3174 Air filtration to prevent symptomatic winter respiratory infections in care homes: the AFRI-C cluster randomised controlled trial

Abstract Introduction Respiratory tract infections are common in care home residents. Portable high-efficiency particulate air filtration units (HEPAFU) remove airborne microbial particles, but it is unclear if this is sufficient to reduce infections. We set out to investigate the effectiveness of portable HEPAFU to reduce the rate of respiratory infection episodes in care home residents. Method We conducted a two-arm randomised controlled trial, cluster randomised by care home over three winters from 1 September 2021 to 31 May 2024. Care homes were randomised to either HEPAFU in communal rooms and private bedrooms; or usual care. The primary outcome was number of symptomatic winter respiratory infection episodes recorded by care home staff for consented residents. Secondary outcomes included: rates of primary care consultation, antibiotic prescribing, hospitalisations and care home staff absenteeism. Results 91 care homes were randomised: 47 to intervention (569 residents with private room HEPAFU); 44 to usual care (589 control residents). There were 390 and 442 respiratory infection episodes in 95,235 and 102,579 consented intervention and control resident risk-days respectively. There was no difference in the number of respiratory infection episodes per private room resident per winter in intervention vs. control care homes: 0.99vs.1.04, adjusted incident rate ratio (aIRR) 0.92, 95%CI 0.64 to 1.33, p = 0.67. A similar rate was observed in residents exposed to communal room HEPAFUs only. There were no differences seen in the rates of primary care consultation (1.77vs.1.57; aIRR 1.21; 0.91 to 1.62, p = 0.20); antibiotic prescribing (1.55vs.1.47; aIRR 1.14; 0.85 to 1.53, p = 0.36); hospitalisations (0.87vs.0.80; aIRR 1.15; 0.75 to 1.76; p = 0.53) or staff absenteeism (5.04vs.5.76; aIRR 0.80; 0.55 to 1.16; p = 0.24). Conclusions We found no evidence that HEPAFU reduced resident winter respiratory infection episodes. Care homes should continue adhering to nationally recommended infection prevention and control measures and not rely on HEPAFU to reduce respiratory infections.