Elderly people who have multiple health problems are at higher risk of illness from viral respiratory infections, such as influenza (the flu) and COVID-19. This is especially true for residents in long-term care because the usual methods of infection control (handwashing, mask-wearing, and distancing) are difficult to enforce due to the memory problems of many residents and the frequently shared common spaces. It can also be difficult to prevent the spread of viral infections within long-term care because many residents are unable to tell their caregivers when they are feeling ill. Also, some elderly people do not show typical symptoms of infection (like fever), instead they may suddenly become confused or weak.

This study will test if a safe form of ultraviolet light (far-UVC) can be effective as an extra method of disinfection (in addition to usual manual cleaning) against airborne and surface viruses that can cause respiratory infections.

Background: Nova Scotia has the highest proportion of seniors in Canada. Investing in high quality and safe long-term care homes is considered an important healthy aging strategy both here and globally. COVID-19 has disproportionately affected the elderly population, especially those with underlying health conditions. Residents of long-term care (LTC) facilities have been particularly vulnerable during this pandemic in Canada and elsewhere. Several approaches have been mandated to mitigate the high transmissibility of the aerosolised SARS-CoV-2 coronavirus. These are guided by three key principles: minimize time of exposure, maximize distance from sources of virus and finally to shield self from virus. As demonstrated in emerging evidence, these can be effective measures provided ability for compliance and human behaviours. Following life-saving public health guidelines has proven monumentally challenging in LTC facilities, due to the high prevalence of dementia and frailty. These severe public health measures and common infection control measures have resulted in other negative consequences for LTC residents, such as an increased feeling of loneliness, depression, and mental illnesses.

A further challenge with this population is early recognition of RVI in LTC residents can be difficult due to non-specific symptoms and the possibility of atypical presentation and lack of fever in the elderly with influenza. In this population, RVI can present as sudden, unexplained deterioration in physical or mental ability or exacerbation of an underlying condition with no other known cause. Additionally, other underlying conditions could impair residents' abilities to verbalize their symptoms. This could result in delays to the implementation of control and treatment strategies.

Rational: Far-UVC is emerging as a safe form of ultraviolet light disinfectant to kill airborne viral transmissions, including SARS CoV-2 virus. Far-UVC light (207-222 nm) in low doses effectively kills pathogens without damaging exposed human tissues. Preliminary data suggests using the regulatory safe level of exposure of lower dose UVC light (far-UVC light) can inactivate >95% of aerosolized H1N1 influenza virus and 90 percent of human coronaviruses in 8 minutes and almost 100 percent in 25 minutes. Despite growing evidence on far-UVC as a safe and viable infection control strategy, there is limited research on the feasibility, acceptability and efficacy of far-UVC in LTC settings.

Main Objective: To determine whether far-UVC light causes a reduction in the incidence of influenza-like illnesses, respiratory infections, and COVID-19 infections, among residents in long term care facilities.

Methodology: This is a cluster randomized control trial designed to identify superiority of the intervention. Residents of three LTC facilities, will be cluster-randomized based on the 'neighbourhoods' they live in (social groups of 18-36) with a 1:1 allocation ratio. Randomization will be stratified by the LTC facility. Neighbourhoods will be randomly assigned to have either 222 nm far-UVC lights installed in common areas (treated) or matching placebo lights without far-UVC capabilities (control). Both groups will still receive standard disinfecting procedures and are subject to Nova Scotia's COVID prevention measures. The far-UVC and fluorescent lights will be placed in high traffic areas (e.g. dining rooms, main corridors). Residents spend approximately 3-4 hours daily in these common areas. The far-UVC lamps will be kept at a wavelength of 222 nm and exposure times that have been demonstrated to be safe for use among elderly populations. The trial period will span over 2-3 flu seasons to allow for sufficient data and sample size to describe the efficacy and sustainability of the far-UVC intervention. To be responsive to key policy and planning needs during post pandemic times, findings will be presented routinely to advisory council members and to relevant stakeholders in the province.

Exclusion Criteria: LTC residents who do not consent to data collection

BIinding in this study involves the use of a placebo arm. The placebo lamps will look exactly like the active far-UVC lamps, but they will produce regular fluorescent light and have no disinfection properties.

The trial will be blinded to everyone involved in the study except for one member of the lead coordinating team who must remain unblinded to provide lamp allocation guidance to the installing electricians. This person will not be involved in data collection or analysis, nor will they have access to participant identifying information, only their deidentified study ID.