Clinical Evaluation of Initial Experiences With the Qualitative Dual Detection of Core Antigen and Antibodies Immunoassay for Hepatitis C Virus Screening Test.

Aim: Hepatitis C virus (HCV) infection remains a global health concern. Although the World Health Organization (WHO) proposed a strategy to eliminate HCV by 2030, Japan faces challenges owing to limited access and insufficient support for high-risk populations. Previously, HCV diagnoses required a two-step process, delaying results and increasing costs. In 2024, Japan introduced the Elecsys HCV Duo immunoassay, which enables the qualitative dual detection of HCV core antigen (HCV Ag) and antibodies against HCV (anti-HCV). This study aimed to evaluate its effectiveness in identifying patients with an active HCV infection.

Methods: A retrospective analysis was conducted on 13,045 patients who underwent HCV screening using the Elecsys HCV Duo immunoassay.

Results: Of these, 244 were positive for HCV Duo. All 14 patients who were positive for HCV Ag and anti-HCV had active infection, as confirmed by HCV-RNA testing. Five HCV Ag-positive but anti-HCV-negative patients were identified as false positives. In contrast, five anti-HCV-positive but HCV Ag-negative patients had active infections with detectable HCV-RNA. A low viral load and possible antibody interference were identified as potential reasons for false-negative HCV Ag results.

Conclusion: The Elecsys HCV Duo immunoassay effectively simplified HCV diagnosis and facilitated early detection and treatment initiation. Although false-negative HCV Ag results occurred, the assay ensured linkage to care for patients with both HCV Ag and anti-HCV positivity. These advancements may contribute to enhanced HCV care and support national elimination efforts.