A-244 Performance Comparison of the Alinity i Hepatitis C Core Antigen Assay in Routine Laboratory Testing vs HCV RNA Testing

Abstract Background The elimination of Hepatitis C by 2030 is a goal established by the WHO and other country specific health organizations worldwide. This goal is enabled by the availability of effective treatment regimens. A recent surprise in the US has been the increase in HCV infections during the COVID 19 pandemic, which may be caused by increased needle sharing. HCV Antibody assays have been used to screen for HCV, but confirmation of acute infection is relegated in the current US guidelines to PCR which often takes multiple days and may result in a loss to follow up and treatment, especially in high prevalence populations. HCV Core Antigen is a new immunoassay on the Alinity i system. The aim of the study was to evaluate the precision, linearity, and sensitivity of this research use assay in a US-based population. Methods Alinity i assay HCV Ab is an automated chemiluminescent immunoassay built to measure total antibody to the virus. Similarly, the Alinity i HCV Core Ag is a research use only automated chemiluminescent immunoassay for detection of HCV Core antigen in human plasma and serum. Precision (repeatability, and reproducibility) was determined over 3 days (4–10 replicates/day) using control material consisting of a negative human plasma control, and positive controls made with recombinant core Ag in buffer. Linearity was evaluated by preparing 4 dilutions of a remnant specimen with detectable HCV RNA viral load. Clinical sensitivity was determined using 90 remnant specimens with positive HCV Ab results. Specimens were confirmed positive for Hepatitis C via HCV RNA quantitation using the Aptima HCV Quant Dx transcription-mediated amplification (TMA) assay on the Panther System. Correlation between the HCV Ag assay and TMA was evaluated using specimens submitted for either Hepatitis C infection screening and monitoring of known infection. Results The repeatability of the HCV Ag assay ranged between 3.7% and 11.1% CV depending on the sample S/CO level tested. Dilution recovery averaged 98.2% (range 90.2%–107.3%) and a plot of HCV Ag concentration vs dilution factor showed a correlation coefficient R = 0.998 The Hepatitis C core antigen assay had a correlation coefficient R = 0.92 with the TMA. The HCV assay demonstrated a clinical sensitivity of 96.7% vs TMA. Conclusion The performance characteristics of the Alinity i HCV Core Ag assay highlight an opportunity to speed time to treatment by reflexing on the same instrument from HCV Ab to Ag and