Efficacy of Ultraviolet Germicidal Irradiation (UVGI) Devices to Decrease the Incidence of Respiratory Infections in Nursing Homes : a Cluster Randomized Crossover Trial

"Nursing homes are equipped with UVGI devices in all common living places. UVGI devices can be deactivated by installing an invisible internal filter. The inactivation filters will be installed by a technical team independent of the investigation team. Inactivation will therefore be carried out blind to the care givers and the investigation team. The centers included will be randomized into two arms. In arm A: the UVGI device will be left active during period 1, and filtered/deactivated during period 2. In arm B: the UVGI device will be filtered/deactivated during period 1 and left active during period 2.~The two periods will last 7 months each, and will take place two years in a row on the same dates (October 1 to April 30). They will be separated by a 5-month wash-out period (May 1 to September 30), during which all UVGI equipments will be switched off in both arms."