Point of care testing using rapid automated antigen testing for SARS-COV-2 in care homes - an exploratory safety, usability and diagnostic agreement evaluation

Introduction Successful adoption of POCTs (Point-of-Care tests) for COVID-19 in care homes requires the identification of ideal use cases and a full understanding of the contextual and usability factors that affect test results and minimise biosafety risks. This paper presents a scoping-usability and test performance study of a microfluidic immunofluorescence assay for COVID-19 in care homes. Methods A mixed-methods evaluation was conducted in four UK care homes to scope usability and to assess the agreement with qRT-PCR. A dry run with luminescent dye was conducted to explore biosafety issues. Results The agreement analysis was conducted on 227 asymptomatic participants (159 staff and 68 residents) and 14 symptomatic participants (5 staff and 9 residents). Asymptomatic specimens showed 50% (95% CI:1.3%-98.7%) positive agreement and 96% (95% CI: 92.5%-98.1%) negative agreement with overall prevalence and bias-adjusted Kappa (PABAK) of 0.911 (95% CI: 0.857-0.965). Symptomatic specimens showed 83.3% (95% CI: 35.9%-99.6%) positive agreement and 100% (95% CI: 63.1%-100%) negative agreement with overall prevalence and bias-adjusted Kappa (PABAK) of 0.857 (95% CI: 0.549-1). The dry run highlighted four main sources of contamination that led to the modification of the standard operating procedures. Simulation post-modification showed no further evidence of contamination. Conclusion Careful consideration of biosafety issues and contextual factors associated with care home are mandatory for safe use the POCT. Whilst POCT may have some utility for ruling out COVID-19, further diagnostic accuracy evaluations are needed to promote effective adoption.