HCV Antibody Test for Initial STI Screening
For STI testing, order an HCV antibody test as your initial screening test, using an FDA-approved laboratory-based assay or rapid test. 1
Testing Algorithm
The recommended approach follows a two-step sequence:
Step 1: Initial Screening
- Order an HCV antibody test (anti-HCV) as your first-line screening test 1
- This can be either:
- Laboratory-based enzyme immunoassay (preferred for venipuncture blood)
- OraQuick HCV Rapid Antibody Test (if using fingerstick blood)
Step 2: Reflex Testing Based on Results
If HCV antibody is nonreactive:
- No further testing needed
- Report as negative for HCV
If HCV antibody is reactive:
- Automatically reflex to HCV RNA testing (nucleic acid test/NAT) using the same blood sample 1
- This distinguishes between:
- HCV RNA detected = current active infection (requires treatment)
- HCV RNA not detected = either past resolved infection or false positive antibody
Important Clinical Caveats
Recent Exposure (Within 6 Months)
If you suspect recent HCV exposure, order HCV RNA directly or plan follow-up antibody testing, as antibodies may not yet be detectable in acute infection 1
Immunocompromised Patients
Consider ordering HCV RNA testing directly in immunocompromised individuals, as antibody response may be blunted 1
Why Not Start with HCV RNA?
While HCV RNA is the gold standard for diagnosis 2, the antibody test is the appropriate initial screening test for routine STI testing because it's more cost-effective and identifies both current and past infections. The reflex RNA testing on positive antibodies provides the definitive diagnosis of active infection 1.
Common Pitfall to Avoid
Do not order HCV core antigen as your initial screening test. While HCV antigen assays show promise in research settings 3, 4, the CDC guidelines clearly specify FDA-approved antibody tests for initial screening 1. The antibody-first approach with reflex RNA testing remains the standard of care for STI clinics.