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A number of POCT devices used for rapid screening of respiratory viral infections including seasonal influenza are now widely available. The viral testing targets in POCT platforms can be single, dual or multiplex; the most common being targeted for Influenza A (and subtypes) Influenza B, SARS-Cov-2, and Respiratory Syncytial Virus (RSV). Platforms tend to be based on nucleic acid amplification technologies (NAAT), which generally have improved sensitivity compared to first generation Antigen based devices.
Studies have shown that their use in well designed and defined settings with appropriate governance arrangements can lead to improved patient triage, better use of isolation rooms during periods of winter pressure, more targeted use of antivirals, reduction in unnecessary antibiotic use and a reduced length of hospital stay.
Two liquid human serum samples are distributed monthly over an extended autumn and winter season with a minimum of 16 samples distributed over the year covering a wide viral load. The samples consist of inactivated virus in a stabilising buffer which may contain Influenza A (either / both H1N1 and H3N2 subtypes), influenza B, RSV, SARS-Cov-2 or no virus. A range of differing viral loads are distributed including samples with single or multiple viruses. The mean Threshold Cycle value (Ct) is also provided for the Real-time PCR (polymerase chain reaction) methods as an estimate of the viral load, however data collected from participants on this parameter is not scored.
The programme assesses the ability of the laboratory / POCT site to correctly identify the virus (es) present in the sample, the sensitivity and specificity of the test at the individual site and the overall performance of the method.
The qualitative scores broadly reflect clinical importance, where the manufacturer quoted sensitivities of the methods / devices, are also considered. A correct identification of the virus (es) is given a score of 0. A sliding scale score of between 3 and 5 is assigned for incorrectly identified results, where 5 represented a gross misclassification of the result.
|POCT Respiratory Virus*|
|Analyte||Approx. Range Covered|
|SARS-CoV-2 Ag (RNA)||Negative / Positive|
|Influenza A||Negative / Positive|
|Influenza B||Negative / Positive|
|RSV||Negative / Positive|