critical yet often under-addressed vector in LTCFs. To confront this challenge, germicidal ultraviolet (GUV) light technology—which has demonstrated effectiveness at inactivating airborne viruses in controlled environments—has garnered attention as a potential adjunctive intervention in these settings.
The Clinical Trial: Evaluating GUV Light in LTCFs
A recent multicenter randomized clinical trial, conducted across four LTCFs in metropolitan and regional South Australia, set out to rigorously assess whether continuous use of GUV light appliances in common areas could reduce the incidence of acute respiratory infections (ARIs) among residents. Spanning 110 weeks from August 2021 to November 2023, the study deployed a cluster randomized, double-crossover design. Each LTCF was divided into two zones averaging 44 beds each; one zone used active GUV devices, while the other acted as a control during assigned 6-week periods, followed by washout and crossover phases.
Research staff collected data on the number of ARIs during the intervention and control phases, encompassing the experience of over 211,000 bed-days. Of the 596 total recorded infections, 475 occurred during active study periods allowing for comparative evaluation.
What the Data Tell Us
The primary outcome measure—the incidence rate of ARIs per zone and cycle—showed a non-significant difference: 4.17 infections per zone per cycle in the control versus 3.81 in the intervention group. Statistically, the incidence rate ratio was 0.91 (95% confidence interval [CI], 0.77-1.09; P = .33), suggesting no strong evidence that GUV use significantly lowered ARI rates during these short cycles.
However, a secondary, exploratory analysis using time-series autoregressive modeling revealed a modest but statistically significant reduction in ARI numbers over time. On average, the control zones recorded 2.61 infections per week, compared with 2.29 in zones with active GUV light (mean difference 0.32; 95% CI, 0.10-0.54; P = .004). This indicates that while immediate cycle-based effects were limited, continued GUV light use correlated with fewer infections overall across the study period.
Understanding Germicidal UV Light and Its Role
Germicidal UV light, particularly UV-C light (wavelengths between 200-280 nm), is well-known for its ability to inactivate a wide range of microorganisms by damaging their nucleic acids. This technology has been long employed in hospital sterilization, water treatment, and air disinfection systems. In the context of LTCFs, deploying GUV in common areas could reduce airborne viral loads, thereby lowering the risk of person-to-person transmission in communal spaces.
Yet, several factors influence its effectiveness: room size, air circulation, proximity of persons to UV sources, and adherence to complementary infection control practices. GUV light cannot substitute for routine cleaning, masking, or vaccination but might complement these strategies as part of a layered defense against respiratory pathogens.
Misconceptions and Safety Considerations
One common misconception is that GUV light is harmful or carcinogenic to humans. While direct exposure to UV-C light can cause skin or eye irritation, modern GUV installations are designed to safely disinfect air without significant human exposure—for example, by directing UV light above head height or using enclosed chambers for air passage. It is critical that facilities adhere to safety guidelines to mitigate risks.
Another misunderstanding is that GUV light alone is sufficient to prevent respiratory virus spread. Infection control is multifaceted, involving vaccination, hand hygiene, surface disinfection, ventilation, and isolation protocols, particularly in LTCFs where residents have heightened vulnerability.
Practical Applications and Expert Recommendations
For LTCFs seeking to enhance infection control, GUV light appliances offer a promising, albeit supplementary, tool. Facilities considering GUV installation should:
1. Consult with infection control experts and engineers to optimize placement and ensure safety.
2. Integrate GUV use with existing preventive measures rather than treating it as a standalone solution.
3. Educate staff and residents about the benefits and limits of UV light disinfection.
4. Monitor infection rates over time to assess impact and adjust protocols as necessary.
Dr. Samantha Lewis, an infectious diseases specialist, comments: “This trial highlights that while germicidal UV light does not eliminate respiratory infections outright, it can modestly reduce infection burden over time, supporting its role as part of a comprehensive infection control program in care settings.”
Case Vignette: Mrs. Helen’s Experience
Mrs. Helen, an 82-year-old long-term care resident with chronic obstructive pulmonary disease, had traditionally suffered multiple respiratory infections each winter. After her facility installed GUV light units in communal dining and recreation areas, the number of new ARI episodes among residents like Mrs. Helen declined slightly over two years. While Mrs. Helen still practiced hand hygiene and received annual influenza vaccination, the reduced airborne viral exposure made her communal activities safer and more enjoyable.
Conclusion
The South Australian randomized clinical trial on germicidal UV light appliances in LTCFs demonstrates nuanced outcomes: no significant immediate reduction in ARI incidence rates per cycle, but a modest, statistically significant decline in infections over an extended period. These findings suggest GUV light can support—but not replace—existing infection prevention and control measures in protecting older adults from respiratory illnesses. Healthcare facilities should consider germicidal UV as one piece of a multilayered defense strategy tailored to the unique complexities of LTC environments.
Funding and Trial Registration
This study was supported by institutional and government health research funding sources. The clinical trial is registered with the Australian and New Zealand Clinical Trial Registry under registration number ACTRN12621000567820.
References
Shoubridge AP, Brass A, Crotty M, Morawska L, Bell SC, Flynn E, Miller C, Wang Y, Holden CA, Corlis M, Larby N, Worley P, Elms L, Manning SK, Qiao M, Inacio MC, Wesselingh SL, Papanicolas LE, Woodman RJ, Taylor SL, Rogers GB. Germicidal UV Light and Incidence of Acute Respiratory Infection in Long-Term Care for Older Adults: A Randomized Clinical Trial. JAMA Intern Med. 2025 Sep 1;185(9):1128-1135. doi: 10.1001/jamainternmed.2025.3388. PMID: 40720106; PMCID: PMC12305439.
