High-Efficiency Particulate Air Filters to Prevent Winter Respiratory Infections in Care Homes: The AFRI-c Cluster Randomized Clinical Trial

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• Picked for Internal Medicine (top studies of the week, 2 August 2026): Recent Internal Medicine research from a high-quartile journal
• Picked for Infectious Diseases (paper of the day, 28 July 2026).
• Picked for Pulmonary and Respiratory Medicine (paper of the day, 28 July 2026).

Abstract

IMPORTANCE: Portable high-efficiency particulate air (HEPA) filters effectively remove airborne microbes. OBJECTIVE: To investigate whether HEPA filters reduce respiratory infection episodes in care home residents. DESIGN, SETTING, AND PARTICIPANTS: This 2-arm cluster randomized clinical trial included care homes for older adults in England, with or without nursing and dementia care provision, and capacity for 20 or more residents in individual bedrooms. Data were collected between September 2021 and May 2024, with each care home participating for 1 winter. INTERVENTIONS: Up to 5 HEPA filters for communal areas (clean air delivery rate set at 160 m3/h) and up to 16 filters for bedrooms (clean air delivery rate set at 60 m3/h). Both groups continued usual infection prevention and control measures. MAIN OUTCOMES AND MEASURES: The primary outcome was respiratory infection rate per winter per bedroom resident (exposed to bedroom and communal room filters). Secondary outcomes included staff absenteeism. All outcomes were also explored for residents exposed only to communal room filters. RESULTS: During the study period, 91 care homes were randomized, 47 to receive communal room filters, with 569 bedroom residents (median [IQR] age, 87 [81-92] years; 398 [70.0%] female), and 44 without communal room filters, with 589 residents without bedroom filters (median [IQR] age, 88 [82-92] years; 23 [71.8%] female). There was no evidence of a difference in the number of respiratory infections per winter per intervention vs control bedroom residents (0.99 vs 1.04; adjusted incident rate ratio, 0.92; 95% CI, 0.64-1.33; P = .67). There was also no evidence of a difference in the rates of staff absenteeism (adjusted incident rate ratio, 0.80 95% CI, 0.55-1.16; P = .24). Results were similar for the residents exposed only to communal room HEPA filters. CONCLUSIONS AND RELEVANCE: In this cluster randomized clinical trial, there was no difference in resident respiratory infection rates in care homes with HEPA filters in communal areas and bedrooms. Care homes should continue existing recommended prevention measures to control respiratory and other infections. TRIAL REGISTRATION: isrctn.org Identifier: ISRCTN63437172.

Abstract as published, via PubMed.