Efficacy of Ultraviolet Germicidal Irradiation (UVGI) devices to decrease the incidence of respiratory infections in nursing homes: a cluster randomized crossover trial (RESPROTECT)

Background Ultraviolet germicidal irradiation (UVGI) has long been recognized for its ability to inactivate airborne pathogens under experimental conditions. However, despite strong in vitro evidence, randomized clinical evidence of its real-world effectiveness remains lacking. Nursing homes—where respiratory infections are a major cause of morbidity and mortality—represent a highly relevant setting to evaluate the preventive potential of UVGI. The RESPROTECT trial aims to assess whether continuous UVGI use in communal areas of nursing homes reduces the incidence of severe acute respiratory infections (ARIs) among residents. Methods RESPROTECT is a multicenter, open cohort, quadruple-blind, cluster-randomized, crossover trial. A total of 848 UVGI devices were installed in communal living areas of 12 nursing homes in the Haute-Loire region, France. All devices are switched on, but some contain internal filters that deactivate UV light while remaining indistinguishable from the outside. Centers were randomized 1:1 into two groups: unfiltered UVGI devices active during period 1 (October 2024–April 2025), then filtered (inactive) during period 2 (October 2025–April 2026), or the reverse sequence. The primary outcome is the incidence of severe ARIs. Secondary outcomes include the incidence of ARIs of any grade, all-cause hospitalization or death, adverse events of interest (keratitis and erythema), antibiotic consumption, airborne and surface pathogen loads, and cost-effectiveness. All analyses will follow the intention-to-treat principle and use mixed-effects Poisson regression models with fixed effects for period and random effects for clusters, cluster-periods and individuals. Discussion RESPROTECT is one of the first large-scale blinded randomized trials to evaluate the clinical effectiveness of UVGI in preventing respiratory infections among elderly residents in nursing homes. It will complement recent findings from the PETRA trial ( JAMA Intern Med 2025) and is designed to provide robust data on both clinical outcomes and environmental contamination. If UVGI proves effective, it could represent a practical, low-maintenance, and scalable infection-prevention strategy for high-risk institutional settings. Trial registration : French RCB identifier: RECHMIE-22-0003 - 2024-A00199-38. ClinicalTrials.gov Identifier: NCT06569160 (Registered August 21, 2024).https://clinicaltrials.gov/study/NCT06569160